U.S. patent application number 13/826276 was filed with the patent office on 2014-09-18 for redundantly powered and daisy chained power over ethernet.
This patent application is currently assigned to RAYTHEON BBN TECHNOLOGIES CORP.. The applicant listed for this patent is RAYTHEON BBN TECHNOLOGIES CORP.. Invention is credited to Stephen D. Milligan, Dale Gordon Robertson.
Application Number | 20140265550 13/826276 |
Document ID | / |
Family ID | 51524374 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140265550 |
Kind Code |
A1 |
Milligan; Stephen D. ; et
al. |
September 18, 2014 |
REDUNDANTLY POWERED AND DAISY CHAINED POWER OVER ETHERNET
Abstract
According to one aspect, embodiments of the invention provide a
distributed sensor network comprising an interface unit and a
plurality of sensor strings, each sensor string comprising a
plurality of sensor units coupled in series to a port of the
interface unit, wherein each one of the plurality of sensor units
is configured to be provided both power and network connectivity
via a first cable from one of the interface unit and another sensor
unit within the sensor string and also to provide both power and
network connectivity via a second cable to another sensor unit
within the sensor string, and wherein a first string of the
plurality of sensor strings is configured to be coupled to a second
string of the plurality of sensor strings and wherein at least one
sensor unit within the first string is configured to provide power
to a sensor unit within the second string.
Inventors: |
Milligan; Stephen D.; (Stow,
MA) ; Robertson; Dale Gordon; (Billerica,
MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
RAYTHEON BBN TECHNOLOGIES CORP. |
Cambridge |
MA |
US |
|
|
Assignee: |
RAYTHEON BBN TECHNOLOGIES
CORP.
Cambridge
MA
|
Family ID: |
51524374 |
Appl. No.: |
13/826276 |
Filed: |
March 14, 2013 |
Current U.S.
Class: |
307/1 |
Current CPC
Class: |
H04L 12/10 20130101 |
Class at
Publication: |
307/1 |
International
Class: |
H04L 12/10 20060101
H04L012/10 |
Claims
1. A distributed sensor network, the network comprising: an
interface unit comprising a plurality of ports; and a plurality of
sensor strings, each sensor string comprising a plurality of sensor
units coupled in series to one of the plurality of ports of the
interface unit, wherein each one of the plurality of sensor units
within a sensor string is configured to be provided both power and
network connectivity via a first cable from one of the interface
unit and an adjacent one of the plurality of sensor units within
the sensor string and also to provide both power and network
connectivity via a second cable to an adjacent one of the plurality
of sensor units within the sensor string, and wherein a first
string of the plurality of sensor strings is configured to be
coupled to a second string of the plurality of sensor strings and
wherein at least one of the plurality of sensor units within the
first string is configured to provide power to at least one of the
plurality of sensor units within the second string.
2. The distributed sensor network of claim 1, wherein each one of
the plurality of sensor units within a sensor string comprises: a
first port configured to be coupled to one of the interface unit
and an adjacent one of the plurality of sensor units within the
sensor string via the first cable; and a second port configured to
be coupled to one of the interface unit and an adjacent one of the
plurality of sensor units within the sensor string via the second
cable; wherein the first port and the second port are both
configured to be provided both power and network connectivity from
one of the interface unit and an adjacent one of the plurality of
sensor units within the sensor string via the first cable and to
provide power and network connectivity to an adjacent one of the
plurality of sensor units within the sensor string via the second
cable.
3. The distributed sensor network of claim 2, wherein the second
port of the at least one of the plurality of sensor units within
the first string is configured to be coupled to the second port of
the at least one of the plurality of sensor units within the second
string.
4. The distributed sensor network of claim 2, wherein the first
port is configured to be coupled to one of the interface unit and
an adjacent one of the plurality of sensor units within the sensor
string via Ethernet cabling, and wherein the second port is
configured to be coupled to one of the interface unit and an
adjacent one of the plurality of sensor units within the sensor
string via Ethernet cabling.
5. The distributed sensor network of claim 2, wherein each one of
the plurality of sensor units further comprises: a switch coupled
between the first port and the second port; a power supply coupled
to the switch; a downstream transformer coupled between the first
port and the switch; an upstream transformer coupled between the
second port and the switch; a downstream center tap coupled between
the downstream transformer and the power supply; and an upstream
center tap coupled between the upstream transformer and the power
supply; wherein the downstream center tap is configured to provide
power from the downstream transformer to the power supply, and
wherein the upstream center tap is configured to provide power from
the upstream transformer to the power supply.
6. The distributed sensor network of claim 5, wherein each one of
the plurality of sensor units further comprises: a control
processor coupled to the power supply; and a controller coupled to
the control processor, the downstream center tap and the upstream
center tap, wherein, in response to the downstream center tap
providing power from the downstream transformer to the power supply
and to a determination that an adjacent sensor unit has been
coupled to the second port, the interface unit is configured to
operate the control processor to send a forward power control
signal to the controller to operate the controller to forward power
from the downstream center tap to the upstream center tap, and
wherein, in response to the upstream center tap providing power
from the upstream transformer to the power supply and to a
determination that an adjacent sensor unit has been coupled to the
first port, the interface unit is further configured to operate the
control processor to send a forward power control signal to the
controller to operate the controller to forward power from the
upstream center tap to the downstream center tap.
7. The distributed sensor network of claim 6, wherein the
controller is a "Hot-Swap" controller.
8. The distributed sensor network of claim 6, further comprising an
opto-coupler coupled between the control processor and the
controller to provide isolation.
9. The distributed sensor network of claim 2, wherein the first
string of the plurality of sensor strings is configured to be
coupled to a first port of the plurality of ports of the interface
unit, wherein the second string of the plurality of sensor strings
is configured to be coupled to a second port of the plurality of
ports of the interface unit, and wherein the first string and
second string are configured to form a sensor loop between the
first port and the second port.
10. The distributed sensor network of claim 9, wherein the first
port of a first one of the plurality of sensor units within the
first string of the plurality of sensor strings is coupled to the
first port of the plurality of ports of the interface unit, wherein
the first port of a second one of the plurality of sensor units
within the first string of the plurality of sensor strings is
coupled to the second port of the first one of the plurality of
sensor units within the first string, and wherein the first one of
the plurality of sensor units within the first string is configured
to receive power from the interface unit via the first port and to
provide power to the second one of the plurality of sensor units
within the first string via the second port of the first one of the
plurality of sensor units.
11. A method for providing power to a distributed sensor system,
the distributed sensor system comprising an interface unit having a
plurality of ports, and a plurality of sensor strings, each sensor
string comprising a plurality of sensor units coupled in series to
one of the plurality of ports of the interface unit, the method
comprising: providing power from at least one port of the interface
unit to a first port of a first sensor unit of at least one of the
plurality of sensor strings; powering up the first sensor unit;
forwarding power from a second port of the first sensor unit to a
first port of a second sensor unit of the at least one of the
plurality of sensor strings; powering up the second sensor unit;
monitoring the plurality of sensor strings for a fault condition;
and in response to detecting a fault condition in a first sensor
string of the plurality of sensor strings, providing power from a
second one of the plurality of sensor strings to the first sensor
string to provide power to at least one of the plurality of sensor
units within the first sensor string.
12. The method of claim 11, wherein monitoring the plurality of
sensor strings for a fault condition comprises monitoring the
second port of the first sensor unit for an open-circuit or
short-circuit condition while power is being forwarded to the first
port of the second sensor unit.
13. The method of claim 11, wherein forwarding power from the
second port of the first sensor unit to the first port of a second
sensor unit comprises: providing power from the second port of the
first sensor unit to the first port of a second sensor unit at a
first current level, the first current level sufficient to power
only the second sensor unit; determining if the second sensor unit
has powered up correctly in response to the power provided by the
first sensor unit at the first current level; and in response to a
determination that the second sensor unit has powered up correctly,
providing power from the second port of the first sensor unit to
the first port of a second sensor unit at a second current level,
the second current level greater than the first current level and
sufficient to power a third sensor unit coupled to a second port of
the second sensor unit.
14. The method of claim 13, further comprising: forwarding power
from the second port of the second sensor unit to a first port of
the third sensor unit powering up the second sensor unit; and
powering up the third sensor unit.
15. The method of claim 11, wherein providing power from the second
one of the plurality of sensor strings to the first sensor string
in response to detecting a fault condition in the first sensor
string comprises: identifying a location of the fault condition
within the first sensor string; and providing power from the second
one of the plurality of sensor strings to a group of sensor units
within the first sensor string, the group of sensor units within
the first sensor string coupled between the second sensor string
and the location of the fault condition.
16. The method of claim 15, wherein providing power from the second
one of the plurality of sensor strings to a group of sensor units
coupled between the second sensor string and the location of the
fault condition comprises: forwarding power from a second port of a
third sensor unit within the second one of the plurality of sensor
strings to a second port of a third sensor unit within the first
one of the plurality of sensor strings; powering up the third
sensor unit within the first one of the plurality of sensor
strings; and monitoring the second port of the third sensor unit
within the second one of the plurality of sensor strings for a
fault condition while power is being forwarded to the second port
of the third sensor unit within the first one of the plurality of
sensor strings.
17. The method of claim 16, further comprising: in response to a
determination that a fault condition at the second port of the
third sensor unit within the second one of the plurality of sensor
strings does not exist, forwarding power from a first port of the
third sensor unit within the first one of the plurality of sensor
strings to a second port of a fourth sensor unit within the first
one of the plurality of sensor strings; powering up the fourth
sensor unit within the first one of the plurality of sensor
strings; and monitoring the second port of the third sensor unit
within the first one of the plurality of sensor strings for a fault
condition while power is being forwarded to the second port of the
fourth sensor unit within the first one of the plurality of sensor
strings.
18. The method of claim 11, further comprising providing data from
the at least one port of the interface unit to the first port of
the first sensor unit of at least one of the plurality of sensor
strings; and forwarding data from the second port of the first
sensor unit to the first port of the second sensor unit of the at
least one of the plurality of sensor strings.
19. A Power over Ethernet (PoE) distributed sensor system, the
system comprising: an interface unit comprising a plurality of
ports; a plurality of sensor strings, each sensor string comprising
a plurality of sensor units daisy chained together and coupled to
one of the plurality of ports of the interface unit; and means for
intelligently passing power from sensor unit to sensor unit within
each one of the plurality of sensor strings, powering each one of
the plurality of sensor strings, wherein each one of the plurality
of sensor units within a sensor string is configured to receive
power and data from one of the interface unit and an adjacent one
of the plurality of sensor units within the sensor string and also
to provide power and data to an adjacent one of the plurality of
sensor units within the sensor string.
20. The distributed sensor system of claim 19, further comprising
means for providing redundant power between at least two of the
plurality of sensor strings.
21. A PoE sensor unit; the sensor unit comprising: an Ethernet
switch; and a plurality of ports coupled to the Ethernet switch,
each one of the plurality of ports being configurable to both
receive power from an Ethernet cable coupled to the port and to
provide power to an Ethernet cable coupled to the port, and each
one of the plurality of ports being configurable to both receive
data from an Ethernet cable coupled to the port and to provide data
to an Ethernet cable coupled to the port, wherein the Ethernet
switch is configured to forward data received at one of the
plurality of ports to another one of the plurality of ports, and
wherein the plurality of ports is configured to forward power
received at one of the plurality of ports to another one of the
plurality of ports.
Description
BACKGROUND OF THE DISCLOSURE
[0001] 1. Field of the Invention
[0002] Aspects of the present invention relate generally to
communication systems and more specifically to Power over Ethernet
(PoE) technology.
[0003] 2. Discussion of Related Art
[0004] PoE technology describes a standardized system to pass
electrical power and data to a device on Ethernet cabling. PoE is
commonly used for point to point power of single devices from an
Ethernet switch. For example, a PoE system is typically configured
in a "star topology" where one switch may provide both Ethernet
switching and power supply functionality to one device on each one
of the switches' ports. Standards such as the IEEE 802.3af and
802.3at PoE specifications provide a framework for delivery of
power and data to a device via Ethernet cabling.
SUMMARY
[0005] Aspects in accord with the present invention are directed to
a distributed sensor network, the network comprising an interface
unit comprising a plurality of ports, and a plurality of sensor
strings, each sensor string comprising a plurality of sensor units
coupled in series to one of the plurality of ports of the interface
unit, wherein each one of the plurality of sensor units within a
sensor string is configured to be provided both power and network
connectivity via a first cable from one of the interface unit and
an adjacent one of the plurality of sensor units within the sensor
string and also to provide both power and network connectivity via
a second cable to an adjacent one of the plurality of sensor units
within the sensor string, and wherein a first string of the
plurality of sensor strings is configured to be coupled to a second
string of the plurality of sensor strings and wherein at least one
of the plurality of sensor units within the first string is
configured to provide power to at least one of the plurality of
sensor units within the second string.
[0006] According to one embodiment, each one of the plurality of
sensor units within a sensor string comprises a first port
configured to be coupled to one of the interface unit and an
adjacent one of the plurality of sensor units within the sensor
string via the first cable, and a second port configured to be
coupled to one of the interface unit and an adjacent one of the
plurality of sensor units within the sensor string via the second
cable, wherein the first port and the second port are both
configured to be provided both power and network connectivity from
one of the interface unit and an adjacent one of the plurality of
sensor units within the sensor string via the first cable and to
provide power and network connectivity to an adjacent one of the
plurality of sensor units within the sensor string via the second
cable.
[0007] According to another embodiment, the second port of the at
least one of the plurality of sensor units within the first string
is configured to be coupled to the second port of the at least one
of the plurality of sensor units within the second string. In one
embodiment, the first port is configured to be coupled to one of
the interface unit and an adjacent one of the plurality of sensor
units within the sensor string via Ethernet cabling, and the second
port is configured to be coupled to one of the interface unit and
an adjacent one of the plurality of sensor units within the sensor
string via Ethernet cabling.
[0008] According to one embodiment, each one of the plurality of
sensor units further comprises a switch coupled between the first
port and the second port, a power supply coupled to the switch, a
downstream transformer coupled between the first port and the
switch, an upstream transformer coupled between the second port and
the switch, a downstream center tap coupled between the downstream
transformer and the power supply, and an upstream center tap
coupled between the upstream transformer and the power supply,
wherein the downstream center tap is configured to provide power
from the downstream transformer to the power supply, and wherein
the upstream center tap is configured to provide power from the
upstream transformer to the power supply.
[0009] According to another embodiment, each one of the plurality
of sensor units further comprises a control processor coupled to
the power supply, and a controller coupled to the control
processor, the downstream center tap and the upstream center tap,
wherein, in response to the downstream center tap providing power
from the downstream transformer to the power supply and to a
determination that an adjacent sensor unit has been coupled to the
second port, the interface unit is configured to operate the
control processor to send a forward power control signal to the
controller to operate the controller to forward power from the
downstream center tap to the upstream center tap, and wherein, in
response to the upstream center tap providing power from the
upstream transformer to the power supply and to a determination
that an adjacent sensor unit has been coupled to the first port,
the interface unit is further configured to operate the control
processor to send a forward power control signal to the controller
to operate the controller to forward power from the upstream center
tap to the downstream center tap.
[0010] According to one embodiment, the controller is a "Hot-Swap"
controller. In another embodiment, the distributed sensor network
further comprises an opto-coupler coupled between the control
processor and the controller to provide isolation.
[0011] According to another embodiment, the first string of the
plurality of sensor strings is configured to be coupled to a first
port of the plurality of ports of the interface unit, the second
string of the plurality of sensor strings is configured to be
coupled to a second port of the plurality of ports of the interface
unit, and the first string and second string are configured to form
a sensor loop between the first port and the second port.
[0012] According to one embodiment, the first port of a first one
of the plurality of sensor units within the first string of the
plurality of sensor strings is coupled to the first port of the
plurality of ports of the interface unit, the first port of a
second one of the plurality of sensor units within the first string
of the plurality of sensor strings is coupled to the second port of
the first one of the plurality of sensor units within the first
string, and the first one of the plurality of sensor units within
the first string is configured to receive power from the interface
unit via the first port and to provide power to the second one of
the plurality of sensor units within the first string via the
second port of the first one of the plurality of sensor units.
[0013] Another aspect in accord with the present invention is
directed to a method for providing power to a distributed sensor
system, the distributed sensor system comprising an interface unit
having a plurality of ports, and a plurality of sensor strings,
each sensor string comprising a plurality of sensor units coupled
in series to one of the plurality of ports of the interface unit,
the method comprising providing power from at least one port of the
interface unit to a first port of a first sensor unit of at least
one of the plurality of sensor strings, powering up the first
sensor unit, forwarding power from a second port of the first
sensor unit to a first port of a second sensor unit of the at least
one of the plurality of sensor strings, powering up the second
sensor unit, monitoring the plurality of sensor strings for a fault
condition, and in response to detecting a fault condition in a
first sensor string of the plurality of sensor strings, providing
power from a second one of the plurality of sensor strings to the
first sensor string to provide power to at least one of the
plurality of sensor units within the first sensor string.
[0014] According to one embodiment, monitoring the plurality of
sensor strings for a fault condition comprises monitoring the
second port of the first sensor unit for an open-circuit or
short-circuit condition while power is being forwarded to the first
port of the second sensor unit.
[0015] According to another embodiment, forwarding power from the
second port of the first sensor unit to the first port of a second
sensor unit comprises providing power from the second port of the
first sensor unit to the first port of a second sensor unit at a
first current level, the first current level sufficient to power
only the second sensor unit, determining if the second sensor unit
has powered up correctly in response to the power provided by the
first sensor unit at the first current level, and in response to a
determination that the second sensor unit has powered up correctly,
providing power from the second port of the first sensor unit to
the first port of a second sensor unit at a second current level,
the second current level greater than the first current level and
sufficient to power a third sensor unit coupled to a second port of
the second sensor unit.
[0016] According to one embodiment, the method further comprises
forwarding power from the second port of the second sensor unit to
a first port of the third sensor unit powering up the second sensor
unit, and powering up the third sensor unit.
[0017] According to another embodiment, providing power from the
second one of the plurality of sensor strings to the first sensor
string in response to detecting a fault condition in the first
sensor string comprises identifying a location of the fault
condition within the first sensor string, and providing power from
the second one of the plurality of sensor strings to a group of
sensor units within the first sensor string, the group of sensor
units within the first sensor string coupled between the second
sensor string and the location of the fault condition. In another
embodiment, providing power from the second one of the plurality of
sensor strings to a group of sensor units coupled between the
second sensor string and the location of the fault condition
comprises forwarding power from a second port of a third sensor
unit within the second one of the plurality of sensor strings to a
second port of a third sensor unit within the first one of the
plurality of sensor strings, powering up the third sensor unit
within the first one of the plurality of sensor strings, and
monitoring the second port of the third sensor unit within the
second one of the plurality of sensor strings for a fault condition
while power is being forwarded to the second port of the third
sensor unit within the first one of the plurality of sensor
strings.
[0018] According to one embodiment, the method further comprises in
response to a determination that a fault condition at the second
port of the third sensor unit within the second one of the
plurality of sensor strings does not exist, forwarding power from a
first port of the third sensor unit within the first one of the
plurality of sensor strings to a second port of a fourth sensor
unit within the first one of the plurality of sensor strings,
powering up the fourth sensor unit within the first one of the
plurality of sensor strings, and monitoring the second port of the
third sensor unit within the first one of the plurality of sensor
strings for a fault condition while power is being forwarded to the
second port of the fourth sensor unit within the first one of the
plurality of sensor strings. In another embodiment, the method
further comprises providing data from the at least one port of the
interface unit to the first port of the first sensor unit of at
least one of the plurality of sensor strings, and forwarding data
from the second port of the first sensor unit to the first port of
the second sensor unit of the at least one of the plurality of
sensor strings.
[0019] One aspect in accord with the present invention is directed
to a Power over Ethernet (PoE) distributed sensor system, the
system comprising an interface unit comprising a plurality of
ports, a plurality of sensor strings, each sensor string comprising
a plurality of sensor units daisy chained together and coupled to
one of the plurality of ports of the interface unit, and means for
intelligently passing power from sensor unit to sensor unit within
each one of the plurality of sensor strings, powering each one of
the plurality of sensor strings, wherein each one of the plurality
of sensor units within a sensor string is configured to receive
power and data from one of the interface unit and an adjacent one
of the plurality of sensor units within the sensor string and also
to provide power and data to an adjacent one of the plurality of
sensor units within the sensor string. In one embodiment, the
distributed sensor system further comprises means for providing
redundant power between at least two of the plurality of sensor
strings.
[0020] Another aspect in accord with the present invention is
directed to a distributed sensor network, the network comprising an
interface unit comprising a plurality of ports, and a plurality of
sensor strings, each sensor string comprising a plurality of sensor
units coupled in series to one of the plurality of ports of the
interface unit, wherein each one of the plurality of sensor units
within a sensor string is configured to be provided both power and
network connectivity via a first cable from one of the interface
unit and an adjacent one of the plurality of sensor units within
the sensor string and also to provide both power and network
connectivity via a second cable to an adjacent one of the plurality
of sensor units within the sensor string, and wherein a first
string of the plurality of sensor strings is configured to be
coupled to a second string of the plurality of sensor strings and
wherein at least one of the plurality of sensor units within the
first string is configured to provide power to at least one of the
plurality of sensor units within the second string.
BRIEF DESCRIPTION OF DRAWINGS
[0021] The accompanying drawings are not intended to be drawn to
scale. In the drawings, each identical or nearly identical
component that is illustrated in various FIGs. is represented by a
like numeral. For purposes of clarity, not every component may be
labeled in every drawing. In the drawings:
[0022] FIG. 1 is a block diagram of one embodiment of a daisy
chained PoE sensor system in accordance with one aspect of the
present invention;
[0023] FIG. 2 is a block diagram of a sensor unit in accordance
with one embodiment of the present invention;
[0024] FIG. 3 is a state diagram of an individual sensor unit
within a distributed sensor system, the sensor unit utilizing two
levels of over-current protection, in accordance with one aspect of
the present invention;
[0025] FIG. 4 is a state diagram of the powering of a sensor string
coupled to a sensor interface unit within a sensor system in
accordance with one aspect of the present invention; and
[0026] FIG. 5 is a state diagram of fault recovery logic of a
sensor interface unit within a sensor system in accordance with one
aspect of the present invention.
DETAILED DESCRIPTION
[0027] Embodiments of the invention are not limited to the details
of construction and the arrangement of components set forth in the
following description or illustrated in the drawings. Embodiments
of the invention are capable of being practiced or of being carried
out in various ways. Also, the phraseology and terminology used
herein is for the purpose of description and should not be regarded
as limiting. The use of "including," "comprising," or "having,"
"containing", "involving", and variations thereof herein, is meant
to encompass the items listed thereafter and equivalents thereof as
well as additional items.
[0028] As discussed above, typical PoE systems are configured in a
"star topology" where one "hub" switch provides both Ethernet data
switching and power supply functionality to one device on each one
of the switches' ports. In such a system, a separate Ethernet cable
is utilized to couple each device to its' associated port on the
switch. Therefore, if such a common PoE topology is utilized within
a distributed sensor system (e.g., within a vehicle), each sensor
within the sensor system must be coupled directly to the switch
with an individual Ethernet cable. If any of the sensors within the
sensor system are located a relatively long distance away from the
switch (e.g., at an opposite end of the vehicle than the switch),
relatively long Ethernet cables must be utilized to couple the long
distance sensors to the switch.
[0029] Within certain systems, the length of some of the cables
within a common PoE topology based network may prove problematic
due to certain size, weight, reliability and power restrictions of
the system. For example, where a PoE network is desired to be
utilized within a vehicle and/or within a distributed sensor
system, the added weight and size requirements of a standard "star
topology" PoE system due to the relatively long lengths of some
cables may prove unworkable. Further, it may be desired that the
number and/or overall length of cables within a system be reduced
for a particular application.
[0030] Therefore, embodiments described herein provide a system in
which devices are daisy chained together via Ethernet cables and
power provided from a source through the Ethernet cables is
intelligently passed from device to device, powering the string of
devices. In addition, according to some embodiments, the system
also provides redundant power, redundant network connectivity,
and/or automatic fault detection and isolation for failed devices
and cables.
[0031] FIG. 1 is a block diagram of one embodiment of a daisy
chained PoE sensor system 100 in accordance with one aspect
described herein. The sensor system 100 includes a sensor interface
unit 102, a plurality of sensor units 120-148 and Ethernet cables
154, 155, 157. According to one embodiment, the Ethernet cables
154, 155, 157 are twisted-pair Ethernet cables; however, in other
embodiments the Ethernet cables 154 utilize other Ethernet cable
standards such as coaxial cable. According to another embodiment,
the Ethernet cables 154, 155, 157 may be replaced by another type
of cable capable of carrying both data and power. The sensor
interface unit 102 includes a plurality of ports 104-110. Each
sensor unit 120-148 includes a first port 150 and a second port
152.
[0032] A first sensor unit 120, second sensor unit 122, third
sensor unit 124 and fourth sensor unit 126 are coupled in series to
the first port 104 of the sensor interface unit 102 to form a first
sensor string 112. The first port 150 of the first sensor unit 120
is coupled via an Ethernet cable 154 to the first port 104 of the
sensor interface unit 102. The second port 152 of the first sensor
unit 120 is coupled via an Ethernet cable 154 to the first port 150
of the second sensor unit 122. The second port 152 of the second
sensor unit 122 is coupled via an Ethernet cable 154 to the first
port 150 of the third sensor unit 124. The second port 152 of the
third sensor unit 124 is coupled via an Ethernet cable 154 to the
first port 150 of the fourth sensor unit 126.
[0033] A fifth sensor unit 128, sixth sensor unit 130, seventh
sensor unit 132 and eight sensor unit 134 are coupled in series to
the second port 106 of the sensor interface unit 102 to form a
second sensor string 114. The first port 150 of the fifth sensor
unit 128 is coupled via an Ethernet cable 154 to the second port
106 of the sensor interface unit 102. The second port 152 of the
fifth sensor unit 128 is coupled via an Ethernet cable 154 to the
first port 150 of the sixth sensor unit 130. The second port 152 of
the sixth sensor unit 130 is coupled via an Ethernet cable 154 to
the first port 150 of the seventh sensor unit 132. The second port
152 of the seventh sensor unit 132 is coupled via an Ethernet cable
154 to the first port 150 of the eighth sensor unit 134.
[0034] A ninth sensor unit 136, tenth sensor unit 138, eleventh
sensor unit 140 and twelfth sensor unit 142 are coupled in series
to the third port 108 of the sensor interface unit 102 to form a
third sensor string 116. The first port 150 of the ninth sensor
unit 136 is coupled via an Ethernet cable 154 to the third port 108
of the sensor interface unit 102. The second port 152 of the ninth
sensor unit 136 is coupled via an Ethernet cable 154 to the first
port 150 of the tenth sensor unit 138. The second port 152 of the
tenth sensor unit 138 is coupled via an Ethernet cable 154 to the
first port 150 of the eleventh sensor unit 140. The second port 152
of the eleventh sensor unit 140 is coupled via an Ethernet cable
154 to the first port 150 of the twelfth sensor unit 142.
[0035] A thirteenth sensor unit 142, fourteenth sensor unit 144,
fifteenth sensor unit 146 and sixteenth sensor unit 148 are coupled
in series to the fourth port 110 of the sensor interface unit 102
to form a fourth sensor string 118. The first port 150 of the
thirteenth sensor unit 142 is coupled via an Ethernet cable 154 to
the fourth port 110 of the sensor interface unit 102. The second
port 152 of the thirteenth sensor unit 142 is coupled via an
Ethernet cable 154 to the first port 150 of the fourteenth sensor
unit 144. The second port 152 of the fourteenth sensor unit 144 is
coupled via an Ethernet cable 154 to the first port 150 of the
fifteenth sensor unit 146. The second port 152 of the fifteenth
sensor unit 140 is coupled via an Ethernet cable 154 to the first
port 150 of the sixteenth sensor unit 142.
[0036] The first sensor string 112 and the second sensor string 114
are coupled together via an Ethernet cable 155 to form a first
sensor loop 156 between the first port 104 and the second port 106
of the sensor interface unit 102. The Ethernet cable 155 is coupled
between the output 152 of the fourth sensor unit 126 and the output
152 of the eight sensor unit 134. The third sensor string 116 and
the fourth sensor string 118 are coupled together via an Ethernet
cable 157 to form a second sensor loop 158 between the third port
108 and the fourth port 110 of the sensor interface unit 102. The
Ethernet cable 157 is coupled between the output 152 of the twelfth
sensor unit 142 and the output 152 of the sixteenth sensor unit
148.
[0037] As described herein, the sensor interface unit 102 includes
four ports 104-110; however, in other embodiments, the sensor
interface unit may be configured with any number of ports. As also
described herein, the sensor system 100 includes four sensor
strings 112-118; however, in other embodiments, the sensor system
100 may be configured with any number of sensor strings. Also, as
described herein, each sensor string includes four sensor units
120-148; however, in other embodiments, each sensor string may
include any appropriate number of sensor units capable of being
powered by the sensor interface unit 102.
[0038] In the sensor system 100, each sensor unit 120-148 is
provided network connectivity (i.e. transmits and receives data
to/from other devices in the sensor system 100) and is sourced over
the Ethernet cables 154. According to one embodiment, each sensor
120-148 is provided network connectivity at each one of its ports
150, 152, is capable of receiving power at either one of its ports
150, 152, and is capable of providing power to either one of its
ports 150, 152.
[0039] For example, according to one embodiment, one port of each
sensor is designated an "upstream" port and the other port is
designated a "downstream" port. In one embodiment, the "downstream"
port of a sensor unit 120-148 is configured to receive power from a
"downstream" source (e.g., from another sensor unit 120-148 or the
sensor interface unit 102), the "upstream" port of the sensor unit
120-148 is configured to provide power to an "upstream" device
(e.g., another sensor unit 120-148), and both the "upstream" and
"downstream" ports 150, 152 are also configured to provide network
connectivity to the sensor unit 120-148 (i.e., to allow the sensor
unit 120-148 to communicate with other "upstream" or "downstream"
devices).
[0040] In another embodiment, the "downstream" port of a sensor
unit 120-148 is configured to provide power to a "downstream"
device (e.g., another sensor unit 120-148), the "upstream" port of
the sensor unit 120-148 is configured to receive power from an
"upstream" source (e.g., another sensor unit 120-148), and both the
"upstream" and "downstream" ports 150, 152 are also configured to
provide network connectivity to the sensor unit 120-148 (i.e., to
allow the sensor unit 120-148 to communicate with other "upstream"
or "downstream" devices).
[0041] By sourcing each sensor unit 120-148 on either one of its
ports 150, 152 in a daisy chained configuration as described, the
weight of the sensor system 100 may be reduced. For example, in
such a daisy chained configuration, even if a sensor unit 120-148
is a relatively long distance away from the central interface unit
102, the long distance sensor 120-148 must only be coupled to
another nearby sensor, rather than directly to the central
interface unit 102 (as typically done in a conventional PoE "star
topology"). Accordingly, the relatively long (and relatively heavy)
wires typically utilized in conventional PoE "star topology"
network to couple a long distance sensor to a central switch are
not required and may be replaced with relatively short (and
relatively light) sensor to sensor cables, thus reducing the
overall length of cable required for a particular
implementation.
[0042] In addition, by configuring the sensor strings 112-118 in
loops, redundant network connections and power delivery paths are
also provided. For example, as shown in FIG. 1, the first sensor
loop 156 provides redundant network connectivity and power delivery
to sensor units one 120 to eight 134 and the second sensor loop 158
provides redundant network connectivity and power delivery to
sensor units nine 136 through sixteen 148. In this way, network
connectivity and power may be provided to each sensor unit 120-148
from either direction (i.e. from "upstream" or "downstream") in
response to a detected fault in one of the loops 156, 158.
[0043] Each sensor unit 120-148 and the sensor interface unit 102
individually manages the connections to its neighboring device. For
example, upon powering up, the sensor interface unit 102 enables
power onto its ports 104-110. Power from each one of the ports
104-110 is provided to a first port 150 of a connected sensor unit
(e.g., first, fifth, ninth and thirteenth sensor units 120, 128,
136, 142, respectively) to power up each sensor unit. Upon
completion of their power on sequences, the first, fifth, ninth and
thirteenth sensor units 120, 128, 136, 142 enable their power
forwarding circuitry, thereby powering their upstream neighbors
(e.g., the second, sixth, tenth and fourteenth sensor units 122,
130, 138, 144, respectively). This sequence may continue until all
sensor units in each string are powered.
[0044] According to one embodiment, the power forwarding circuit
design of each sensor unit 120-148 may utilize two levels of
over-current protection. For example, when initially providing
power to a neighboring sensor unit, a source sensor unit (e.g.,
first sensor unit 120) may set a "low" current limit which is
sufficient to power the neighboring sensor unit (e.g., second
sensor unit 122) but insufficient to immediately power sensor units
further "upstream" or "downstream". Once the neighbor (e.g., the
second sensor unit 122) is powered up, the source sensor (e.g., the
first sensor unit 120) may then raise the over-current limit to a
"high" current limit so as to allow its neighbor (e.g., the second
sensor unit 122) to power other sensor units further "upstream" or
"downstream" (e.g., third sensor unit 124). The two-level current
limit is designed so that a short circuit or over-current fault
condition on one link or sensor unit will be detected by the
individual source sensor unit while attempting to power the faulty
link or sensor unit in the "low" current limit state and the fault
will not be propagated down the sensor string. In addition, by
utilizing two levels of over-current protection, the system 100 can
also determine the specific location in the system 100 where the
fault exists.
[0045] FIG. 2 illustrates a block diagram of a sensor unit 120 in
accordance with one aspect described herein. The sensor unit 120
includes an Ethernet switch 202, the first port 150 (i.e. a
"downstream" port), the second port 152 (i.e. an "upstream port"),
a sensor control processor 204, an opto-coupler 206, a downstream
transformer 208, an upstream transformer 212, a downstream PoE
center tap 216, a downstream PoE return center tap 218, an upstream
PoE center tap 220, an upstream PoE return center tap 222,
downstream positive reception lines 224, downstream negative
reception lines 226, downstream positive transmission lines 228,
downstream negative transmission lines 230, upstream positive
reception lines 232, upstream negative reception lines 234,
upstream positive transmission lines 236, upstream negative
transmission lines 238, a power supply 240, a downstream PoE diode
242, an upstream PoE diode 244, a "Hot-Swap" controller 246, a
downstream "Hot-Swap" diode 248, and an upstream "Hot-Swap" diode
250.
[0046] In one embodiment, the Ethernet switch 202 is coupled to the
"downstream" port 150 with reception lines 224, 226 and
transmission lines 228, 230 via the downstream transformer 208. The
Ethernet switch 202 is coupled to the "upstream" port 150 with
reception lines 232, 234 and transmission liens 236, 238 via the
upstream transformer 212. The Ethernet switch 202 is also coupled
to the power supply 240 via a supply line (Vcc) 210. The Ethernet
switch 202 is also coupled to the sensor control processor 204 via
an interface line 260. According to one embodiment, the interface
line 260 is a Media Independent Interface (MII) or a Reduced Media
Independent Interface (RMII); however, in other embodiments, the
interface line 260 may be configured differently.
[0047] The downstream PoE center tap 216 is coupled to the
downstream transformer 208 between the downstream reception lines
224, 226. The downstream PoE return center tap 218 is coupled to
the downstream transformer 208 between the downstream transmission
lines 228, 230. The upstream PoE center tap 220 is coupled to the
upstream transformer 212 between the upstream reception lines 232,
234. The upstream PoE return center tap 222 is coupled to upstream
transformer 212 between the upstream transmission lines 236, 238.
Both the downstream PoE return center tap 208 and the upstream PoE
return center tap 222 are also coupled to ground 214. The
downstream PoE center tap 216 is also coupled to a sensor power
line 262 via the downstream PoE diode 242. The upstream PoE center
tap 220 is also coupled to the sensor power line 262 via the
upstream PoE diode 244. According to one embodiment, the downstream
PoE diode 242 and the upstream PoE diode 244 are ideal diode
circuits; however, in other embodiments, the diodes may be
configured differently. The sensor power line 262 is coupled to the
power supply 240 and to the "Hot-Swap" controller 246.
[0048] The sensor control processor 204 is coupled to the power
supply 240 via the supply line (Vcc) 210. The sensor control
processor 204 is also coupled to the opto-coupler 206 via a power
forward control line 264. The power forward control line 264 is
coupled from the opto-coupler 206 to the "Hot-Swap" controller 246.
The "Hot-Swap" controller 246 is coupled to the downstream PoE
center tap 216 via the downstream "Hot-Swap" diode 248 and to the
upstream PoE center tap 220 via the upstream "Hot-Swap" diode 250.
According to one embodiment, the downstream "Hot-Swap" diode 248
and the upstream "Hot-Swap" diode 250 are ideal diode circuits;
however in other embodiments, the diodes may be configured
differently.
[0049] According to one embodiment, the sensor unit 120 is
configured to be located in a sensor loop of a daisy chained PoE
sensor system (e.g., in one of the sensor loops 156, 158 of the
daisy chained PoE sensor system 100 described above in relation to
FIG. 1). In such a system 100, a device connected to the sensor
unit 120 at either its "downstream" port 150 or "upstream" port 152
may be a similar sensor (e.g., sensor unit 122) or the sensor
interface unit 102. As described above, the sensor unit 120 may
receive power and be provided network connectivity at either its
"downstream" port 150 or its "upstream" port 152, forward power to
the other port, and provide network connectivity to the other
port.
[0050] If the sensor 120 is powered by the device (e.g., a similar
sensor or the sensor interface unit 102) coupled to its
"downstream" port 150, then sensor 120 receives power from the
"downstream" device as a common mode DC voltage between the
downstream reception line pair 224, 226 and the downstream
transmission line pair 228, 230. The common-mode DC voltage between
the downstream reception line pair 224, 226 and the downstream
transmission line pair 228, 230 is received by the downstream PoE
center tap 216 and the downstream PoE return center tap 218 and
provided to the sensor power line 262 via the downstream PoE diode
242. The power provided to the sensor power line 262 is provided to
the power supply 240 which generates supply voltage Vcc. Supply
voltage Vcc is provided to different elements of the sensor 120
such as the Ethernet switch 202 and the sensor control processor
204.
[0051] Upon being adequately powered, the sensor 120 may then
forward power on to a device (e.g., a similar sensor circuit)
coupled to its "upstream" port 152. When power forwarding is
desired, the sensor control processor 204 sends a power forward
control signal to the "Hot-Swap" Controller 246 via the power
forward control line 264 and the opto-coupler 206. The opto-coupler
206 may provide isolation between the sensor control processor 204
and the "Hot-Swap" controller 246. In response to the power forward
control signal on the power forward control line 264, the
"Hot-Swap" controller 246 provides power from the sensor power line
262 to the upstream PoE center tap 220 via the upstream "Hot-Swap"
diode 250. Power provided by the sensor power line 262 to the
upstream PoE center tap 220 is applied as a common-mode voltage
between the upstream reception line pair 232, 234 and the upstream
transmission line pair 236, 238. The device coupled to the
"upstream" port 152 may then receive power from the sensor unit 120
on either one if its ports, power itself up, and forward power on
as described above with regards to sensor unit 120.
[0052] In the configuration described above, the power in the
sensor loop flows from the sensor units 120 "downstream" port 150,
coupled to a "downstream" power source (e.g., a similar sensor or
sensor interface unit 102), to the "upstream" port, coupled to an
"upstream" device (e.g., a similar sensor). However, the reverse of
this configuration is also possible where the sensor unit 120 is
powered by a neighboring device (e.g., a similar sensor or sensor
interface unit 102) coupled to the "upstream" port and power is
forwarded to a neighboring device (e.g. a similar sensor) coupled
to the "downstream" port.
[0053] For example, if the sensor 120 is powered by the device
(e.g., a similar sensor or the sensor interface unit 102) coupled
to its "upstream" port 152, the sensor 120 receives power from the
"upstream" device as a common-mode DC voltage between the upstream
reception line pair 232, 234 and the upstream transmission line
pair 236, 238. The common-mode DC voltage between the upstream
reception line pair 232, 234 and the upstream transmission line
pair 236, 238 is received by the upstream PoE center tap 220 and
the upstream PoE return center tap 222 and provided to the sensor
power line 262 via the upstream PoE diode 244. The power provided
to the sensor power line 262 is provided to the power supply 240
which generates supply voltage Vcc. Supply voltage Vcc is provided
to different elements of the sensor 120 such as the Ethernet switch
202 and the sensor control processor 204.
[0054] Upon being adequately powered, the sensor 120 may then
forward power on to a device (e.g., a similar sensor circuit)
coupled to its "downstream" port 150. When power forwarding is
desired, the sensor control processor 204 sends a power forward
control signal to the "Hot-Swap" Controller 246 via the power
forward control line 264 and the opto-coupler 206. The opto-coupler
206 may provide isolation between the sensor control processor 204
and the "Hot-Swap" controller 246. In response to the power forward
control signal on the power forward control line 264, the
"Hot-Swap" controller 246 provides power from the sensor power line
262 to the downstream PoE center tap 216 via the downstream
"Hot-Swap" diode 248. Power provided by the sensor power line 262
to the downstream PoE center tap 216 is applied as a common-mode
voltage between the downstream reception line pair 224, 226 and the
downstream transmission line pair 228, 230. The device coupled to
the "downstream" port 150 may then receive power from the sensor
unit 120 on either one if its ports, power itself up, and forward
power on as described above with regards to sensor unit 120.
[0055] According to one embodiment, the "Hot-Swap" controller 246
allows a neighboring device to safely connect to the port 150, 152
of an already powered sensor unit. For example, in one embodiment
where a neighboring device is suddenly coupled to the port of an
already powered sensor unit 120, the "Hot Swap" controller 246 of
the powered sensor unit 120 applies the power from the sensor power
line 262 to the port (i.e. to the neighboring device) in a
controlled manner, allowing the neighboring device to be safely
inserted (or removed) from the live sensor unit 120 and sensor
loop. The device may also provide undervoltage, overvoltage, and/or
overcurrent protection. According to one embodiment, the "Hot-Swap"
controller 246 is an LT4256-3 Positive High Voltage Hot Swap
Controller manufactured by Linear Technology of Milpitas, Calif.;
however, in other embodiments another type of "Hot-Swap" controller
may be utilized. According to another embodiment, the "Hot-Swap"
controller 246 may be replaced by a controller that is not a
"Hot-Swap" controller but that is capable of controlling power
provided to the downstream PoE center tap 216 and upstream PoE
center tap 220 from the sensor power line 262.
[0056] According to one embodiment, each sensor unit 120 not only
provides power to a "downstream" or "upstream" device, but also
performs data forwarding operations from one port to another. For
example, in one embodiment, the Ethernet switch 202 may receive
data from a "downstream" port 150 (coupled to a "downstream" device
such as the sensor interface unit 102 or another similar sensor
unit 120) via reception lines 224, 226 and forward the data to an
"upstream" port 152 (coupled to an "upstream" device such as a
similar sensor unit 120) via transmission lines 236, 238. In
another embodiment, the Ethernet switch 202 may receive data from
an "upstream" port 152 (coupled to an "upstream" device such as
another similar sensor unit 120) via reception lines 232, 234 and
forward the data to a "downstream" port 150 (coupled to a
"downstream" device such as the sensor interface unit 102 or a
similar sensor unit 120) via transmission lines 228, 230.
Accordingly, as each sensor unit 120 may be placed as an
intermediate sensor within a sensor string (i.e., between other
devices in the string) and each sensor unit 120 includes a
data-forwarding Ethernet switch 202, an overall length of a string
of sensors may exceed the conventional permitted length limits of
an Ethernet Cable.
[0057] In addition, according to one embodiment, the Ethernet
switch 202 receives information from the control processor 204 via
the interface line 260 and forwards the information to at least one
of the "upstream" and "downstream" ports 150, 152. For example,
according to one embodiment, the Ethernet switch 202 receives
sensor data from the control processor 205 via the interface line
260 and forwards the sensor data to at least one of the "upstream"
and "downstream" ports 150, 152.
[0058] As discussed above, according one embodiment, the sensor
unit 120 may utilize two levels of over-current protection. For
example, FIG. 3 illustrates an example state diagram 300 of the
individual sensor unit 120 within the distributed sensor system
100, the sensor unit 120 utilizing two levels of over-current
protection.
[0059] At state 302, the sensor unit 120 is in a powered state
after receiving power provided to one of the sensor unit's ports
150, 152 from a neighboring device (e.g., a similar sensor or
sensor interface unit 102). At state 304, a determination is made
by the sensor control processor 204 whether the processor 204 has
received a signal from the sensor interface unit 102 indicating
that the sensor unit 120 should enable power forwarding at a
desired port. In response to a determination that the sensor unit
120 has not yet received a signal from the sensor interface unit
102 to begin power forwarding the sensor unit 120 remains in state
302.
[0060] In response to a determination by the sensor control
processor 204 that a signal from the sensor interface unit 102 has
been received indicating that the sensor unit 120 should forward
power to a neighboring device (e.g., a similar sensor unit) via a
desired port, at state 306 the sensor control processor 204
provides a power forward control signal to the "Hot-Swap"
controller 246 via the power forward control line 264, enabling the
"Hot-Swap" controller 246 to provide power to the desired port
(i.e. to the neighboring device). Also in state 306, a "low"
current limit is set for the power being provided to the desired
port. As described above, the "low" current limit is chosen such
that only a single sensor unit can be powered.
[0061] At state 308, a determination is made whether the voltage at
the desired port is acceptable at the "low" current limit (i.e. a
short-circuit condition is not present). In response to a
determination that the voltage at the desired port is unacceptable,
at state 312 the sensor control processor 204 sends a control
signal to the "Hot-Swap" controller 246, controlling the controller
246 to stop providing power to the desired port. (e.g., disabling
power forwarding of the sensor unit 120). Once power forwarding is
disabled in the sensor unit 120, the sensor unit 120 returns to
state 304 and the sensor control processor 204 awaits a signal from
the sensor interface unit 102 to begin power forwarding.
[0062] In response to a determination that the voltage at the
desired port is acceptable, at state 310 the sensor control
processor 204 determines if there is an open-circuit condition
present at the desired port. According to one embodiment, an
open-circuit present condition would indicate that either the cable
154 adjoining the two sensors has failed, or that the neighboring
sensor has failed in a way that is causing no power to be consumed
on the desired port. In response to a determination that there is
an open circuit at the desired port, the sensor unit transitions to
state 312 and disables power forwarding of the sensor unit 120. In
response to a determination that there is not an open circuit at
the desired port, at state 314 the sensor control processor 204
sets a "high" current limit for the power being provided to the
desired port. As discussed above, the "high" current limit is
chosen such that it is sufficient to source current to the maximum
number of sensor units in the sensor loop.
[0063] At state 316, the power forwarding status of the sensor unit
120 is labeled "Good" (i.e. the short-circuit and open-circuit
tests have passed) and at state 318, the continued status of the
desired port is monitored by the sensor control processor 204. In
response to a determination that the status of the desired port is
still "Good", the sensor control processor 204 continues to monitor
the status of the desired port. In response to a determination that
the status of the desired port is no longer "Good" (e.g., as a
result of a fault occurring in the sensor unit 120, in the link to
the neighboring device or in the neighboring device itself), the
sensor unit transitions to state 312 and disables power forwarding
of the sensor unit 120 to the desired port. The power forwarding
process described above with regards to FIG. 3 may be repeated for
each sensor unit within a sensor loop until all sensors within the
loop are powered.
[0064] In response to a failed condition (e.g., at state 312 of
FIG. 3), the daisy chained PoE sensor system 100 may also provide
redundant power, redundant network connectivity, and/or automatic
fault detection and isolation. FIG. 4 illustrates a state diagram
400 of the powering of the first sensor string 112 coupled to the
sensor interface unit 102 within the sensor system 100.
[0065] At state 402, the sensor interface unit 102 enables power at
the first port 104 coupled to the first sensor unit 120. At state
404, a determination is made whether the power at the first port
104 is "Good" (i.e. the power at the first port passes the
short-circuit and open-circuit tests described above with regards
to FIG. 3). In response to a determination that the power at the
first port is not "Good", at state 406 the sensor interface unit
102 identifies that there is either a fault in the cable connecting
the sensor interface unit 102 to the first sensor 120 or there is a
fault in the first sensor 120 itself. As a result, the sensor
interface unit 102 initiates fault recovery logic at state 442.
Fault recovery logic, at state 442, is discussed in greater detail
below with regards to FIG. 5.
[0066] In response to a determination that the power at the first
port is "Good", at state 408 the sensor interface unit 102
determines if the first sensor unit 120 has powered up
appropriately. If powered up appropriately, the sensor interface
unit 102 receives a signal from the sensor control processor 204 of
the first sensor unit 120 indicating as such. In response to a
determination that the first sensor unit 120 has not powered up
appropriately, at state 410 the sensor interface unit 102
identifies that the first sensor unit 120 itself has failed. As a
result, the sensor interface unit 102 initiates fault recovery
logic at state 442.
[0067] In response to a determination that the first sensor unit
120 has powered up appropriately with power from the first port
104, at state 412 the sensor interface unit 102 sends a control
signal to the first sensor unit 120, enabling power forwarding in
the first sensor unit 102. In response to the power forwarding
command from the sensor interface unit 102, the first sensor unit
120 provides power to the second sensor unit 122 as similarly
described above with regards to FIG. 3. At state 414, a
determination is made whether the power forwarding status of the
first sensor unit 120 is labeled "Good". As described above with
regards to FIG. 3, the power forwarding status of the first sensor
unit 120 is labeled "Good" when the power at the desired port 152
of the first sensor unit 120 passes short-circuit and open-circuit
tests while providing power to the port 150 of the second sensor
unit 122.
[0068] In response to a determination that the power forwarding
status of the first sensor unit 120 is not labeled "Good", at state
416 the sensor interface unit 102 identifies that there is a fault
in either the cable 154 between the ports of the first sensor unit
120 and the second sensor unit 122 or in the second sensor unit 122
itself. As a result, the sensor interface unit 102 initiates fault
recovery logic at state 442.
[0069] In response to a determination that the power forwarding
status of the first sensor unit 120 is labeled "Good", at state 418
the sensor interface unit 102 determines if the second sensor unit
122 has powered up appropriately. If powered up appropriately, the
sensor interface unit 102 receives a signal from the sensor control
processor 204 of the second sensor unit 122 indicating as such. In
response to a determination that the second sensor unit 122 has not
powered up appropriately, at state 420 the sensor interface unit
102 identifies that the second sensor unit 122 itself has failed.
As a result, the sensor interface unit 102 initiates fault recovery
logic at state 442.
[0070] In response to a determination that the second sensor unit
120 has powered up appropriately with power from the first sensor
unit 120, at state 422 the sensor interface unit 102 sends a
control signal to the second sensor unit 122, enabling power
forwarding in the second sensor unit 122. In response to the power
forwarding command from the sensor interface unit 102, the second
sensor unit 122 provides power to the third sensor unit 124 as
similarly described above with regards to FIG. 3. At state 424, a
determination is made whether the power forwarding status of the
second sensor unit 122 is labeled "Good". As described above with
regards to FIG. 3, the power forwarding status of the second sensor
unit 122 is labeled "Good" when the power at the desired port 152
of the second sensor unit 122 passes short-circuit and open-circuit
tests while providing power to the port 150 of the third sensor
unit 124.
[0071] In response to a determination that the power forwarding
status of the second sensor unit 122 is not labeled "Good", at
state 426 the sensor interface unit 102 identifies that there is a
fault in either the cable 154 between the ports of the second
sensor unit 122 and the third sensor unit 124 or in the third
sensor unit 124 itself. As a result, the sensor interface unit 102
initiates fault recovery logic at state 442.
[0072] In response to a determination that the power forwarding
status of the second sensor unit 122 is labeled "Good", at state
428 the sensor interface unit 102 determines if the third sensor
unit 124 has powered up appropriately. If powered up appropriately,
the sensor interface unit 102 receives a signal from the sensor
control processor 204 of the third sensor unit 124 indicating as
such. In response to a determination that the third sensor unit 124
has not powered up appropriately, at state 430 the sensor interface
unit 102 identifies that the third sensor unit 124 itself has
failed. As a result, the sensor interface unit 102 initiates fault
recovery logic at state 442.
[0073] In response to a determination that the third sensor unit
124 has powered up appropriately with power from the second sensor
unit 122, at state 432 the sensor interface unit 102 sends a
control signal to the third sensor unit 124, enabling power
forwarding in the third sensor unit 124. In response to the power
forwarding command from the sensor interface unit 102, the third
sensor unit 124 provides power to the fourth sensor unit 126 as
similarly described above with regards to FIG. 3. At state 434, a
determination is made whether the power forwarding status of the
third sensor unit 124 is labeled "Good". As described above with
regards to FIG. 3, the power forwarding status of the third sensor
unit 124 is labeled "Good" when the power at the desired port 152
of the third sensor unit 124 passes short-circuit and open-circuit
tests while providing power to the port 150 of the fourth sensor
unit 126.
[0074] In response to a determination that the power forwarding
status of the third sensor unit 124 is not labeled "Good", at state
436 the sensor interface unit 102 identifies that there is a fault
in either the cable 154 between the ports of the third sensor unit
124 and the fourth sensor unit 126 or in the fourth sensor unit 126
itself. As a result, the sensor interface unit 102 initiates fault
recovery logic at state 442.
[0075] In response to a determination that the power forwarding
status of the third sensor unit 124 is labeled "Good", at state 438
the sensor interface unit 102 determines if the fourth sensor unit
126 has powered up appropriately. If powered up appropriately, the
sensor interface unit 102 receives a signal from the sensor control
processor 204 of the fourth sensor unit 126 indicating as such. In
response to a determination that the fourth sensor unit 126 has not
powered up appropriately, at state 440 the sensor interface unit
102 identifies that the fourth sensor unit 126 itself has failed.
As a result, the sensor interface unit 102 initiates fault recovery
logic at state 442.
[0076] The powering of the first sensor string 112 as described
above with regards to FIG. 4 may also be applied to other sensor
strings (e.g., the second, third and fourth strings 114, 116, 118)
coupled to other ports of the sensor interface unit 102. Also,
according to one embodiment, the powering of a sensor string as
described above with regards to FIG. 4 may also utilize two levels
of over-current protection, as described above, when providing
power from one sensor to another within a sensor string.
[0077] By "walking out" power along each sensor string (i.e.
powering up individual sensor units along each sensor string one
sensor unit at a time), the sensor interface unit 102 is able to
identify the specific location of a fault within the sensor string
(e.g., in a cable or in a sensor unit itself). In response to
identifying the location of a fault, the sensor interface unit 102
is also able to recover from an identified fault as a result of the
redundant configuration of each sensor loop 156, 158. For example,
in a "normal" configuration where each sensor unit 120-148 of each
sensor string 112-118 is powered and working appropriately, each
sensor string 112-118 operates independently and redundant power
and network connectivity is not provided between strings 112-118
(i.e. the fourth sensor unit 126 does not provide power or data to
the eight sensor unit 134, and the twelfth sensor unit 142 does not
provide power to the sixteenth sensor unit 148). However, upon
detection of a fault, redundant power and network connectivity may
be provided between sensor strings 112-118 using fault recovery
logic.
[0078] FIG. 5 illustrates a state diagram 500 of fault recovery
logic of the sensor interface unit 102. As the sensor interface
unit 102 "walks out" power to each sensor unit 120-148 (e.g., as
described above with regards to FIG. 4), the sensor interface unit
102 monitors the system 100 for faults (e.g., that a power
forwarding status of a port is not labeled "Good" and has failed as
discussed above). When a fault is identified at a specific position
in a sensor string 112-118 (e.g., in a cable 154 or sensor unit
120-148 itself), the sensor interface unit 102 identifies that
sensors beyond the location of the fault where power forwarding has
failed are not powered. The fault recovery logic attempts to power
these un-powered sensors by "walking out" power in the opposite
direction along the sensor loop 156, 158.
[0079] For example, upon entering the fault recovery logic state
442 after detecting a fault during the powering up of sensor units
128-134 in the second sensor string 114, the sensor interface unit
102 sends commands to desired sensor units to begin "walking out"
power in the opposite direction (i.e. towards the sensor interface
unit 102) along the second sensor string 114. At state 502, a
determination is made whether the fault occurred in the second
sensor string 114 before the eighth sensor unit 134. In response to
a determination that the failure did not occur before the eighth
sensor unit 134 in the second sensor string 114, the sensor
interface unit 102 returns to the fault recovery logic at state
442.
[0080] In response to a determination that the failure did occur in
the second sensor string 114 before the eighth sensor unit 134, at
state 504 the sensor interface unit 102 sends a command to the
fourth sensor unit 126 enabling power forwarding of the fourth
sensor unit 126. In response to the command from the sensor
interface unit 102, the fourth sensor unit 126 provides power to
the eighth sensor unit 134 via the cable 155, as similarly
discussed above.
[0081] At state 506, a determination is made whether the power
forwarding status of the fourth sensor unit 126 is labeled "Good".
As described above, the power forwarding status of the fourth
sensor unit 126 is labeled "Good" in response to positive
short-circuit and open-circuit test results at the second port 152
of the fourth sensor unit 126. At state 508, in response to a
determination that the power forwarding status of the fourth sensor
unit 126 is not "Good", the sensor interface unit 102 identifies
that a fault exists in either the cable 155 between the fourth
sensor unit 126 and the eighth sensor unit 134 or in the eighth
sensor unit 134 itself. As a result, the sensor interface unit 102
initiates fault recovery logic at state 442.
[0082] In response to a determination that the power forwarding
status of the fourth sensor unit 126 is labeled "Good", at state
510 the sensor interface unit 102 determines if the eighth sensor
unit 134 has powered up appropriately. If powered up appropriately,
the sensor interface unit 102 receives a signal from the sensor
control processor 204 of the eighth sensor unit 134 indicating as
such. In response to a determination that the eighth sensor unit
134 has not powered up appropriately, at state 512 the sensor
interface unit 102 identifies that the eighth sensor unit 134
itself has failed. As a result, the sensor interface unit 102
initiates fault recovery logic at state 442.
[0083] In response to a determination that the eighth sensor unit
134 has powered up appropriately, the sensor interface unit 102, at
state 514, determines whether the fault occurred in the second
sensor string 114 before the seventh sensor unit 132. According to
one embodiment, as shown in FIG. 5, the sensor interface unit 102
may also enter state 514 directly from the fault recovery logic
state 442 (e.g., if the sensor interface unit 102 is aware, at the
time of fault, that the eighth sensor unit 134 is already being
powered appropriately from the fourth sensor unit 126 in the first
sensor string 112). In response to a determination that the failure
did not occur before the seventh sensor unit 132 in the second
sensor string 114, the sensor interface unit 102 returns to the
fault recovery logic at state 442.
[0084] In response to a determination that the failure did occur in
the second sensor string 114 before the seventh sensor unit 132, at
state 516 the sensor interface unit 102 sends a command to the
eighth sensor unit 134 enabling power forwarding of the eighth
sensor unit 134. In response to the command from the sensor
interface unit 102, the eighth sensor unit 134 provides power to
the seventh sensor unit 132 via the cable 154, as similarly
discussed above.
[0085] At state 518, a determination is made whether the power
forwarding status of the eighth sensor unit 134 is labeled "Good".
As described above, the power forwarding status of the eighth
sensor unit 134 is labeled "Good" in response to positive
short-circuit and open-circuit test results at the second port 152
of the eighth sensor unit 134. At state 520, in response to a
determination that the power forwarding status of the eighth sensor
unit 134 is not "Good", the sensor interface unit 102 identifies
that a fault exists in either the cable 154 between the eighth
sensor unit 134 and the seventh sensor unit 132 or in the seventh
sensor unit 132 itself. As a result, the sensor interface unit 102
initiates fault recovery logic at state 442.
[0086] In response to a determination that the power forwarding
status of the eighth sensor unit 134 is labeled "Good", at state
522 the sensor interface unit 102 determines if the seventh sensor
unit 132 has powered up appropriately. If powered up appropriately,
the sensor interface unit 102 receives a signal from the sensor
control processor 204 of the seventh sensor unit 132 indicating as
such. In response to a determination that the seventh sensor unit
132 has not powered up appropriately, at state 524 the sensor
interface unit 102 identifies that the seventh sensor unit 132
itself has failed. As a result, the sensor interface unit 102
initiates fault recovery logic at state 442.
[0087] In response to a determination that the seventh sensor unit
132 has powered up appropriately, the sensor interface unit 102, at
state 526, determines whether the fault occurred in the second
sensor string 114 before the sixth sensor unit 130. According to
one embodiment, as shown in FIG. 5, the sensor interface unit 102
may also enter state 526 directly from the fault recovery logic
state 442 (e.g., if the sensor interface unit 102 is aware, at the
time of fault, that the seventh and eighth sensor units 132, 134
are already being powered appropriately from the first sensor
string 112). In response to a determination that the failure did
not occur before the sixth sensor unit 130 in the second sensor
string 114, the sensor interface unit 102 returns to the fault
recovery logic at state 442.
[0088] In response to a determination that the failure did occur in
the second sensor string 114 before the sixth sensor unit 130, at
state 528 the sensor interface unit 102 sends a command to the
seventh sensor unit 132 enabling power forwarding of the seventh
sensor unit 132. In response to the command from the sensor
interface unit 102, the seventh sensor unit 132 provides power to
the sixth sensor unit 130 via the cable 154, as similarly discussed
above.
[0089] At state 530, a determination is made whether the power
forwarding status of the seventh sensor unit 132 is labeled "Good".
As described above, the power forwarding status of the seventh
sensor unit 132 is labeled "Good" in response to positive
short-circuit and open-circuit test results at the second port 152
of the seventh sensor unit 132. At state 532, in response to a
determination that the power forwarding status of the seventh
sensor unit 132 is not "Good", the sensor interface unit 102
identifies that a fault exists in either the cable 154 between the
seventh sensor unit 132 and the sixth sensor unit 130 or in the
sixth sensor unit 130 itself. As a result, the sensor interface
unit 102 initiates fault recovery logic at state 442.
[0090] In response to a determination that the power forwarding
status of the seventh sensor unit 132 is labeled "Good", at state
534 the sensor interface unit 102 determines if the sixth sensor
unit 130 has powered up appropriately. If powered up appropriately,
the sensor interface unit 102 receives a signal from the sensor
control processor 204 of the sixth sensor unit 130 indicating as
such. In response to a determination that the sixth sensor unit 130
has not powered up appropriately, at state 536 the sensor interface
unit 102 identifies that the sixth sensor unit 130 itself has
failed. As a result, the sensor interface unit 102 initiates fault
recovery logic at state 442.
[0091] In response to a determination that the sixth sensor unit
130 has powered up appropriately, the sensor interface unit 102, at
state 538, determines whether the fault occurred in the second
sensor string 114 before the fifth sensor unit 128. According to
one embodiment, as shown in FIG. 5, the sensor interface unit 102
may also enter state 538 directly from the fault recovery logic
state 442 (e.g., if the sensor interface unit 102 is aware, at the
time of fault, that the sixth, seventh and eighth sensor units 130,
132, 134 are already being powered appropriately from the first
sensor string 112). In response to a determination that the failure
did not occur before the fifth sensor unit 128 in the second sensor
string 114, the sensor interface unit 102 returns to the fault
recovery logic at state 442.
[0092] In response to a determination that the failure did occur in
the second sensor string 114 before the fifth sensor unit 128, at
state 540 the sensor interface unit 102 sends a command to the
sixth sensor unit 130 enabling power forwarding of the sixth sensor
unit 130. In response to the command from the sensor interface unit
102, the sixth sensor unit 130 provides power to the fifth sensor
unit 128 via the cable 154, as similarly discussed above.
[0093] At state 542, a determination is made whether the power
forwarding status of the sixth sensor unit 130 is labeled "Good".
As described above, the power forwarding status of the sixth sensor
unit 130 is labeled "Good" in response to positive short-circuit
and open-circuit test results at the second port 152 of the sixth
sensor unit 130. At state 544, in response to a determination that
the power forwarding status of the sixth sensor unit 130 is not
"Good", the sensor interface unit 102 identifies that a fault
exists in either the cable 154 between the sixth sensor unit 130
and the fifth sensor unit 128 or in the fifth sensor unit 128
itself. As a result, the sensor interface unit 102 initiates fault
recovery logic at state 442.
[0094] In response to a determination that the power forwarding
status of the sixth sensor unit 130 is labeled "Good", at state 546
the sensor interface unit 102 determines if the fifth sensor unit
128 has powered up appropriately. If powered up appropriately, the
sensor interface unit 102 receives a signal from the sensor control
processor 204 of the fifth sensor unit 128 indicating as such. In
response to a determination that the fifth sensor unit 130 has not
powered up appropriately, at state 548 the sensor interface unit
102 identifies that the fifth sensor unit 128 itself has failed. As
a result, the sensor interface unit 102 initiates fault recovery
logic at state 442.
[0095] As discussed above, redundant power is implemented within
the first sensor loop 156 (e.g., power from the first sensor string
112 is provided to the second sensor string 114); however,
redundant power, as described above, may also be implemented within
the second sensor loop 158 (e.g., power from the third sensor
string 116 is provided to the fourth sensor string 118) or within
another defined sensor loop (e.g., power from the first sensor
string 112 may be provided to the fourth sensor string 118 and
power from the second sensor string 114 may be provided to the
third sensor string 116). As also discussed above, power may be
provided from the first sensor string 112 to the second sensor
string 114 to form a first sensor loop 156 and from the third
sensor string 116 to the fourth sensor string 118 to form a second
sensor loop 158; however, power may also similarly be provided from
the second sensor string 114 to the first sensor string 112 to form
the first sensor loop 156 and from the fourth sensor string 118 to
the third sensor string 116 to form the second sensor loop 158.
[0096] By "walking out" power from a first sensor string to a
second sensor string in which a fault is detected, the fault
recovery logic is able to isolate the fault (e.g., the fault in a
connection or sensor unit) and provide power from the first sensor
string to the sensor units in the second sensor string that are
beyond the identified fault (i.e. coupled between the location of
the fault and the first sensor string. Also, according to one
embodiment, the implementation of redundant power as described
above with regards to FIG. 5 may also utilize two levels of
over-current protection, as described above, when providing power
from one sensor to another.
[0097] As described herein, a distributed sensor system
intelligently provides redundant power to sensor units within the
system. However, in addition to power, the distributed sensor
system may also provide redundant network connectivity to sensor
units within the system over the same Ethernet cables and ports.
For example, in one embodiment, each one of the sensor units is
provided network connectivity at both of its ports, allowing each
sensor unit to communicate with other "upstream" or "downstream"
devices within the network. If network connectivity at one port
fails, the sensor unit may still maintain a connection to other
devices in the system via the other port. According to another
embodiment, sensor units may also provide network connectivity
between sensor strings, as similar discussed above with regards to
power.
[0098] As described herein, the sensor interface unit 102 provides
power via ports 104-110 to the first sensor 120, the fifth sensor
128, the ninth sensor 136 and the thirteenth sensor 143
respectively; however, in other embodiments, the sensor interface
unit 102 may be coupled to any other sensor unit at any other point
within each sensor string.
[0099] As also described herein, each sensor unit 120 includes two
ports; however, in other embodiments, a sensor unit 120 may include
more than two ports. Also as described herein, each sensor unit 120
includes a single "upstream" port and a single "downstream" port;
however, in other embodiments, any number of ports may be
designated as "upstream" or "downstream. For example, in one
embodiment, a sensor unit 120 receiving power at a single
"downstream" port may forward the received power to multiple
"upstream" ports.
[0100] Embodiments described herein provide a system in which
devices are daisy chained together via Ethernet cables and power
provided from a source through the Ethernet cables is intelligently
passed from device to device, powering the string of devices. By
powering devices within the system as described above, the space
and weight requirements of the system may be reduced, allowing for
placement of the system in a location in which a typical PoE system
may be unworkable. In addition, according to some embodiments, the
system also provides redundant power, redundant network
connectivity, and/or automatic fault detection and isolation for
failed devices and cables.
[0101] It is to be appreciated that a daisy chained PoE system, as
described above, provides power forwarding capabilities (e.g.,
where a device may be both a supplier and consumer of power) and
dual function capabilities (e.g., where a device is capable of
being either a Powered Device (PD) or Power Sourcing Equipment
(PSE) dependent on the configuration of the system) which are both
typically not provided for in a standard PoE system. In addition,
it is also to be appreciated that the daisy chained PoE system, as
described above, may be able to operate at a voltage level (e.g.,
12, 24 or 28V) lower than the standard operating voltage range
(e.g., 37V to 57V) of a typical PoE system.
[0102] Having described above several aspects of at least one
embodiment, it is to be appreciated various alterations,
modifications, and improvements will readily occur to those skilled
in the art. Such alterations, modifications, and improvements are
intended to be part of this disclosure and are intended to be
within the scope of the invention. Accordingly, the foregoing
description and drawings are by way of example only.
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