U.S. patent number 3,921,168 [Application Number 05/434,481] was granted by the patent office on 1975-11-18 for remote sensing and control system.
This patent grant is currently assigned to Damon Corporation. Invention is credited to Robert A. Dunbar.
United States Patent |
3,921,168 |
Dunbar |
November 18, 1975 |
Remote sensing and control system
Abstract
Remote units are connected in parallel to a monitoring and
control center by a monitoring wire, a control wire, and a
plurality of signal wave carrying wires each conveying signal waves
of progressively doubled wave length. The remote units are each
coded and identified by selectively routing one or more signal
waves through an inverter at each unit so that the signal waves
trigger an AND gate in a given time slot for each remote unit.
According to the open/closed status of a switch, the triggering of
an AND gate sends a signal through the monitoring wire for each
unit in the time slot for that unit. The center sequentially
monitors each remote unit in its time slot and indicates its
status. Each remote unit may include a relay which is activated
from the center through the control wire during the time slot for
that unit. At the center a relay operated switch and a connection
may be added to enable a status of one remote unit to control
another remote unit.
Inventors: |
Dunbar; Robert A. (Swampscott,
MA) |
Assignee: |
Damon Corporation (Needham
Heights, MA)
|
Family
ID: |
23724415 |
Appl.
No.: |
05/434,481 |
Filed: |
January 18, 1974 |
Current U.S.
Class: |
340/518; 340/3.5;
340/533 |
Current CPC
Class: |
G08B
26/002 (20130101) |
Current International
Class: |
G08B
26/00 (20060101); G08B 025/00 (); H04Q
009/00 () |
Field of
Search: |
;340/408,150,151,206,163,164,167,152R ;343/6.5R ;179/65R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Habecker; Thomas B.
Attorney, Agent or Firm: Tailer; Peter L.
Claims
What is claimed is:
1. A system for monitoring remote units comprising, in
combination,
a. a center having signal wires extending therefrom, means
generating a wave signal in each of said signal wires, said wave
signals being of increasing wave lengths increasing from one of
said wires to the next by a whole multiple greater than one, flip
flops, an indicator means activated by each flip flop, a monitoring
wire connected to each flip flop and extending from said center,
and means counting wave signals and having outputs each connected
to one of said flip flops, said outputs each sending a signal to a
flip flop during a given count which is during a given time
interval; and
b. a plurality of remote monitoring units, each remote unit having
a sensing switch, gate means, inverters connected to said gate
means, means connected to each of said signal wires and being
selectively preset to route signals from each of said signal wires
directly to said gate means and alternately through one of said
inverters to said gate means, said means connected to each of said
signal wires routing signals to said gate means to code each remote
unit by causing the gate means of each remote unit to emit a signal
during a given time interval, and means connected to said
monitoring wire responsive to a position of said remote unit
sensing switch passing the signal emitted by said gate means
through said monitoring wire;
a signal in said monitoring wire and a simultaneous signal from an
output of said means counting wave signals activating each of said
flip flops to in turn activate one of said indicator means at the
center according to a position of each of said remote unit sensing
switches.
2. The combination according to claim 1 wherein said means
generating a wave signal in each of said signal wires generates
wave signals of progressively doubled wave lengths.
3. The combination according to claim 2 wherein said system is a
system for monitoring and controlling remote units; wherein in (a)
said center has multiplexing means connected to said signal wires
and having input switches, and a control wire extending from said
multiplexing means, said multiplexing means sending a signal
through said control wire in a time interval determined by the
closing of a given input switch which represents a given count of
wave signals in said signal wires; and wherein in (b) at least some
of said remote units each have a relay operated switch, and means
responsive to simultaneous signals from said gate means and said
control wire activating said relay operated switch, the operation
of a given multiplexing means input switch at said center
activating the relay operated switch of a given one of said remote
units.
4. The combination according to claim 3 wherein in (a) at least one
of said multiplexing means input switches is relay activated, and
with the addition of a connection between one of said flip flops
and said relay activated multiplexing means input switches so that
said flip flop activates the relay activated input switch, a
position of the sensing switch of one of said remote units thereby
controlling the relay operated switch of another of said remote
units.
5. The combination according to claim 2 wherein at least one of
said remote units has one of said signal wires connected through
said sensing switch of said at least one remote unit, said sensing
switch of said at least one remote unit being a single pole, double
throw switch, said sensing switch being one of said means in said
at least one remote unit selectively routing signals from said
signal wire directly to said gate means and through one of said
inverters to said gate means, said center having two indicator
means each indicating a position of said sensing switch of said at
least one remote unit.
6. The combination according to claim 5 wherein said at least one
remote unit is all said remote units, each remote unit having a
sensing switch connected to one of said signal wires, said center
having two indicator means for each remote unit, each indicator
means indicating a position of one of said sensing switches.
7. The combination according to claim 2 wherein said means
generating a wave signal in each of said signal wires is a clock,
and a binary counter having outputs, said binary counter being
connected to said clock, said signal wires each being connected to
an output of said binary counter.
8. The combination according to claim 7 wherein said means counting
wave signals is a binary to sixteen converter having inputs
connected to outputs of said binary counter, said converter having
counting outputs each connected to one of said flip flops.
9. The combination according to claim 3 wherein said means
generating a wave signal in each of said signal wires is a pulse
generating clock, and a binary counter having outputs connected to
said clock counting pulses therefrom, said signal wires each being
connected to an output of said binary counter; and wherein said
means counting wave signals is a binary to sixteen converter having
inputs connected to outputs of said binary counter, said binary to
sixteen converter having outputs each connected to one of said flip
flops.
10. The combination according to claim 9 with the addition of a
dividing element connected to said clock dividing pulses therefrom,
said dividing element strobing said binary to sixteen converter
during a central part of each wave signal.
11. The combination according to claim 2 wherein said means
connected to each of said signal wires selectively routing signals
from each of said signal wires directly to said gate means and
alternately through one of said inverters to said gate means is a
pair of jumpers connected in parallel between each signal wire and
said gate means of each remote unit, one of each of said jumpers of
each pair being connected in series with one of said inverters, one
of said jumpers of each pair being broken to selectively route wave
signals thereby coding each of said remote units.
12. A system having remote units connected in parallel and a center
to which said remote units are connected, said system comprising,
in combination,
a. a center having signal wires extending therefrom, a clock
generating pulses, a binary counter connected to said clock
counting pulses therefrom and having outputs, each of said signal
wires being connected to an output of said binary counter so that
said binary counter transmits square waves through said signal
wires of progressively doubled wave length from one wire to the
next, an additional wire, and means at said center counting wave
signals in said signal wires and being connected to said additional
wire; and
b. a plurality of remote units, each of said remote units having
gate means, inverters, means connected to each of said signal wires
selectively routing wave signals directly to said gate means and
alternately through one of said inverters to said gate means, at
least some of said means connected to each of said signal wires
coding each remote unit by causing the gate means of each unit to
emit a signal during a given time interval, and means receiving
said signal emitted from said gate means connected to said
additional wire;
said means at said center counting wave signals in said signal
wires and said means at said remote units receiving signals emitted
from said gate means interacting through said additional wire.
13. The combination according to claim 12 wherein said system is a
system having said center monitor at least some of said remote
units;
wherein in (a) said additional wire is a monitoring wire, and said
means at said center counting wave signals in said signal wires is
a binary to sixteen converter having inputs connected to said
outputs of said binary counter, said converter having outputs; and,
wherein in (b) said means receiving said signal emitted from said
gate means transmits the signal through said monitoring wire;
and
with the addition of in (a) flip flops at said center each
connected to an output of said binary to sixteen converter and each
connected to said monitoring wire, and an indicator means connected
to each flip flop activated by each flip flop; and with the
addition of in (b) a sensing switch at each remote unit controlling
the emission of a signal from said gate means so that each of said
flip flops activates an indicator means according to a position of
a given remote unit sensing switch.
14. The combination according to claim 13 wherein said sensing
switch in at least one of said remote units is one of said means
selectively routing signals from said signal wires, said sensing
switch at said at least one remote unit being a single pole double
throw switch, an indicator at said center indicating each position
of the sensing switch of said at least one remote unit.
15. The combination according to claim 13 wherein said system is a
system having said center monitor and control said remote
units;
with the addition of in (a) a multiplexer having input switches,
and a control wire, said multiplexer sending a signal through said
control wire on the closing of a given input switch during the time
interval of a given count of wave signals by said multiplexer; and
with the addition of in (b) relay operated switches in said remote
units activated from said center, and means in said remote units
responsive to simultaneous signals from said gate means and from
said control wire activating said relay switches on the operation
of said multiplexer input switches.
16. The combination according to claim 15 wherein in (a) at least
one of said multiplexer input switches is relay activated, and with
the addition of a connection between one of said flip flops and
said relay activated multiplexer input switch so that said flip
flop activates said relay activated multiplexer input switch, a
position of the sensing switch of one of said remote units thereby
controlling the relay operated switch of another of said remote
units.
17. The combination according to claim 12 wherein said system is a
system having said center control at least some of said remote
units;
wherein in (a) said means at said center counting waves in said
signal wires is a multiplexer having input switches, and said
additional wire is a control wire, said multiplexer sending a
signal through said control wire on the closing of a given input
switch during the time interval of a given count of wave signals
determined by that input switch; and, with the addition of in (b) a
relay operated switch in each remote unit activated from said
center; and wherein in (b) said means responsive to a signal
emitted from said gate means in said remote units controlled from
said center responds only during a simultaneous receipt of signals
from said control wire and said gate means to activate relay
switches of remote units.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention:
In modern high rise buildings there is a great need to collect
information at remote sensing units at a control center from which
remotely controlled units may be activated. The information may be
collected from smoke detectors, heat sensitive switches, security
devices, switches activated by the opening of doors, and the like.
In response to this information, remote units such as alarms, stair
well pressurizing blowers, and the like must be activated. In
hospitals, remote patient call buttons are monitored. In factories
and stores security requires the central monitoring of security
devices on doors, windows, and the like.
2. Description of the Prior Art
Heretofore each remote sensing and control unit had its own set of
wires run directly to a central monitoring and control center. This
invention allows the parallel connection of all remote units with
relatively few wires to a monitoring and control center.
SUMMARY OF THE INVENTION
A monitoring and control center for a plurality of remote units has
a binary counter into which regular clock pulses are fed to
generate square wave signals of progressively doubled wave length,
each wave signal being sent through a separate wave signal carrying
wire. A plurality of remote units are connected in parallel to the
center by the signal wave carrying wires, a monitoring wire, and a
control wire. The number of remote units monitored and controlled
may be as many as 2.sup.n where n is the number of wave signal
carrying wires.
The remote units are each keyed as to their identity and thus their
location by selectively breaking one of a pair of jumpers, one of
each pair being in series with an inverter, each pair of jumpers
being connected to a signal wire so that one or more wave signals
at each remote unit may be selectively inverted. These selectively
inverted signals at each unit are fed to an AND gate which emits a
signal in a given time slot for each unit. A monitoring signal is
only sent from a given unit to the center if a switch at the remote
unit is operated. Smoke detectors, door switches, and the like
operate the switches at each remote unit. The coding of
identification of the units limits their monitoring signal output
to a given time interval because the inversion of one or more
combinations of progressively doubled wave length signals
determines the time interval when all the wave signals will be high
and it is only when all the inputs to a given AND gate are high
that it will cause a monitoring signal to be emitted.
At the center, a binary to sixteen converter is connected to the
wave signal carrying wires and has its outputs each connected to
the gate of a flip flop associated with a lamp for each remote
unit. The monitoring wire is connected to all the data inputs of
the flip flops and the output of each flip flop activates a lamp.
Therefore when a monitoring signal is sent from a given remote unit
in its coded time slot, the monitoring signal reaches all the flip
flops, but only one flip flop receives a gating signal from the
binary to sixteen converter during that time slot to light its
associated indicator lamp. Thus the closing of a sensing switch on
a given remote unit will be indicated at center by the lighting of
a given lamp.
If a multiplexer at center is also connected to the signal wave
carrying wires, switches to its inputs corresponding to each remote
unit can be closed to send a control signal to all the remote units
through the control wire. However, the multiplexer will only send a
control signal in the time slot of a given unit whose multiplexer
input switch is closed at center. In a unit a signal from its AND
gate and a control signal can be used to activate a relay to sound
an alarm, close a door, or carry out any other remote control.
At central, the output from any flip flop can activate one or more
switches of the multiplexer. This enables a remote unit to sense a
condition and then control one or more other remote units.
Additionally, a single pole double throw switch at a remote unit
can be used to connect a signal wave carrying wire directly or
through an inverter to the AND gate of the remote unit. The double
throw switch is moved by the sensing means at the remote unit. The
rest of the signal wave carrying wires are used to selectively code
a unit as has been described. While this embodiment of the
invention requires an extra wave signal carrying wire and two
indicator lamps at center for each remote unit, one lamp may be
used to indicate that a given remote unit is connected to central
and the other lamp will indicate that the unit has been activated
by a sensing device.
Thus it may be seen that the remote monitoring and control system
of this invention is easy to install as the center is connected
with relatively few wires in parallel to a large number of remote
units. Since the remote units are all identical, they are
inexpensive to fabricate and may be coded on installation. The
center is simple although it handles a large number of remote units
and may be modified, even after installation, to enable one remote
unit to control other remote units by its activation. The center
may also display information indicating that units, although not
activated, have failed to function.
The remote units may be activated by smoke detectors, heat sensors,
door position switches, and any other devices. In a like manner,
there is no limit to the control functions they may carry out if
provided with control relays. The system of this invention has
almost unlimited uses. It has been tested in building security
applications.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a monitoring and control center
connected to two remote units, one unit being a remote sensing unit
and the other being a remote sensing and control unit;
FIG. 2 is an enlarged diagram of an AND gate with pairs of jumpers
connected thereto as in a remote unit, one jumper of each pair
being broken to code the unit;
FIG. 3 is a time interval graph of signal waves carried by the
wires A, B, C, and D of FIG. 1;
FIG. 3A is a time interval graph of signal waves carried by a data
line, the wire A, and the strobe line;
FIG. 4 is a column showing the status of outputs of the binary
counter of FIG. 1 during a number of clock pulses;
FIG. 5 is a time interval graph of signal waves in a remote unit
coded to invert the signal waves from wires B, C, and D, the waves
being shown prior to their entering the AND gate of that unit;
FIG. 6 is a block diagram of elements broken away from FIG. 1 and
modified so that a remote sensing unit may activate another remote
sensing and control unit; and
FIG. 7 is a block diagram of a monitoring center and remote sensing
units, the center having two indicating lamps for each remote unit,
one lamp indicating that a unit is connected and functioning and
the other lamp indicating that the unit has been activated.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A monitoring and control center is generally designated by the
reference numeral 9 and comprises the elements shown in the upper
half of FIG. 1. Within center 9 clock 10 passes pulses at a given
frequency through the divide by eight element 13 to binary counter
14 by means of the leads 11 and 12. Lead 15 from one of the central
outputs of element 13 strobes binary to sixteen converter 16 and
multiplexer 65 if it is used. The outputs A", B", C", and D" of
binary counter 14 are connected to the signal wires A, B, C, and D,
respectively, as well as to the inputs A', B', C' and D' of the
binary to sixteen converter 16. The numbered outputs 0-15 of the
binary to sixteen converter 16 are connected, respectively, to the
flip flops F 0-15 by the leads 20-35.
A remote sensing unit 40 has pairs of jumpers 41-48 connected to
signal wires A, B, C, and D by leads 36-39. One jumper 42, 44, 46,
and 48 of each pair is connected in series with an inverter 50, 51,
52 and 53. Output from the pairs of jumpers are connected to the
multiple inputs of AND gate 54. FIG. 2 shows an enlarged view of
the pairs of jumpers 41-48 connected to the AND gate 54 of a remote
unit 40.
Referring now to FIGS. 3 and 4, output A" of binary counter 14,
which is connected to signal carrying wire A, is pulled low and
then goes high changing its condition to count successive pulses
from divide by eight element 13. Output B" connected to signal wire
B is pulled low for two pulses and then goes high for two pulses;
output C" connected to signal wire C is pulled low for four pulses
and then goes high for four pulses; and output D" connected to
signal wire D is pulled low for eight pulses and then goes high for
eight pulses. These outputs of binary counter 14 generate the
square waves shown in FIG. 3 and sent through the wave carrying
wires A, B, C and D.
The state of the binary counter outputs is also shown in FIG. 4, 0
representing a low state and 1 a high state. These states, as in
any binary counter, correspond to the columns of binary numbers
shown in FIG. 4 after their decimal equivalents. As has been
stated, these states of the outputs A", B", C" and D" corresponding
to binary numbers generate the square waves shown in FIG. 3, each
wave signal being twice the wave length of an adjacent wave
signal.
FIG. 3A shows the sort duration strobe pulses in line 15 that
trigger the binary to sixteen converter 16 and multiplexer 65 in a
central portion of the square waves generated by the binary counter
14. The data line signal is shown as if a remote unit 40 was coded
to send a signal in the 0 time slot as will be hereinafter
explained.
Remote unit 40, as shown in FIG. 1 and elements of which are shown
in FIG. 2 is specifically coded by breaking the jumpers 41, 43, 45,
and 47 so that the signal waves in the wires A, B, C, and D are
inverted to enter the AND gate 54. As shown in FIG. 3, the only
time interval when all signal waves are low is during the first
time interval designated 0. Thus in this time interval and only in
this time interval, since unit 40 is coded to invert all signal
waves, AND gate 54 of remote unit 40 passes a signal through lead
55 to AND gate 56. If switch 57 is closed by a remote sensing
element, the thus grounded lead 58 connected to gate 56 will cause
it to send a monitoring signal through lead 59 connected to the
monitoring wire 60.
Referring further to FIG. 1, wire 60 is connected to all the flip
flops F, but it is only during time interval 0 that the binary to
sixteen converter 16 sends a signal through its 0 output to trigger
the 0 flip flop F and light lamp 61 which is connected to a
potential by lead 62. If switch 57 of remote unit 40 is not closed,
no monitoring signal will be sent through monitoring wire 60 during
time interval 0 to light lamp 61.
During the second time interval, which is designated 1 in FIG. 3,
the binary counter output A" goes high. A remote unit, not shown,
could be coded for time interval 1 by breaking its jumpers 41, 43,
45 and 48. As shown in FIG. 1, remote unit 40', except for some
added control elements, is identical with remote unit 40. Remote
unit 40' is specifically coded by breaking its jumpers 42, 44, 46
and 47 so that the wave signal in wire A is inverted and the wave
signals in wires B, C and D are not inverted to enter AND gate 54'.
The signal waves entering AND gate 54' are shown in FIG. 5. In this
altered situation, it may be seen that the all signals high time
interval is now shifted into the time interval designated 14. For
this reason it is only during time interval 14 that remote unit 40'
will send a monitoring signal through lead 59' to monitor wire 60
if its switch 57' is closed. Since it is only during time interval
14 that the binary to sixteen converter 16 will send a signal to
flip flop F 14 through lead 34, the closing of switch 57' of remote
unit 40' can only light indicator lamp 64. As shown, after one
hundred twenty eight pulses from clock 10 and sixteen pulses from
element 13, the outputs of binary counter 14 will all go low again
to monitor unit 40 a second time and continually at intervals as
the clock pulses are generated.
Referring further to FIG. 1, with four signal wave carrying wires
A, B, C, and D, the status of sixteen remote units 40 or 40' can be
monitored, each unit being coded by breaking different combinations
of its jumpers 41-48 to have each unit send its monitoring signal
in its own one of the sixteen available time slots. If the binary
counter 14 and the binary to sixteen converter 16 are cascaded or
otherwise provided with increased capacity, the number of remote
units 40 or 40' which may be monitored, each with its own indicator
lamp L at the center 9, is equal to 2.sup.n, where n is the number
of signal carrying wires provided. For each additional signal
carrying wire, another pair of jumpers and an inverter must be
provided in all the remote units.
In one test installation clock 10 provided 8,000 pulses per second.
Eight wave carrying signal wires were provided to allow for a
maximum of two hundred and fifty six remote units which were all
selectively coded by breaking one jumper of each of eight pairs of
jumpers in each unit. Since there were 256 time slots, one for each
remote unit, each unit was monitored with the 8,000 pulses per
second of the clock every quarter of a second. Additional signal
wires and many more remote units can be used. If required, clock
pulses can be provided at higher rates so units will be monitored
at closer intervals of time. The divide by eight element 13 strobes
binary to sixteen converter 16 near the center of each signal wave
to prevent the possibility of false signals at the start of end of
a pulse. Well known solid state and integrated circuit elements are
used as is well known in the art.
Referring further to FIG. 1, if it is desired to control a device
connected through the relay 75 of a remote unit 40', a multiplexer
65 is provided at center 9. Inputs A.sub.1, B.sub.1, C.sub.1, and
D.sub.1 of multiplexer 65 are connected to signal wires A, B, C,
and D by the leads 66-69, respectively. When a given grounded
switch 70 connected to one of the multiplexer 65 inputs 0-15 is
closed, multiplexer 65 will send a control signal through control
wire 71 which would be connected to all the remote monitoring and
control units 40'. The control signal will be sent in the time
interval determined by which of the switches 70 is closed. As
shown, closing switch 70 to ground multiplexer 65 input 1 causes
multiplexer 65 to send a signal through control wire 71 and lead 72
to AND gate 73 in time interval 1. As unit 40' is coded to time
interval 1 as has been described, simultaneous signals reach gate
73 through leads 72 and 74. This activates relay 75 to remotely
control any desired device connected through relay 75.
Referring now to FIGS. 1 and 6, the multiplexer 65 of FIG. 1 is
replaced in FIG. 6 by a substantially identical multiplexer 65'
having a relay activated grounded switch 76 connected to one of its
inputs, the input 0 as shown. A connection 77 from the output of
flip flop F 3 causes its activation to close the relay operated
grounding switch 76. Thus it may be seen that the activation of any
remote unit 40 or 40' can be used to control any other remote unit
40'. If desired, a plurality of connections may be made between one
flip flop output and a number of relay activated grounding switches
76. Thus by merely making a number of connections at the center 9,
the activation of some remote units may control others
automatically. The relay activated grounding switch 76 may be any
solid state equivalent thereof.
Referring now to FIG. 7, a monitoring center 9' which could also be
a monitoring and control center 9 if desired, has sixteen indicator
lamps L, a clock 10, a binary counter 14, a binary to sixteen
converter 16, and four wave carrying signal wires A, B, C, and D.
Center 9' is substantially identical to center 9 of FIG. 1 except
that pairs of lamps L monitor the state of each remote unit 80.
Thus the center 9' can only monitor eight remote units 80 with four
wave carrying wires.
The units 80 are identical, each having three pairs of jumpers 81,
82, 83, 84, 85 and 86 connected to the signal wires B, C, and D by
the leads 87, 88 and 89, respectively. Inverters 91, 92, and 93 are
connected in series with the jumpers 82, 84 and 86. A single pole,
double throw switch 90 is thrown at each remote unit 80 by a
sensing element. The switches 90 in the units 80 are connected to
wire A by leads 94. In one position switch 90 directs signals to
lead 95 and in the other position it directs signals through an
inverter 96 to lead 95. When all signals are high entering the AND
gate 97 of each unit 80, gate 97 sends a signal through a lead 98
to monitoring wire 60.
The uppermost unit 80 is shown coded by breaking jumpers 81, 83,
and 85 which codes this unit 80 to the time intervals 0 or 1; the
center unit 80 is shown coded by breaking jumpers 82, 83 and 85
which codes this unit 80 to the time intervals 2 or 3; and the
lowermost unit 80 is shown coded by breaking jumpers 81, 84, and 85
which codes this unit 80 to the time intervals 4 or 5. Additional
units 80 would be coded to following pairs of time intervals.
The switch 90 of the uppermost unit 80 has not been moved to invert
signal waves in wire A so that this unit 80 now lights lamp 101 in
time interval 1. Lamp 101 being lit indicates at center 9' that
proper connections are made to this unit 80 and that it is coded
and functioning. If this switch 90 was moved by a sensing element
to invert the signal waves in wire A by passing them through
inverter 96, lamp 100 would light as flip flop F O was activated in
time interval 0. Thus lamp 100 lights to show that a sensing
element has thrown switch 90 of the uppermost unit 80.
The switch 90 of the center unit 80 is shown moved by a sensing
element to invert the signal in wire A and cause lamp 102 to light
of the second pair of lamps 102 and 103. The switch 90 of the
lowermost unit 80 is shown not moved by a sensing element so that
the signal in wire A is not inverted. This unit 80 lights lamp 105
of the next pair of lamps 104 and 105. With the addition of the
elements shown in unit 40' in FIG. 1, lead 74, gate 73, and relay
75, the units 80 could be made as monitoring and control units. In
this embodiment of the invention, one signal wire is used to
indicate the positions of the switches 90 and only the remaining
signal wires provide signals which are used in the units 80 to code
them for their identification.
While this invention has been shown and described in the best forms
known, this is purely exemplary and many modifications and
substitutions may be made. For example, the breaking of one of each
of the pairs of jumpers in the remote units is shown as a means to
code the remote units. However, any equivalent means may be used
which selectively inverts the wave signals entering the AND gates
of the units. Other than lamps, many different indicating devices
may be used in the center. Equivalents which perform the same
function may be substituted for all the element of the center and
the remote units. While a binary counter is shown generating square
wave signals in response to clock pulses, square waves need not be
used. Further, the square signal waves have been shown as having
progressively doubled wave lengths; however, with suitably
manipulated coding of the remote units and the sacrifice of some
potentially usable time intervals, signal wave lengths may be
progressively increased by factors other than two. Elements of the
several embodiments of this invention can be combined in a given
system.
* * * * *