U.S. patent number 3,581,289 [Application Number 04/819,701] was granted by the patent office on 1971-05-25 for display terminal for computer monitored plant variables.
This patent grant is currently assigned to Owens-Illinois, Inc.. Invention is credited to D. L. Bissell, George M. Lambroff, Peter S. Miller, D. F. Wilhelm.
United States Patent |
3,581,289 |
Wilhelm , et al. |
May 25, 1971 |
DISPLAY TERMINAL FOR COMPUTER MONITORED PLANT VARIABLES
Abstract
Input variables are sensed by sensors at various locations in a
manufacturing facility and supplied as raw data to a computer which
may or may not perform calculations on the data supplied thereto.
Data from the computer is presented on a time sharing basis to a
plurality of remotely located data display terminals. Each data
display terminal is equipped with a plurality of manually actuated
data selection units having identifying indicia and a numerical
display displaying data from the computer corresponding to the
requested indicia of an actuated data selection unit along with
data indicating trend of the variable relative to a standard or
reference value. The communication link between the computer and
the display terminals may be conventional wiring with data lines
common to each display terminal and individual lines for achieving
connection to the computer and the display terminal being
individual to the display terminals. Consult the specification for
further features and details.
Inventors: |
Wilhelm; D. F. (Toledo, OH),
Miller; Peter S. (Toledo, OH), Bissell; D. L. (Toledo,
OH), Lambroff; George M. (Swanton, OH) |
Assignee: |
Owens-Illinois, Inc.
(N/A)
|
Family
ID: |
25228813 |
Appl.
No.: |
04/819,701 |
Filed: |
April 28, 1969 |
Current U.S.
Class: |
700/17 |
Current CPC
Class: |
G06F
3/0489 (20130101); G06F 3/0219 (20130101) |
Current International
Class: |
G06F
17/40 (20060101); G06F 3/023 (20060101); G06f
003/00 (); G06c 021/00 () |
Field of
Search: |
;340/172.5,153,324
;235/145,146 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
IBM 2250 Display Unit Model 2 Reference Manual, 1966 pp.
7--16.
|
Primary Examiner: Henon; Paul J.
Assistant Examiner: Chapuran; R. F.
Claims
We claim:
1. In combination, apparatus for displaying to a plurality of
remote data display stations plant operating data as produced by a
computer connected to monitor a plurality of variable data inputs
from a plurality of data monitors located in the plant
a plurality of manually actuated data pushbutton selection means
arrayed in a logical matrix, each pushbutton selection means having
indicia thereon corresponding to a variable data input to the
computer and first lamp means behind each indicia for lighting
same,
memory-switch means associated with each selection means for
deenergizing all lamps behind the indicia in the pushbuttons in the
array and then energizing the lamp behind an indicia on a
pushbutton which has been manually actuated,
encoding matrix means connected to said plurality of pushbutton
selection means for encoding the column and row position of said
pushbutton selection means which has been actuated,
request means at each remote terminal for interrogating the
computer for service,
a communication link for conveying signals produced at each remote
station to said computer,
means at the computer for transmitting a signal to the remote data
terminal at which said pushbutton has been depressed to cause the
data signal from said encoding matrix to be transmitted to the
computer,
means at the computer for receiving said transmitted data and
delivering signals corresponding to the requested data via said
communication link to said remote data terminal in code,
means at said remote data terminal for decoding the received data
signals and producing display data corresponding thereto, and
means at the remote data terminal for displaying the decoded
display data received from the computer.
2. The invention defined in claim 1 wherein the data transmitted
from the computer to the remote data terminal includes
a signal indicating the directional trend of the data transmitted,
and
second lamp means at the remote data terminal for displaying the
directional trend of the data.
3. The invention defined in claim 1 wherein said request means at
each remote terminal includes visible signal means operated by
signals from the computer to indicate that the data terminal at
which a request has been initiated is connected to receive data
from the computer.
4. In combination, a system for displaying to a plurality of remote
data display stations plant operating data produced by a computer
connected to monitor a plurality of data inputs, a plurality of
data monitors located in the plant and connected to said computer,
a communication link common to said data display stations and in
which data from the computer is individually displayed by data
display means at the station requesting same, means at all remote
data display stations for preventing the data display means thereof
from responding to data on said communication link destined for
another remote data display station, and means preventing
transmission of signals corresponding to information signals to
said computer until the computer has completed transmission of data
destined for another remote station.
5. In combination with a data display terminal for interrogating a
plant monitoring computer and displaying plant operating data
received from the computer, said display terminal including a
plurality of pushbutton data selection means arrayed in horizontal
rows and vertical columns, each pushbutton having unique indicia
thereon corresponding to variable plant operating data available
from the computer, the improvement comprising
memory-switch means operatively associated with each
pushbutton,
each said memory-switch means including a normally open solid state
switch and means supplying operating potentials thereto which is
common to normally open solid-state switch means of all
memory-switch means, and
means operated on actuation of one pushbutton in the array for
momentarily removing the operating potentials supplied to all said
normally open solid state
6. The invention defined in claim 5 wherein said memory-switch
includes
a silicon controlled rectifier, and
a normally open switch connected between the gate electrode of said
silicon controlled rectifier and said supply of operating
potential.
7. The invention defined in claim 5 wherein said means operated on
actuation of one pushbutton in the array for momentarily removing
the operating potential supplied to all said normally open solid
state switch means to actuate same includes
a normally closed switch, there being one normally closed switch
for each pushbutton in the array,
means connecting all of said normally closed switches in
series,
a pulse forming circuit,
means connecting said series connected normally closed switches to
said pulse forming circuit to cause said pulse forming circuit to
produce a pulse upon any one of said normally closed switches being
open, and
switch means operated by any pulse so produced for removing the
operating potential from said memory-switch means.
8. The invention defined in claim 5 wherein said pulse operated
switch is constituted by a current regulating transistor in said
means supplying operating potential.
9. The invention defined in claim 5 wherein each said pushbutton
includes a lamp for lighting said indicia and wherein each such
lamp is supplied with operating current through said memory-switch
means associated with its respective pushbutton.
10. The invention defined in claim 7 wherein the data display for
said data display terminal is constituted by a plurality of decimal
readout devices, and further including means responsive to a pulse
produced by said pulse forming circuit to cause all said decimal
readout devices to exhibit the digit "0."
11. The invention defined in claim 10 wherein said plurality of
decimal readout devices exhibit data on a common screen and wherein
signals received from said computer include a signal corresponding
to the trend of the variable data to be displayed, and further
including means for providing a background color on said screen
indicative of said trend.
12. The invention defined in claim 9 wherein each pushbutton
includes a second lamp, and means responsive to signals from said
computer for energizing a selected second lamp independently of the
energization of said first lamp.
13. The invention defined in claim 12 including means responsive to
signals from said computer for deenergizing any selected second
lamp.
Description
This invention relates in general to improvements in remote data
display terminals for displaying data from a computer monitoring a
manufacturing facility.
Proper control of modern industrial plants requires that production
variables be presented to plant operators and management personnel
requesting same in as expeditious and economical a manner as
possible. There are presently available numerous forms and systems
for accomplishing this objective. The present invention is directed
to a unique data display terminal to allow operators and management
personnel at various near and distant stations to quickly and
simply obtain information that is available in a central computer
to which information, raw data, etc., is supplied from sensors and
other monitoring devices located at various stations and machines
in the manufacturing facility. (Of course, the data may be entered
into the computer manually.) For example, in a bottle manufacturing
assembly line, the operation of the numerous bottle forming
machines, glass furnace temperatures, bottle flow rates, and the
like, are supplied to the computer which may or may not perform a
computation. For example, the computer may simply store the data
for display to interested personnel. If a particular bottle forming
machine or plant or portion thereof is for some reason operating
below standard or normal production rates, which may be stored in
the computer, the actual production rate may be measured and
compared with the standard by the computer to produce a signal
indicating that the production is normal or that it is below normal
in trend. The present invention combines the function of simplified
instruction with a numerical readout and alarm display on a data
display terminal which time shares common data lines with a number
of other such data display terminals.
In general, the system comprises one or more remote data display
terminals, a set of data lines and a set of digital inputs at the
computer. The data display terminal contains a decimal display (one
or more units), an array of data selection units such as
pushbuttons with two lamps (red and white) behind each pushbutton,
and a "request" pushbutton (with lamp), and a separate indicator
lamp. Each of the buttons in the array (one for each terminal
panel) represents an instruction to the computer; e.g., "obtain and
display the current value of a certain variable." When one of these
buttons is pressed, its internal white lamp is lit (and any other
white lamp on the panel which was previously lit goes out), and a
memory unit associated with the pushbutton is actuated. A
communication to the computer is initiated by pressing the request
button to light its lamp and signals the computer that:
1. a request for service has been made (a priority level is
inherent in the request so that the computer may decide whether to
service it or defer servicing until an activity of high priority is
completed), and
2. the request comes from this particular panel; e.g., the computer
identifies the remote terminal requesting information. The computer
then signals the particular terminal to "latch on" to the data
lines so that it can respond to the information on the data lines
from the computer whereby the terminal's instruction will appear on
the data lines to the computer. At this time, the lamp in the
isolated button goes out and the indicator lamp is lit.
The computer then reads the instruction from the terminal, and its
response will place instructions on the data lines from the
computer that will place its number (or other message) in the
decimal display and turn on any or all of the red lamps in the
pushbutton array. The decimal message may be the value of the
variable and the red lamp can be used as warning for alarm signals
associated with each of several conditions or variables. For
example, in the event the particular variable being monitored is
the temperature of a glass furnace and the temperature is abnormal,
the red lamp behind the decimal display will be lighted, and the
decimal display would be presented with a red background to
indicate the abnormal condition.
The computer unlatches the terminal (and the indicator lamp goes
out) and proceeds to service other data terminals in the same way
while the numbers and signals that were posted at the previously
served data display terminal are continuously displayed. It will be
apparent that the apparatus and system disclosed herein permits as
many points per terminal as required;
that each terminal provides its own memory;
that each terminal time shares a main cable or communication link
to the computer;
that each terminal utilizes binary code to decimal conversions to
conserve wires;
that each terminal incorporates an alarm indication; and
that each unit is simple to operate and understand by operating
personnel.
If desired, the computer may be programmed to simultaneously,
selectively, or sequentially control the remote terminals to update
variable data, trends (alarms), etc. The variables displayed at one
terminal need not be the same as those displayed at other
terminals.
Objects of the present invention are to provide: remote data
display terminals for displaying computer information which have an
internal memory and which provide a sustained display by virtue of
its own memory system; and combinations of functions of simplified
instruction, numerical readout and alarm display on one remote data
terminal which time shares common data lines from the computer with
other remote data terminals.
These and other advantages and features of the invention will
become more apparent and better understood from the following
description when read in conjunction with the accompanying drawings
wherein:
FIG. 1A is a block diagram illustrating the overall system; and
FIGS. 1B and 1C illustrate the request unit and one of the data
selection pushbuttons at a remote date display terminal;
FIG. 2 is a wiring diagram illustrating the sharing of common data
lines and the control and information flow lines;
FIG. 3 is a block diagram of circuitry at each remote data display
unit;
FIG. 4 is a partial circuit schematic illustrating the memory and
encoding circuit at each remote data display terminal;
FIG. 5 is a partial circuit schematic illustrating the manner in
which actuation of any data selection unit clears the memory units
of all data selection units and produces a control pulse for
clearing the display for the newly requested information;
FIG. 6 is a partial block diagram illustrating the manner in which
input data from the computer is decoded to produce the digital
display of data at the remote data display terminals;
FIG. 7 is a block diagram of the circuit for driving the trend
indicating lamps (red and green) forming the background for the
digital data display; and
FIG. 8 is a block diagram illustrating the decoding circuit for the
alarm lamps at each data selection unit pushbutton.
With reference to FIG. 1 of the drawings, data sources 10
constituted by data sensors or monitors 10-1, 10-2,..... 10-11, at
various locations in the plant feed raw data to computer 11, which
may be a general purpose digital computer programmed to receive and
perform calculations on the raw data or store the data for
transmission to a remote station on request. A distribution bus 12
contains data lines (FIG. 2) that are shared by a plurality of
remote data display terminals RDS.sub.1, RDS.sub.2... RDSn
connected to the distribution bus by lines 13, 14 and 15
respectively. An operator selects one of the variables for display
on digital display screen 17 by actuating one of the data selection
units, e.g., pushbuttons 200 at his display terminal. Actuation of
the one selection unit returns all the digital display on the
screen to an initial or zero display, restores all memory units to
an initial nonactuated state and then sets a memory unit for
storing the request information for transmission to computer 11.
The operator then actuates a request unit 250 (see FIG. 1B) which
transmits a signal to the computer from his terminal. Computer 11
determines which of remote data display stations RDS has signaled
and, as described later herein, latches that station onto the data
lines in distribution bus 12. Any alarm signals for lighting a red
lamp at each data selection unit 200 (FIG. 1C) and the current
value of the variable requested are transmitted to the station
which is latched onto the data lines of the distribution bus 12.
The computer 11 may be programmed to automatically update numerical
display and alarms on each terminal RDS.sub.1 RDS.sub.2 ...RDSn on
a periodic basis.
FIG. 2 shows the actual wiring connections from computer 11 to the
various remote data display terminals (the arrows indicating
direction of data flow). The upper lines (pairs) are used to
transmit variable data to the remote data display units while the
lower lines are used to transmit request data from the stations to
the computer. Except for the lines labeled Ri, Ri.sub.2... Ri.sub.n
and Si.sub.1, Si.sub.2... Si.sub.n. All lines are common to all
terminals. Lines Si.sub.1, Si.sub.2... are unique to each station
and serve to identify the terminal requesting service to the
computer and the lines Ri.sub.1, Ri.sub.2... Ri.sub.n are likewise
unique to each station and serve to cause the latching on of a
remote data terminal to the common data lines.
FIG. 3 is a block diagram of the circuitry at each remote data
display unit RDS wherein the data and signalling lines have been
labeled to correspond to those shown in FIG. 2. When request button
250 is actuated a latch circuit 251 is energized which sends a
signal Si to the computer 11 which receives the signal and at the
same time a lamp 252 behind the "request" unit is energized by way
of a request contact circuit 252A. In addition, a second lamp 249,
labeled "wait," is energized by latch circuit 263 until the
computer sends a latch signal Ri to the terminal on its unique
line. The computer is programmed to transmit this signal if it is
not servicing another terminal or signal after it has completed
servicing the other terminal.
Prior to actuating the request signal, the operator will have
actuated one of data selection pushbuttons 200 in request panel
array 255 each of which has its own unique memory. Actuation of any
data selection pushbutton, produces a signal at interrupt pulse
circuit 256 which is applied as a "clear" signal to digital data
memory 257 which serves to cause the digital display 258 to exhibit
a series of zeros via BCD/D decoder 259 the output of which is
applied to the digital display lamps in display unit 258 by driver
circuits 260. The specific location of an actuated pushbutton in
panel array 255 is encoded by a request encoder 261. However, this
coded request data is not applied to the distribution bus for
transmission to the computer until the computer sends a signal Ri
on the stations unique line which serves to actuate latch circuit
263 causing "wait" lamp 249 to go out. The signal from latch
circuit 263 is applied to request encoder 261 to permit the request
information code (e.g., the column and row position of an actuated
data request unit 200) to be transmitted to computer 11.
Computer 11 receives the request information, formulates a response
and applies same to its output data lines. Since only the remote
data terminal receiving a signal Ri on its unique lines is latched
to the data lines, by way of gate 264, alarm gates 265, 266 and
267, only that station will display the information. The digital
information concerning the variables and their trend is stored in
digital data memory 257 which applies same to BCD/D decoder 259
which, in turn supplies signals to lamp drivers 260 for the digital
display 258. If the DA signal is present the background color will
be red and if the DG signal is present the background color will be
green to signify a safe or normal value.
In addition, red alarm lamps behind each data request unit may be
selectively energized to indicate an alarm condition. Thus the
location of the alarm lamp to be energized is received by alarm
gate 265 which, if signal Ri is present, passes these signals to an
alarm decoder 270, the output of which is passed by gate 271 upon
coincidence thereat of the alarm read signal AR from alarm read
gate 266. Hence the alarm location, the latch signal Ri and the
alarm read signal from the computer are necessary in order to
display an alarm at a specific data selection pushbutton 200.
Following the alarm gate 271 is an alarm memory 272 which serves to
supply signals to alarm lamp drivers 273, one for each data
selection pushbutton (if alarm conditions are to be given for all
data variables). One or more alarm lamps may be energized by the
computer to advise operators that it has detected an alarm
condition.
DATA SELECTION MATRIX
Data selection devices, such as 200 at each remote data station
RDS, are arrayed in horizontal rows and vertical columns, and the
specific position of a pushbutton is located by its respective row
conductor and respective column conductor (cartesan coordinates),
and each device has its own internal SCR memory for energizing,
when actuated, a respective row conductor and a respective column
conductor. However, it will be appreciated that the data selection
units need not be physically arrayed in horizontal rows and
columns. In FIG. 4, one row conductor (there being a row conductor
for each pushbutton row) is identified by the letter N, and a
column conductor (there being a column conductor for each column)
is identified by the letter M, so that the product M.times.N equals
the number of information variables displayable at a remote data
station. The energized row conductor and the energized column
conductor are connected to a row diode encoding matrix 300 and a
column diode encoding matrix 301, respectively, which actuate,
permutatively, row encoding relay switches 302 and column encoding
relay switches 303, respectively; the permutated closings (or
openings) of these switches identifying the particular pushbutton
which has been actuated by its cartesan coordinates. As described
later herein, this information is transmitted to the computer 11
where it is decoded and the information requested produced and
transmitted by computer 11 to the remote station. However, as noted
earlier this information is not transmitted to computer 11 until
computer 11 has signaled the remote station that it is free or able
to accommodate the request by transmission of latch signal Ri on
the station's unique line. Accordingly, the actuation of the
pushbutton at a selected position in the pushbutton array energizes
a memory circuit unique with respect to each pushbutton. In FIG. 4,
the memory includes a silicon controlled rectifier (SCR) 305 which
has its gate electrode G connected to the normally open pushbutton
switch element 200 PB through a dropping resistor R-15 to the 24
volt line. The cathode-anode circuit of SCR 305 is connected with a
"white" indicating lamp 306 across the 24 volt line and common.
Diagrammatically illustrated in association with the normally open
pushbutton switch 200 PB is a normally closed pushbutton switch 202
PB. As shown in FIG. 5, all of the data selection pushbuttons have
associated therewith a normally closed pushbutton switch 202 with
all of the normally open pushbutton switches being connected in
series.
In the circuit of FIG. 5, the direct current power supply,
diagrammatically illustrated as rectifier 220, supplies a positive
potential on line 221 and the output is regulated by regulating
transistor Q-7. Two output voltages are produced, the first, a
clean 24 volts taken from the emitter of regulating transistor Q-7,
and the second through dropping resistor R-15 to form the gate
voltage source for all of the SCR's 305.
Regulating transistor Q-7 has a Zener diode D-5 connected to the
base circuit thereof which serves to maintain the current through
transistor Q-7 constant. Also shown in FIG. 5 is a voltage divider
consisting of resistor R-5 and Zener diode D-7 having connected to
the intermediate point thereof capacitor C-3, Zener diode D-6, and
reverse current diode D-4. This circuit is connected to the base of
a switching transistor Q-8 which has resistor R-16 in the collector
circuit thereof, and the collector of transistor Q-8 is connected
directly to the base of transistor Q-7. It will be noted that the
switching transistor Q-8 is connected in shunt with Diode D-5.
As described thus far, the circuit shown in FIG. 5 operates as
follows: When a normally closed contact 202 is opened, the voltage
at the junction of Zener diode D-7 and resistor D-5 rises rapidly
to the 12 volts determined by the Zener in the voltage divider
circuit to produce a pulse (a few milliseconds wide). This pulse is
coupled through capacitor C-3, Zener diode D-6, and diode D-4 to
the base of transistor Q-8 which is normally nonconductive. This
pulse causes transistor Q-8 to conduct to thereby bypass regulating
Zener diode D-5 and place the base of series current regulating
transistor Q-7 at ground or common, and transistor Q-7 is thus
rendered open or nonconductive. Further, the 24 volts normally at
the emitter of transistor Q-5 goes to zero, and thus the 24 volt
supply to the arrays of SCR 305 (FIG. 4) is removed so that all
SCR's are returned to the blocking state to extinguish all white
lamps at all data selection and memory units. After this pulse has
passed, the 24 volts reappears, and the normally open contact (now
closed) of an actuated pushbutton supplies a signal to the gate
electrode G of its corresponding SCR 305 to thus energize the white
lamp 306 and supply a signal via isolating diode 308 to column
conductor M corresponding to a column in which the pushbutton
switch is located and a row conductor via diode 309 corresponding
to the row in which an actuated pushbutton switch is located.
As described earlier, the column conductors are connected to a
column diode encoding matrix 301, and the row conductors are
connected to a row diode encoding matrix 300 which, respectively,
encode the row and column information into a BCD code by way of the
reed relay switches 302 and 303. The respective matrixes drive the
reed relays, the contacts 302 and 303 of which are selectively or
permutatively closed according to the path formed by the diode
matrix. (There is no column matrix for the first column so the BCD
code for column one is 000; likewise, there is no row conductor for
row one so the BCD code for row one is 000.)
The data thus produced, being the encoded location of the actuated
pushbutton, is maintained by the continued energization or
actuation of SCR 305 even though the data locating the actuated
pushbutton is not transmitted until the computer 11 requests that
it be transmitted and after the computer has answered the request
and transmitted the requested data. As described earlier, this
memory action remains until another data selection pushbutton
switch is actuated elsewhere in the pushbutton array.
The signal produced at the base of transistor Q.sub.7 is used to
set flip-flop 280, which had been set in a first stable state by
the latch signal Ri from computer 11 during a previous
interrogation of the computer. When a signal at the set terminal S
of flip-flop 280 appears, the flip-flop changes states and a signal
is transmitted on line 281 to the data decoder (FIG. 6) and trend
data decoder (FIG. 7) to cause the display unit to exhibit the
character "0000" and to extinguish the trend color background
lamps.
When the latch signal Ri from computer 11 arrives on reset terminal
"R" of flip-flop 280, this circuit is reset to its initial state
and a signal is applied to OR gate 282 along with latch signal Ri
the output of which is supplied on line 283 to the buffer memory
(FIG. 6) to permit new incoming data to be fed to this memory.
With further reference to FIG. 4, it will be noted that each reed
relay 302 and 303 of the respective encoding matrices 300 and 301
is driven by a transistor Q.sub.2, there being one for each reed
relay. All such transistors receive operating potential from the 24
volt supply through a switch 315 which is actuated or energized by
the latch signal Ri. With respect to FIG. 3, this is constituted by
the Ri signal from latch circuit 263 to request encoder 261. Hence,
while transistors Q.sub.2 are permitatively conditioned for
energization by the diode encoding matrices 300 and 301, they are
not effectively energized until the Ri signal actuates switch
315.
DIGITAL DISPLAY CIRCUITRY
(DIGITS)
FIG. 6 is a block diagram of the circuit for decoding incoming data
and producing the display. Sixteen data lines 400 in groups of 4,
(units, (4) tens (4), hundred (4) and thousands (4) carry data on
common lines from the computer to the display terminals. The units
decoder and display system 401 will be described, tens 402, hundred
403 and thousands 404 systems being identical. It will be
understood that selected letters of the alphabet may be displayed
as well as numerals and other characters and it is obvious that the
display sequence will be thousands, hundred, tens and units.
It will be recalled that when a data selection unit was actuated a
signal had been applied on line 281 to set all display units to "0"
as well as turning off any background lights so the system is
conditioned for receiving the new data on data lines 400. Binary
bits applied to units system 401 are inverted by inverters 410 and
passed by OR gates 411 to buffer memory 412, which has been
conditioned by the latch signal Ri (FIG. 5) for transferring BCD
data bits (the code used in this system) to BCD to decimal
converter 413 which, in turn produces an output on one of its 10
output leads (0, 1, ....9). Whichever lead is energized, supplies a
signal to one of lamp drivers 414. For example if the "2" lead is
energized the lamp behind the character "2" to thus project the
character "2" on the display screen.
The tens 402, hundreds 403 and thousands 404 systems operate in a
similar fashion to thus display the transmitted character or
number.
TREND COLOR DISPLAY
FIG. 7 shows the circuit for trend color display. Again, it will be
recalled that the signal on line 281 which set the digit display
systems to "0000" also removed the background colors. This is done
by passing such signal through OR gate 420 in the red channel and
OR gate 421 in the green channel. Such signals are applied to the
reset terminals of flip-flops 422 and 423 respectively, which
remove signals from lamp drivers 424 and 425 respectively to
extinguish either the red or green lamps 426 and 427,
respectively.
One or the other of trend data signals DA (red) or DG (green) will
be transmitted from computer 11. If the DA signal is received, it
is applied as one logical input to AND gate 430 with the latch
signal Ri constituting a second logical input to this gate the
output of AND gate 430 is applied as the set input to flip-flop 422
which produces an output signal to be applied to lamp drivers 424
to cause the four red background lamps 426 to be energized.
Similarly, if the DG signal is received, it is applied to AND gate
431 with latch signal Ri to cause the four green background lamps
to be energized and provide a green background for the display.
DATA SELECTION ALARM CIRCUIT
Each data selection pushbutton is divided into two portions, the
white lamps described earlier being behind a portion labeled with
an indicator of the information available when it is actuated. The
second portion is used to provide an alarm condition signal from
the computer relative to the information available. Thus each data
selection unit is provided with a lamp behind a red shield. FIG. 8
is a block diagram illustrating decoding of such alarm information
from the computer to cause one red alarm at a desired location in
the data selection matrix to be energized.
As illustrated, alarm column data (SC.sub.1, SC.sub.2, SC.sub.4)
from the computer is applied to a binary to decimal decoder 501 and
alarm row data (SR.sub.2, SR.sub.2) is applied to binary to decimal
decoder 502. The system shown is for a 32 data selection pushbutton
array of four rows and eight columns, but may obviously be expanded
or decreased to accommodate as many variables for display and alarm
indication as is desired. The outputs of decoders 501 and 502 are
applied to an AND gate matrix 503, there being an AND gate at each
matrix cross-point and 32 AND gates for a 32 pushbutton array. The
coincidence of a signal from decoder 501 with a signal from decoder
502 at any matrix cross-point locates the pushbutton in the array
at which an alarm is to be posted. The output of each AND gate is
applied as the set input to flip-flop memory circuits 504, there
being one such flip-flop memory circuit 504 for each AND gate,
respectively. The output of flip-flop memory circuits 504 are
applied to lamp drivers 505 which, when actuated energize alarm
lamps 506 which respectively are located at the pushbutton in the
data selection array as described earlier.
In order to post an alarm, in addition to transmitting the location
of same, the computer 11 also transmits an alarm signal AR which is
applied as one input to AND gate 507 along with latch signal Ri.
The output signal from gate 507 is applied to decoders 501 and 502
and is necessary in order to permit decoders 501 and 502 to decode
information on the alarm data lines.
In order to clear a posted alarm, e.g., deenergize any of lamps 506
which have been energized, the computer 11 transmits an alarm clear
signal PR which signal is applied as one input to AND gate 508
along with latch signal Ri as the second input. The output of AND
gate 508 is applied as the reset input to all flip-flop memories
504 so as to deenergize all alarm lamps 506 simultaneously.
It will be appreciated that since the alarm signalling system is to
a certain extent separate from the digital display system described
earlier, the computer may be programmed to scan the unique lines to
each remote data display terminal and post one or more alarms to
call the operator's attention to this condition and take
appropriate corrective action.
While a specific embodiment of the invention has been described in
detail it will be appreciated that many variations thereof will
readily suggest themselves to those skilled in the art so the
invention is not limited to the specific embodiment disclosed but
includes those variations which come within the spirit and scope of
the claims appended hereto.
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