Note: Descriptions are shown in the official language in which they were submitted.
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BRIEF DESCRIPTION OF THE PRIOR ART
AND SUMMARY OF THE I~VENTIO~
The invention relates to an apparatus for monitoring
a remote data line utilizing conventional telephone circuits
for coupling that remote line to a telephone line for mor.itor-
ing, testing or performing diagnostics~
Telephone lines are now widely employed for trans-
mitting data, and particularly for transmitting data from a
remote terminal to a central computer location where the com-
puter receives and manipulates the data to produce records orthe like. In order to make most efficient use of expensive
telephone lines, it is conventional to utilize data multiplex-
ers, mini computers and other similar electronic devices to
receive information on each of a plurality of ~ines from re-
mote terminals and to transmit that information on a singletelephone line to a computer which may be t~ousands of miles
away.
One problem which arises with such multiplexing, how-
ever, is that it is not normally possible for computer person-
nel at the central location to directly monitor the remotedata lines to determine which of the lines is causing a prob-
lem and to accurately diagnose the problem. All the computer
personnel can monitor is the information coming in from the
multiplexer on a single line and usually this is insufficient
to determine which of the several lines coming into the multi-
plexer is malfunctioning. Often t~le multiplexer location is
not staffed by human personnel at all times. Accordingly, when
this is the case, the only practical way to actually diagnose
the.problem is to send someone to the multiplexer to actually
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monitor each of its input lines and transmit that information
to the central computer siteO ~ot only does this often take
several hours during which the system is disrupted, but is, of
course, expensive in requiring payment of overtime, etc.
The present invention relates to a simple, inexpen-
sive and reliable circuit which can be connected to the data
lines coming into the multiplexer at the remote location where
those data lines are multiplexed or the information otherwise
concentrated for transmittal to the central location. The
circuitry has associated with it a unique telephone number
which, when dialed by someone at the central facility or other-
wise, connects the data monitor to the central facility via the
telephone lines. Each of the data lines is associated with a
unique coded number so that, when that number is entered into
the interrogating telephone by a touch-tone pad~ a dial or the
like, the data monitor decodes the signal and operates a relay
associated with the identified line to couple that line to an
audio bussO The information on the audio buss is then applied
to the telephone line and transmitted back to the remote sta-
tion where it can be monitored and any problem diagnosed. Eachof the data lines coming into the data monitor can be quickly
and simply checked in this fashion.
In the embodiment of the invention described in de-
tail below, the circuitry preferably includes a local speaker
at the data monitor and a telephone touch-tone pad or the like
for permitting the data lines at the remote terminal to also
be monitored at the local site. The circuitry can couple to
either the transmit or receive side of the line.
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Many other objects and purposes of the invention will
become clear from the following detailed description of the
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows a block diagram of the unique data
monitor of this invention.
Figures 2 and 2a when placed side-by-side show a de-
tailed schematic of portions of the control logic, the audio
amplifer for the local speaker and the input circu~try.
Figure 3 shows a detailed schematic of circuitry for
resetting the data monitor in the event of a power failure.
Figure 4 shows a detailed schematic of the tone de-
coder.
Figures 5 and 5a when placed side-by-side show a de-
tailed schematic of the control logic.
Figure 6 shows a detailed schematic of one set of
relay drivers.
Figure 7 shows a detailed schematic of circuitry for
preventing more than one of the lines from being coupled to
the audio buss at one time, this figure is shown on the sheet
illustrating Fig. 3.
Figure 8 shows a detailed schematic of the display
driver circuitry.
DETAILED DESCRIPTION OF THE DRAWINGS
Reference is now made to Figure 1 which illustrates
in block diagram the unique data monitor of this invention.
As indicated briefly above, the data monitor is conventionally
connected to a telephone line 20 such that when the number
identifying the data monitor is manually dialed or entered into
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a touch-tone pad or otherwise entered into the telephone grid,
the remote telephone is coupled to line 20 and conventional
telephone signals are received in the data monitor and routed
by the conventional data access and acquisition terminal 22
Terminal 22 is coupled to another conventional element 24
which functions to cause the line to be answered~ i.e., the
data monitor coupled to line 20, when an appropriate signal
is received on line 26 from the control circuit 28 discussed
in detail below. Both terminal 22 and circuit 24 are conven-
tional devices and are not illustrated nor discussed in de-
tail below.
Once the line has been answeredO the telephone at
the remote end of line 20 can enter a coded signal identifying
one of a plurality of data lines, generally indicated as 30,
which is to be monitored. Data lines 30 are also connected,
as described above, to an information concentrator such as a
multiplexer, or the like. The data monitor then responds by
coupling that identified line to an audio buss 32 so that,
after amplification and filtering in a conventional filter
and amplifier as circuit 33, the information on the identified
remote data line is directly coupled to phone lines 20 and can
be heard at the remote telephone at the other end of phone
line 20.
The coded signals identifying the desired line may
be in the form of combinations of audio tones conventional~y
known as touch tones. These tones are decoded by a circuitry
34 which identifies the desired line to be interrogated an~
applies a signal to the control circuitry 28 which in turn
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applies a signal to one of a plurality of relay boards with
boards 40, 42 and 44 illustrated in the block diagram of Fig-
ure 1. In the particular arrangement which is described in
detail it is contemplated that 10 relay boards will be employ-
ed, permitting the data monitor to monitor both the receiveand transmit sides of 49 remote date data lines indicated gen-
erally as 30 Each relay board includes a plurality of relays
each associated with one side of a data line and that relay is
activated by the signal from control logic 28 to close switches
to connect the associated data line to the audio buss 32.
As indicated briefly above, the data monitor also
preferably includes a conventional touch-tone pad 50 and a
local speaker 52 which is connected to audio buss 32 via power
amplifier 54 for permitting a code identifying a data line to
be entered at the data monitor location and the information on
that line to be actually heard at the local station. The cir-
cuitry also preferably includes an output jack generally indi-
cated at 56 for applying the signals on the audio buss 32-to
a meter or other diagnostic tool at the data monitor itself.
Thus, the data monitor can be used not only for remote monitor-
ing of the data lines but monitoring at the multiplexer itself.
Reference is now made to Figures 2 and 2a which il-
lustrate a detailed schematic of portions of the data monitor
circuitry including portions of the control logic 28, the power
amplifier 54 and the filter and amplifier circuit 33~ The con-
ventional telephone grid now in use provides a ring signal to
a telephone identified by a dialed number which periodically
grounds the incoming telephone line for a short time. In the
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data monitor of this invention, this signal is applied to the
data monitor on line 60 and is coupled to the base of normally
saturated transistor 62. The collector of transistor 62 is
connected via diode 64 and resistor 66 to a capacitor 68 which
5 begins to charge when line 60 is grounded shifting transistor
62 to its non-conductive condition. After a number of rings,
for example, three groundings of line 60, capacitor 68 is
charged to a voltage sufficient to trigger conventional timer
70. By requiring at least three rings, some measure of protec-
10 tion is provided against inadvertent operation of the circuit-
ry by a wrong number or noise on line 60.
Timer 70 responds by shifting its output condition
from a high to a low levelO causing transistor 72 to shift
from its normal conductive condition to a non-conductive con-
15 dition which causes the power supply to be disconnected fromthe local touch-tone pad 50~ This prevents any interrogation
with the local touch-tone pad while remote monitoring is con-
tinuing. The shifting of transistor 72 also causes transistor
74 to shift to a conductive condition, grounding line 76 which
20 is connected to the automatic answering circuit 24 so that
circuit 24 now answers the phone, coupling phone line 20 to
line 80 within the data monitor.
The collector of transistor 72 is connected to ca-
pacitor 68 via resistor 82 so that when transistor 72 shifts
25 from its conductive to its non-conductive condition capacitor
68 is kept charged by a current path through resistors 82 and
84. There are now two ways in which line 80 can be disconnect-
ed from line 20.
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Line 85 is connected to the counters within the con-
trol logic circuit 28 so that a voltage is applied to line 85
to keep transistor 86 saturated so long as the monitoring con-
tinues. So long as line 85 remains at a high voltage, tran-
sistor 86 remains conductive, preventing capacitor 88 fromcharging. Capacitor 88 is connected as illustrated to the in-
put to timer 90, while the output of timer 90 is coupled to
capacitor 68. When line 85 shifts to a low voltage causing
transistor 86 to shift to its non-conductive condition, capac-
itor 88 begins to charge through resistor 91. Line 85 is con-
nected to the output of a counter in the control logic illus-
trated in detail in Figure 5 and line 85 shifts to a low out-
put when the counter in the control logic is reset in response
to receipt of a reset signal as explained further below.
The values of capacitor 88 and resistor 91 are chosen
such that it takes about 40 seconds for capacitor 88 to charge
to a voltage sufficient to trigger conventional timer circuit
90, which then shifts to its low output condition permitting
capacitor 68 to discharge via diode 920 When capacitor 68 has
discharged below the level necessary to keep timer circuit 70
in its low output condition~ timer circuit 70 shifts that out-
put, causing transistor 72 to resume its normal conductive con-
dition which grounds the base to transistor 74. Transistor
74 then becomes non-conductive causing automatic answer cir-
cuit 24 to disconnect the data monitor from phone line 20.Capacitor 88 now discharges via resistor 94 and diode 97. Thus
the data mon.itor will hang up if a digit signal is now receiv-
ed.
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A second timer having a longer period than timer 90
is also provided as an additional guarantee that the data mon-
itor will be correctly disconnected from the phone line even
if the reset signal is not received. Capacitor 96 is connect-
ed to a 12-volt source via resistor 84 and resistor 98 so that
capacitor 96 begins to charge ~len transistor 72 shifts away
from its normal non-conductive condition. Capacitor 96 and
resistors 98 and 84 are chosen such that capacitor 96 takes
about 10 minutes to reach a voltage sufficient to trigger timer
100 which then shifts to its low output condition permitting
capacitor 68 to discharge via diode 102. If, during the
charging of capacitOr 96, a reset signal is received, that sig-
nal is applied to the base of transistor 104 on line 106 caus-
ing that transistor to shift to its conductive condition which
discharges capacitor 96. Thus, if a reset signal is not re-
ceived within 10 minutes following the last receipt, the cir-
cuitry assumes something is wrong and automatically disconnects
the data monitor from phone line 20.
Once the data monitor has been coupled to phone line
20 by the automatic answering circuit 24, a coded signal can
then be transmitted from the remote location to the data mon-
itor identifying one line to be coupled to the telephone line
for monitoring. This coded information typically is in the
form of combinations of tones received on line 80 and applied
to a differential amplifier 110 in Figure 2. During data
transmission on the phone line from the data monitor, differ-
ential amplifier 110 removes outgoing data from incoming touch
tone control signals. The output of differential amplifier
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110 on line 112 is applied to the tone decoder input line 114
illustrated in Figure 4.
A plurality of conventional tone decoders 116, 118,
120, 122, 124, 126 and 128 are connected to line 114 and pro-
vide outputs as indicated when a tone of the associated fre-
quency as shown in Figure 5 is received. The outputs of tone
decoders 116, 118, 120, 122, 124, 126 and 128 are applied to
conventional gates 130, 132, 134, 136, 138, 140, 141, 142, 144,
146, 148 and 150 to provide 10 outputs each corresponding to
one of the conventional digits, an 11th output corresponding
to an * which is one of the conventional tone keys on a tele-
phone and a 12th output corresponding to the symbol # which
represents another conventional tone key on a touch-tone tele-
phone. Thus, each incoming combination of tones is decoded to
provide an output on a line indicating the associated digit or
symbol. The outputs of gates 130, 132, 134, 136, 138, 140,
141, 142, 144 and 146 are applied to gates 152, 154 and 156
with the outputs of those gates applied to an OR circuit com-
prising diodes 160, 162 and 164. The output of this OR circuit
is in turn inverted by gate 166 to provide an output on line
168 each time that a coded signal is received associated with
a digit. This output is called the strobe output and is util-
ized to decode two or more place digits as will be explained
below.
The outputs of gates 130, 132, 134, 136, 138, 140,
141, 142, 144, 146, 148 and 150 are applied to the inputs to
the control logic 28 which is illustrated in Figure 5. Refer-
ring to Figure 5, strobe line 168 is applied to a counter com-
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prising flip-flops 170 and 172 via a pair of transistors 174
and 1i6. The counter comprising flip-flops 170 and 172 indi-
cates whether a digit which is being received is the first
digit in a string, the second digit in a string, etcO When
the first digit is received, a signal is produced on line 168
which shifts the output condition of the counter comprising
flip-flops 170 and 172~ That condition is decoded by gate 230
to produce a signal which is applied to each of gates 232, 234,
236, 238, and 240 to enable each of these gates 232, 234, 236,
238, and 240 which are each connected to one of the digit out-
puts of the tone decoder circuitry of Figure 4. Gates 232,
234, 236, 238 and 240 further each has its outputs connected
to a corresponding flip-flop which is comprised conventionally
of a pair of gates. Flip-flop 260 is associated with gate 232,
flip-flop 262 with gate 234, flip~flop 264 with gate 236, flip-
flop 268 with gate 2380 flip~flop 270 with gate 240~ Each of
these flip-flops shifts its output condition whenever the as-
sociated gate shifts its output condition as discussed above.
The outputs of flip-flops 2009202,204, 206t 208, 210, 212, 214,
216 and 218 are each connected to one input line on the relay
driver's circuit of Figure 6, and each of these lines identi-
fies one line associated with one driver. Flip-flops 200, 202,
204, 206, 208, 210, 212, 214, 216 and 218 further are each
connected to a reset line 220 which shifts these flip-flops
back to their initial condition when a signal is produced on
that reset line in response to a reset signal indicating that
monitoring of a chosen line has ended. The reset signal is
decoded by gate 148 in Figure 4 and the output of that gate
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applied to transistor 224 to shift that transistor from it-~
non-conductive to its conductive condition, grounding the re-
set inputs of flip-flops 170 and 172 to reset the counter to
zero.
S Receipt of one digit shifts counter comprising flip-
flops 170 and 172 from one output condition to the other. Re-
ceipt of a second strobe signal indicating a second digit has
arrived shifts the output of the counter further so that gate
230 no longer provides an enabling signal but rather the out-
puts of flip-flops 170 and 172 as decoded by gate ~4 provides
an enabling signal for gates 178, 180, 182, 184, 186, 188, 190,
192, 194 and 196 further identifying the line to be monitored.
As indicated above, ~each of the data lines 30 has a
receive portion and a transmit portion and either the receive
portion or the transmit portion can be monitored. Receipt of
a # on line 114 in Figure 4 causes gate 150 to produce a sig-
nal which shifts the output condition of flip-flop 250 which
is also reset by transistor 224.
The outputs of gates 232, 234, 236, 238 and 240 are
applied to respectively associated flip-flops 260, 262, 264,
268 and 270, The outputs of flip-flops 260, 262, 264, 268 and
270 are applied to five sets of gates each comprising two sep-
arate gates. One of the gates is enabled by one output of
flip-flop 250, while the other gate is enabled by the other
output. Thus, gate 271 will provide an enabling signal on
line 272 when flip-flop 250 is shifted to a condition indicat-
ing that the transmission side of the line is to be monitored.
Conversely gate 274 will provide an output on line 276 to en-
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able a relay driver as discussed below, when the receive por-
tion of a certain line is to be monitored. Gates 280 and 282
are associated with flip-flop 26a while gates 284 and 286 are
associated with flip-flop 264, gates 288 and 290 are associat-
ed with flip-flop 268 and gates 292 and 294 are associated with
flip-flop 270.
Reference is now made to Figure 6 which illustrates
one of the relay driver circuits for the data monitor. In the
particular embodiment which is described in this application,
ten such circuits are required. Each of the outputs of flip-
flops 200, 202, 204, 206, 208, 210, 212, 214, 216 and 218 in
Figure 5~ is connected to one of the inputs as indicated in
Figure 7 in each of the ten relay driver circuits. Further,
each of the outputs of gates 271, 274, 280, 282, 284, 286, 288,
290, 292 and 294 are connected to each-of the gates 300, 302,
304, 306, 308, 310, 312, 314, 316 and 318 in one of the ten
relay driver circuits. In this fashion one of the lines in one
of the relay driver circuits - transmit or receive - is identi-
fied. Each of gates 300, 302, 304, 306, 308, 310, 312, 314,
316 and 318 has associated ~ith it a conventional relay which
is activated to close two controlled switches to couple a sel-
ected line to the audio buss lines 320 and 322. Reed relay
324 is associated with gate 300 and when gate 300 is enabled
current flows through relay coil 324, closing controlled
switches 326 and 328 to connect one data line, either the
transmit or receive portion, to the audio buss lines 320 and
322. Similarly, relays 330, 332, 334, 336, 338, 340, 342,
344, and 346 are respectively associated with gates 302, 304,
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306, 308, 310, 312, 314, 316 and 318.
It is desirable to prevent two lines from ever being
connected at the same time to an audio buss since the result
will be confusion at the best and problems in the lines at the
worst. Accordingly, the circuitry of Figure 7 is provided and
is connected to each of the respective relays of the relay
boards such that either controlled transistor 3S0 or 3S2 shifts
from its normally non-conductive condition to a conductive con-
dition cutting off the supply of voltage to the relay drivers
and in effect preventing interrogation of any of the remote
lines, whenever two relays are activated~
Referring again to Figure 2, the signals on audio
buss lines 320 and 322 are connected to an isolation transfor-
mer 360 in filter and amplifier circuit 34. The output of
isolation transformer 360 is applied to a filter circuit 362
which removes noise and the signals are then amp~ified in a
conventional amplifier 364. The output of amplifier 364 is
applied to the output telephone line via line 366. While an
output signal is being produced, the input information is also
fed to the negative input of operational amplifier 110 to pre-
vent interference of outgoing and incoming informationO
Reference is now made to Figure 3 which illustrates
a simple circuit for making sure that the circuitry is reset
in the event of a power failure~ If power should fail, tran-
sistor 400 shifts its output condition providing a reset sig-
nal.
Reference is now made to Figure 8 which illustrates
the output circuitry for the local display 35 indicating a
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chosen data lineO This display 35 is particularly useful where
the data monitor is being used at the remote station for in-
terrogation. The outputs of flip-flops 200, 202, 204, 206,
208, 210, 212, 214, 216 and 218 are applied via conventional
inverters to a decimal to binary converter 402 and the output
of binary converter 402 applied to a further converter 404
which provides the seven outputs used to conventionally oper-
ate an LED display 405 of one digit~ Similarly, the outputs
of gates 271, 274, 280, 282, 284, 286, 288, 290, 292 and 294
are applied to a further decimal to binary converter 406 and
the output of that converter decoded by converter 408 to drive
a second LED display 410.
Many changes in modifications in the above-described
embodiments of the invention can, of course, be carried out
without departing from the scope thereofO Accordingly, that
scope is intended to be limited only by the scope of the ap-
pended claimsO
