JPH0720104B2 - Signal transmission device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a signal transmission device for transmitting on / off signals from a plurality of detectors to a control device, and particularly to system automation of machines, ships, houses, etc. The present invention relates to a signal transmission device suitable for use.

[Conventional technology]

Conventionally, in an apparatus using this type of system, as shown in FIG. 5, ON / OFF output from each detector (for example, limit switch, reed switch, pressure switch, thermo switch, etc.) S _{1 to} Sn The signals are added in parallel to the control device 10 including a sequencer and the like via separate signal lines L _{1 to} Ln protected by conduits shown by broken lines.

[Problems to be solved by the invention]

However, in the above device, since each detection unit is connected in parallel to the control device 10 via a separate signal line, when the number of detectors increases, the number of signal lines correspondingly increases and the entire device. However, there is a problem that the cost becomes high and a considerable space is required for wiring the signal lines.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a signal transmission device capable of significantly reducing the number of signal lines and conduits and accurately transmitting the output of a detector.

[Means and Actions for Solving Problems] According to the present invention, in a signal transmission device that serially transmits on / off signals from a plurality of detectors to a communication device in response to a set signal output from the communication device. A limit switch unit is separately provided for each of the plurality of detectors, and a clock signal line and a set signal line from the communication device are commonly input to the plurality of limit switch units, respectively. Data signal lines are commonly connected and input to the communication device, and each of the limit switch units has a setting means for setting a different value for each of the plurality of detectors and an ON terminal of the detector. / OFF signal is input, and the set value set in the setting means is initially set in response to the input of the set signal. Down-counting means for performing a one-count counting operation on the initial set value one by one in accordance with the clock signal, and fetching an on / off signal from the detector applied to the input terminal when the count value becomes 0; Multivibrator means having a time constant circuit for completing the pulse output of the on / off signal from the detector taken in by the down counter means within a time period shorter than the cycle of the clock signal and outputting it to the data signal line. And a communication device having serial-parallel conversion means for converting ON / OFF signals of the plurality of detectors serially input via a data signal line into parallel data and sending the parallel data to the control device. ing.

In this invention, the pulse output of the ON / OFF signal from the detector taken in by the down counter means is completed within a time period shorter than the cycle of the clock signal and is output to the data signal line, whereby the data signal is outputted. It prevents the line from going to the same, eg, L level, regardless of the on / off state of each detector.

〔Example〕

An embodiment of the present invention will be described in detail with reference to the drawings of FIGS.

FIG. 1 shows an embodiment in which limit switches are used for the detectors S _{1 to} Sn that output ON / OFF signals.
The clock signal oscillated from the oscillator 12 of the communication device 11 is the frequency divider 13 and the serial-parallel converter 14 of the communication device 11.
Further, this clock signal is input to each limit switch unit U _{1 to} Un having limit switches S _{1 to} Sn and up / down counters D _{1 to} Dn, respectively.
The frequency divider 13 uses the clock signal CLOC oscillated from the oscillator 12.
Divide K and output the divided signal to each limit switch unit U _{1 to} Un as a set signal SET for synchronization.

Each of the limit switch units U _{1 to} Un is arranged at a predetermined device location, and based on the clock signal CLOCK and the set signal, the ON / OFF signals from the limit switches S _{1 to} Sn are set at different predetermined times. The signal is sampled at and output to the signal line 20. The signal SIGNAL of this signal line 20 is the data input of the serial _- parallel converter 14.
In addition to Ds, the serial _- parallel converter 14 converts the signal SIGNAL input from this data input Ds into a parallel signal corresponding to each limit switch unit, and outputs it from the output terminals A _{1 to} An to the control device 10. .

Next, the details of the limit switch units U _{1 to} Un will be described. Each of the limit switch units U _{1 to} Un has the same configuration as that of the limit switch unit U shown in FIG. 2, and an ON / OFF signal from each limit switch S is sent to each limit switch unit by the setting plug P. The time to output to the signal line 20, that is, the channel is set.

The up / down counter D operates as a down counter with the up / down control terminal U / D and the reset terminal grounded. When a high-level set signal SET for synchronization is input to the preset terminal PE of the up / down counter D, the binary number corresponding to each channel set by the setting plug P is a binary input terminal of the up / down counter D. The up / down counter D is initialized via P _{1 to} Pm. And up / down counter D
Starts counting down from the initial setting value at the rising edge of the clock signal CLOCK input from the oscillator 12 to the clock input terminal CK. The initial setting value is set to a different value for each limit switch unit U _{1 to} Un.

Assuming that the set value by the setting plug P is 5 and the limit switch S is in the ON state, the up / down counter D receives the high level set signal SET as shown in the time chart of FIG. When input to the preset terminal PE, the count value is preset to 5, and after that, the countdown starts at the rising edge of the clock signal CLOCK input to the clock input terminal CK. When the count value becomes zero, the signal indicating the on / off state of the limit switch S applied to the input terminals C and I at the rising of the clock signal CLOCK at this time, in this case, the limit switch S
The high level signal indicating the ON state of Output to. Of up / down counter D The signal output from is applied to the input terminal B of the multivibrator M.

By the way, of this up / down counter D When the output of the limit switch S is at high level, the signal output from is held at low level until the signal applied to the preset terminal PE becomes high level. Therefore When the pulse of is directly output to the signal line 20, the signal of the signal line 20 is output regardless of the ON / OFF state of the limit switch in the limit switch unit (for example, the setting value by the setting plug P is 6 or more) after that. All become low level. To solve this point, the next rise of the clock signal CLOCK, that is, the up / down counter of the next limit switch unit From the output signal to the up / down counter The low level signal from must be terminated.
Therefore, the pulse width of the output pulse of the multi-vibrator M is set to a cycle shorter than the oscillation cycle of the clock signal by the time constant of the external capacitor C and the resistance R of the multi-vibrator M. The pulse output of the switch unit U is completed. That is, when a low-level signal is applied to the input terminal B, the multivibrator M stays low for a period of time determined by the time constant of the resistor R of the capacitor C (see T2 in FIG. 3) from the fall of this low-level signal. The level signal is output from the output terminal.

Therefore, each limit switch unit U _{1 to} Un sends an ON / OFF signal from each limit switch S _{1 to} Sn at a different channel time when the period set signal SET rises as shown in FIG. It will be sent to 20.
The ON / OFF signal sent to the signal line 20 becomes a serial signal time-divided in each channel time, and is input to the data input Ds of the serial-parallel converter 11 of the communication device 11.

As described above, the serial-parallel converter 11 converts this serial signal into a parallel signal corresponding to the ON / OFF signals of the limit switch units U _{1 to} Un, and outputs the control signals from the n output terminals A _{1 to} An. Output to 10.

Therefore, the ON / OFF signals output from the limit switch units U _{1 to} Un are transmitted to the control device 10 via the single signal line 20.

〔The invention's effect〕

As described above, according to the present invention, the pulse output of the ON / OFF signal from the detector taken in by the down counter means is completed within a time shorter than the cycle of the clock signal, and the data signal line is completed. By providing the multivibrator means having a time constant circuit for outputting, it is possible to prevent the data signal line from being at the same L level, for example, regardless of the ON / OFF state of each detector, thereby ensuring accurate data error-free. It is designed so that serial data transmission can be performed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention, FIG. 2 is an example of a configuration diagram of a limit switch unit of the present invention, and FIG.
FIG. 2 is a diagram showing a time chart when the count value of the up / down counter is set to 5, FIG. 4 is a diagram showing an example of the time chart of FIG. 1, and FIG. 5 is a diagram showing a conventional embodiment. Is. 10 ... Control device, 11 ... Communication device, 20 ... Signal line, U,
U _{1 to} Un …… Limit switch unit, D, D _{1 to} Dn ……
Up / down counter, P ... Setting plug, S, S ₁ ~
Sn ... Limit switch, M ... Multivibrator.

Claims (1)

[Claims] 1. A signal transmission device for serially transmitting ON / OFF signals from a plurality of detectors to a communication device in response to a set signal output from the communication device, wherein a limit switch unit is provided for each of the plurality of detectors. The clock signal line and the set signal line from the communication device are commonly input to the plurality of limit switch units, and the data signal lines from the plurality of limit switch units are commonly connected to the plurality of limit switch units. The limit switch unit is configured to set different values for each of the plurality of detectors, and an ON / OFF signal of the detector is input to an input terminal of the limit switch unit. In response to an input, the setting value set in the setting means is initially set, and this initial setting value is used as the clock signal. Therefore, the down-counting operation is performed one by one, and when the count value becomes 0, down-counter means for taking in the ON / OFF signal from the detector applied to the input terminal, and the down-counter means taken in by the down-counter means Multi-vibrator means having a time constant circuit that completes pulse output of the on / off signal from the detector within a time period shorter than the cycle of the clock signal and outputs to the data signal line. The apparatus is characterized by having serial-parallel conversion means for converting ON / OFF signals of the plurality of detectors serially input via a data signal line into parallel data and sending the parallel data to the control device. Signal transmission equipment.