JPS61163456A - Signal input processing unit - Google Patents

Abstract

PURPOSE:To attain inexpensive input processing with high reliability by providing a cut-off circuit of a signal line at the pre-stage of a potential converting circuit of an input signal and providing a storage circuit holding tentatively an output signal of a potential converting circuit. CONSTITUTION:The cut-off circuit 17 consists of a photocoupler 13 provided with an output transistor (TR)13a and a light emitting diode 13b, of a resistor 14 and a low voltage power supply 10, and the anode of the diode 13b is connected to the power supply 10 and the cathode is connected to an output port 12. Further, a storage circuit 37 consists of a delay circuit 35 and a data latch circuit 36, and the circuit 35 gives an output signal 12a of the output port 12 to the input. In the input processing of an external signal, when the circuit 17 is not operated, the output of the circuit 16 is outputted as it is in addition to the output of the potential converting circuit 16 and the output of the circuit 16 just before the cut-off operation is held by the circuit 37 when the circuit 17 is operated. Thus, the inexpensive input processing with high reliability is attained in such a way that plural computer circuits are used in common by using the same external signal and one signal input processing circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a signal input processing device for inputting external signals to a computer control device.

[Conventional technology]

FIG. 3 shows a conventional general computer circuit and an external signal input circuit as shown in, for example, Japanese Patent Application Laid-Open No. 59-53377. is CPU 2, memory 3. It consists of an input boat 4 and an output boat 5.

B is an external signal input circuit, and the positive terminal of the external high voltage power supply T is a contact point of a toggle switch, push button, relay, etc.
Current limiting resistor 8. a light emitting diode 9b of the photocoupler 9;
The photocoupler 13 is connected to the negative electrode of the external high voltage power supply 7 via the output transistor 13m.

The photocoupler 9 forms the main part of the potential conversion circuit 16, and has a light emitting diode 9bK output transistor 9& facing it, its emitter is grounded, and its collector is connected to a pull-up resistor 11t to provide a low voltage for computer circuits. It is connected to a power source 10. The output of this potential conversion circuit 16 is connected to the input port 4.

The photocoupler 13 is the main part of the cutoff circuit 17, and a light emitting diode 13b is provided opposite the output transistor 13&, and its anode is a resistor 14t.
It is connected to a low voltage power supply 10 through the terminal, and its cathode is connected to an output port 12.

Next, one operation will be explained. When the contact 6 is off, the photodiode 9bK current of the photocoupler 9 does not flow and the output transistor 9a is off, so the input signal to the input port 4 is passed through the pull-up resistor 11 to the low voltage power supply 10. It is pulled up to a voltage and becomes "H" level.

Also, if contact 6 is on, external high voltage power supply 7
Since current is supplied to the light emitting diode 9b of the photocoupler 9 via the stain flow control resistor 8, the output transistor 9
1 is turned on, and the input signal to input port 4 becomes rLJ level.

That is, the current limiting resistor 8. Hotokabura 9. Pull-up resistor 11. The low voltage power supply 10 is connected to the external high voltage power supply 7 and functions as a potential conversion circuit 16 that converts the signal of the contact 6 into a low voltage signal.

Therefore, the state of the contact point 6 is inputted to the input port 4 via this potential conversion circuit 16, and is input to the CPU 2.

Computer circuits generally operate on low voltage power supplies,
In addition, such an external signal input circuit B is generally configured at a high voltage level in consideration of the contact reliability of the contacts 6 and noise immunity in signal transmission, and a photocoupler or a photocoupler is used for the signal interface. Potential conversion elements and devices such as relays are used.

Furthermore, 1-signal transmission is designed to operate safely against failures such as wire breakage and poor contact, and in particular, for safety-related signals, it is important to configure the circuit so that the input signal is at the presence/absence level when the contact is turned on. Common.

Therefore, if the potential conversion circuit 16 fails on the on side, it is fatal, and as a measure to improve reliability, an on-failure check of the potential conversion circuit 16 as shown in FIG. 3 is performed.

Next, the operation of checking the on-failure of the position substitution circuit 16 will be explained using the flowchart shown in FIG. FIG. 4 is a flowchart showing the flow of the program stored in the memory 3. Step 21 is an initial setting program that sets the data necessary to operate the program and initializes the output of each output port to i"L'. , Step 22 is a processing program for starting a check to apply @''HH level to the output port 12, Step 23 is a program for inputting the signal of the contact 6 via the input port 4 and determining whether the state of the contact is on or off. Step 24 is a check completion processing program that outputs @L# level to output port 12. Step 25 inputs the signal of contact 6, performs predetermined processing using this signal, and outputs the result to output port 5. This is a processor program that outputs data to an external output device (not shown) via the computer.

Step 26 is an abnormality detection processing program that outputs the fact that the contact 60 input circuit is out of order to an external alarm device (not shown) via the output port 5, 2T is a check completion processing program similar to step 24, Step 28 is a program called process B that executes general calculations etc. that are not related to the signals of the contacts 6 other than the above-mentioned processor.

First, when the low voltage power supply 10 for the computer circuit and the external high voltage power supply 7 are turned on, the program shown in Fig. 4 is started, the initial setting program in step 21 is executed, and the output port 12 is reset to @L'. Therefore, the cutoff circuit 1
Since the photocoupler 13 of T is turned on, the external high voltage power supply 7 ←
) side bus bar is connected, then step 22
In the check start process, the output of output port 12 becomes '''H#
At H# level, no current flows through the light emitting diode 13b of the photocube 213, so the output transistor 13a is turned off. As a result, the one side bus of the external signal input circuit B is disconnected.

Next, in step 23, the state of the contact 6 is determined, and the information on the contact 6 is input to the CPU 2 via the photocoupler 9 and the input port 4, but the one side bus of the external signal input circuit B is disconnected. Therefore, regardless of whether the contact 60 is on or off, the output transistor 9a of the photocoupler 9 is in the off state, and "H level" is output to the input port 4.
Contact 6 is determined to be in the off state, and the next step 24
Proceed to.

In step 24, the output port 12 becomes @L# level, the photocoupler 13 is turned on, the one side bus of the external signal input circuit B is connected to the output transistor 13&, and the signal at the contact 6 is transferred to the photocoupler 9 and the input port 4. K so that a signal can be input via.

Thereafter, in step 25, signal acquisition processing of the regular contact 6 is performed, followed by other general arithmetic processing in step 28, and the process returns to the first step 22, and the series of programs is repeatedly executed.

However, if the photocoupler 9 fails to turn on, the contact 6 is determined to be on in step 23, so the process proceeds to step 26, where an abnormality is detected and an alarm signal is output to the outside, and the check completion process is executed in the next step 27. be done. In this case, step 25, which is the input process for the contact 6, is skipped, and another process, step 28tl-, is executed.

In this way, before inputting the contact signal, the potential conversion circuit 1
A possible method is to create a state equivalent to the state where the contact is open in the previous stage of step 6, and check that the input signal indicates that the contact is open, thereby increasing the reliability of the input contact signal.

By the way, recent large-scale control devices are designed to efficiently execute complex processing and shorten processing time by having multiple computer circuits perform separate arithmetic processing in full parallel. When signals are used in each computer circuit, some signal processing circuits such as potential conversion are shared in order to save money.

Therefore, this shared signal processing circuit is required to be highly reliable. Therefore, it is possible to adopt measures to improve reliability as described above.

[Problem that the invention seeks to solve]

However, since conventional signal input processing circuits have the above configuration, when the output is jointly used by multiple computer circuits, when one computer circuit checks for a failure in the signal input processing circuit, the other computer circuit If the input signal is unconditionally turned off, there is a problem in that the correct signal cannot be received.

In order to increase the reliability of signal input processing circuits, it is necessary to provide separate signal input processing circuits for each computer circuit even for the same signal, and take measures to improve the reliability of input signals by methods such as mutual signal comparison. There were some problems, such as having no choice but to do so.

This invention was made to solve this problem. Even when one computer circuit checks for a failure in the signal input processing circuit, the other circuit can input the correct signal, and moreover, only one computer circuit can input the correct signal for the same signal. It is an object of the present invention to provide an inexpensive and highly reliable signal input processing device that can share a signal input processing circuit.

[Means for solving problems]

The signal input processing device according to the present invention includes a signal line cutoff circuit upstream of a potential conversion circuit for input signals, and a storage circuit that temporarily holds an output signal of the potential conversion circuit.

[For production]

In this invention, when a cut-off command is output to the cut-off circuit, the memory circuit continues to hold the output of the potential conversion circuit immediately before cut-off, and when a cut-off command is not output, the memory circuit outputs the output sound of the potential conversion circuit as is. From this output, a correct input signal is obtained that is not affected by the change in the output of the potential conversion circuit when the signal line is cut off.

〔Example〕

Embodiments of the signal input processing device of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of one embodiment. In FIG. 1, parts that are the same as those in FIG. 3 are given the same reference numerals and their explanations will be omitted, and the parts that are different from those in FIG. 3 will be mainly described.

As is clear from comparing Figure 1 with Figure 3,
In the figure, computer circuit A, external signal input circuit B
is the same as in FIG. 3, computer circuit 30. A memory circuit 37 is added, and the computer circuit 30 includes a CPU 31 . Memory 32° input port 33. It consists of an output boat 34.

Furthermore, the memory circuit 37 includes a delay circuit 35 and a data latch circuit 36. The delay circuit 35 consists of 35 NOR gates, a resistor 35B, and a capacitor 35C.
The output signal 12m of the output port 12 is connected to the input.

Furthermore, when the gate input signal G is at the 'H'' level, the data latch circuit 36 outputs the level of the input signal of the input input signal Q.
That “1”! When the gate power G is at the "L" level, it continues to hold the level of the data power when it changes from @H' to "L", and the output of the external signal input circuit B is at the data power level. , the output 351 of the delay circuit 35 is input to the gate input G, and the output Q is input to the input port 33 of the computer circuit 30.
It is similar to the figure.

Next, the operation of this embodiment will be explained. First, as described above, in the computer circuit 1, in order to cut off the H side bus of the signal input circuit B in step 22, according to the flowchart shown in FIG.
A command to turn off the photocoupler 13 is output, and step 24
Since the photocoupler 130 ON command is output as a return command, the waveform of the output 12& of the output port 12 becomes a pulse-like waveform as shown in FIG. 2 (4).

On the other hand, the operation of the output transistor 13& of the photocoupler 13 turns on as shown in FIG. 2 (03) with a certain delay based on the time constant of the resistor 35B and capacitor 35C.

The off waveform 13c is particularly K. Therefore, this OFF period is not related to the operation of the contact 6, and since the hot cube 79 is OFF, the output of the external signal input processing circuit B is "H".
If the level is 2, the signal at contact 6 is not transmitted to CPU circuit 31 and memory circuit 37.

In addition, in the delay circuit 35 in the memory circuit 37, the output 12a of the output port 12 is connected to one input of the NOR gate 35 and to the other input via the resistor 35B, and at the same time is connected to the Ov line via the capacitor 35C. (ground), the input signal 35b has a time constant determined by the resistor 35B and the capacitor 35C, and has the waveform shown in FIG. 2(e).
The output 35m of No. 5 has a waveform of ) in Fig. 2.

As a result, during the period when the photocoupler 13 is off, the output 35a of the delay circuit 35 is not at @L# level, and the photocoupler 9 of the cutoff circuit 17 immediately before the photocoupler 13 turns off.
The output of the photocoupler 9 is held in the data latch circuit 36, and after the photocoupler 13 is turned on, the output 35& of the busy delay circuit 35 becomes @H'' level, so the output of the photocoupler 9 is again connected to the output terminal Q of the data latch circuit 36. The signal is input to the input port 33 of the computer circuit 3o so that the signal is output as is.

That is, during the checking period of the external signal input circuit B by the computer circuit 3o, the output of the external signal input circuit B immediately before that is held in the data latch circuit 36, and after the check is completed, the output of the external signal input circuit B is again transmitted to the other computer circuits. This allows one computer circuit to check an external signal input circuit to prevent erroneous detection of an input signal from another computer circuit.

Note that the delay time of the delay circuit 35 needs to be set longer than the operating time of the cutoff circuit 17, that is, the operating time of the photocoupler 13, and the capacitor 35C and resistor 35B may be appropriately selected.

In addition, in the above embodiment, the means for cutting off the front stage of the potential conversion section of one contact signal input circuit was explained, but the common bus of a plurality of contact signal input circuits is cut off, and the cutoff is performed during this cutoff period. A plurality of input circuits may be sequentially checked.

〔Effect of the invention〕

As described above, according to the present invention, in addition to the output of the potential conversion circuit, when the cutoff means is not operating, the output of the potential conversion circuit is output as is, and when the cutoff means is operating, the output of the potential conversion circuit is output as is, and when the cutoff means is operated, the output of the potential conversion circuit is output as is. Since the output of the potential conversion circuit is held in the storage means, multiple computer circuits can share the same external signal via one signal input processing circuit, and this signal input processing circuit can also be used to store signals from other computer circuits. Since the circuit is designed so that the operation can be confirmed by turning it on and off without affecting the input, an inexpensive and highly reliable signal input circuit can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the signal input processing device of the present invention, FIG. 2 is a time chart for explaining the operation of the above signal input processing device, and FIG. 3 is a block diagram of a conventional signal input processing device. 4 is a flowchart of a program stored in the memory of the signal input processing device of FIG. 3. 2.31...CPU, 3.32...Memory, 4.3
3... Input boat, 5, 12. 34... Output boat, 6... Contact, 7... External high voltage power supply, 9.13.
... Photocoupler, 16 ... Potential conversion circuit, 17 River cutoff circuit, 30°A ... Computer circuit, 35 ... Delay circuit, 36 ... Day latch circuit, 37 ... Memory circuit, B. ...External signal input circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts. Deputy Masuo Oiwa (and 2 others) 2nd
Figure 5”/7

Claims (1)

[Claims] While inputting an external contact signal and outputting it via a potential conversion circuit, a means for interrupting the contact signal is provided at a stage before the potential conversion circuit, and when the interrupting means is interrupted, the rationality of the input signal is checked and the potential is changed. In a signal input processing device for detecting an abnormality in a conversion circuit, in addition to the output of the potential conversion circuit, when the cutoff means is not operating, the output of the potential conversion circuit is output as is, and the cutoff means is operated. 1. A signal input processing device comprising: storage means for holding and outputting the output of the potential conversion circuit immediately before a cutoff operation when the potential conversion circuit is in operation.