JP2522815Y2 - Programmable controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a programmable controller that automatically controls a device to be controlled.

[Conventional technology]

The programmable controller processes an information signal exchanged with the device to be controlled at a control signal level. For this reason, the programmable controller is provided with an input / output device for mutually converting a control signal into a signal level handled by the device to be controlled.

FIG. 2 shows a circuit configuration of an input / output signal system of a conventional programmable controller.

Referring to FIG.
The output data a from the CPU (arithmetic processing circuit) 1 that executes arithmetic processing and control processing is stored and held by the latch circuit 2 of the output unit 50 by the latch signal b, and the on / off latch data of the latch circuit 2 is stored. e is applied to the photodiode 4a of the photocoupler 4 which is one component of the level conversion circuit via the driver 3. As a result, the drive current determined by the current limiting resistor 5 flows through the photodiode 4a, and the photo transistor 4b is opened (on) / closed (off).
Is performed.

The reset signal C resets the latch circuit 2 when the power of the device is turned on / off or when an abnormality occurs, and sets the output of the latch circuit 2 to an initial state.

In an input / output device using a relay instead of the photocoupler 4, the relay contact is turned on / off at the position of the photodiode 4a.
An excitation coil for turning off is provided, and the phototransistor 4b
Is provided with a relay contact.

The connectors 14A and 14B connect the input / output buses for transmitting the above-mentioned signals a, b and c, and the below-described signal d, and can electrically connect / disconnect the input / output devices and the main body of the programmable controller. It is possible. The photocoupler 7 of the input unit 51 converts an on / off signal received from a device to be controlled from a transmission signal level to a control signal level. The level-converted on / off signal output from the phototransistor 7b is transmitted to an input of a bus driver 12 through an integrating filter including resistors 8, 9 and a capacitor 11, and further through a protection resistor 10. The bus driver 12 shapes the waveform of the input signal, and sends out the input signal whose waveform has been shaped by the read signal d of the CPU 1 as data a onto the data bus. Usually, a plurality of such input units 51 and output units 50 are provided in accordance with the number of devices to be controlled.

[Problems to be solved by the invention]

As is well known, the input / output devices of the programmable controller are often installed in places where the working environment is relatively poor. Circuit components on the high-current side in the output device are often destroyed and burnt. For this reason, the user will replace the damaged input / output device with a non-defective one.

However, in the conventional programmable controller, since a plurality of input / output devices are connected to the programmable main unit as described above, if a damaged input / output device is replaced in a live state, a malfunction of the bus driver 12 or the latch circuit 2 As a result, internal signals are wrapped around, and signals on the input / output bus are transiently disturbed. As a result, there is a problem that a normal input / output device malfunctions or an input / output bus control circuit (not shown) of the CPU 1 is secondarily destroyed.

Accordingly, an object of the present invention is to provide a programmable controller which can solve such a problem and can replace an input / output device without any problem in a live state.

[Means for solving the problem]

In order to achieve such an object, the present invention converts an information signal transmitted from a control target device to a control signal level by an input level conversion circuit of an input / output device, and then uses an arithmetic processing circuit in a programmable controller. After performing a sequence operation based on the information signal, a programmable controller that converts an information signal determined by the sequence operation to a transmission signal level by an output level conversion circuit of the input / output device and outputs the transmission signal level to the controlled device. An input connector for detachably connecting an input signal line from the input / output level conversion circuit, and an input information signal transferred to the arithmetic processing circuit via the connector according to an instruction of the arithmetic processing circuit. An output for connecting a bus driver and an output signal line to the output level conversion circuit in a detachable manner. A latch circuit for holding an information signal determined by the sequence operation according to an instruction of the arithmetic processing circuit and outputting the latched signal to the output connector. The connector for input is provided between the input level conversion circuit of the input / output device and the bus driver of the programmable controller main body, and the output connector is provided between the output level conversion circuit of the input / output device and the latch circuit of the programmable controller main body. And that the operation of another input / output device connected to the main body of the programmable controller is not affected even if the input / output device is replaced in the live state.

[Action]

The present invention focuses on the fact that a latch circuit for inputting / outputting information signals and a bus driver, which are conventionally provided on the input / output device side, have a function of cutting off an input signal line and an output signal line. And a bus driver are provided on the programmable controller side. As a result, unless there is an instruction from the arithmetic processing circuit, the signal system on the arithmetic processing circuit side in the programmable controller and the signal system on the level conversion circuit side in the input / output processing device are always in a cutoff state. As a result, even if the input / output device is replaced in the live state, the arithmetic processing circuit and other input / output devices do not malfunction.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a circuit configuration of an embodiment of the present invention. The second
The same parts as those in the conventional example of the figure are denoted by the same reference numerals,
A detailed description thereof will be omitted, and differences from the conventional example will be described.

In FIG. 1, input connectors 15A and 15B between the input section 13 and the programmable controller main body 21 are provided between the photocoupler 7 (input level conversion circuit) and the bus driver 12. Output connectors 14A and 14B between the output section 6 and the programmable controller main body 21 are provided between the photocoupler 4 (input level conversion circuit) and the latch circuit 2. The power supplied to each circuit of each input / output device is commonly connected to the operating power Vcc of the programmable controller main body 21. Therefore, connectors 14B and 15B
Is the sum of the number of input / output circuits and the power supply common line.

In such a circuit configuration, the latch circuit 2 that holds and outputs an output signal functions as a signal line cutoff circuit for the internal bus 22 and the input / output bus 31 on the programmable controller main body 21 side. Bus driver for reading input signals
12 functions as a signal line cutoff circuit for the internal bus 22 and the input / output bus 31.

For this reason, the latch circuit 2 and the bus driver 12 are always operable even if the input / output device is replaced while the programmable controller main body 21 is in a live state, so that an unspecified signal from the input / output device is transmitted to the internal bus 22. No transmission is performed, and other normal input / output devices do not malfunction. Also,
Since the input / output device side of the exchange connection is also disconnected from the internal bus 22, no malfunction occurs.

[Effect of the invention]

As described above, according to the present invention, it is possible to replace a damaged input / output device while the main body of the programmable controller is in a live state, so that it is not necessary to stop the entire system, and a malfunction occurs as in the related art. Not even.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of an embodiment of the present invention, and FIG. 2 is a block diagram showing a circuit configuration of a conventional example. 1: CPU, 2: Latch circuit, 4, 7: Photo coupler, 14A, 14B:
(Output) connector, 15A, 15B (input) connector, 31:
I / O bus.

Claims (1)

(57) [Scope of request for utility model registration] 1. An information processing apparatus according to claim 1, wherein the level of an information signal transmitted from the device to be controlled is converted into a control signal level by an input level conversion circuit of an input / output device. After that, an information signal determined by the sequence operation is converted into a transmission signal level by an output level conversion circuit of the input / output device and output to the controlled device. An input connector for detachably connecting an input signal line of the input signal line, a bus driver for transferring an input information signal to the arithmetic processing circuit according to an instruction of the arithmetic processing circuit via the connector, and the output level conversion circuit An output connector for detachably connecting an output signal line to the circuit,
A latch circuit for holding an information signal determined by the sequence operation in accordance with an instruction from the arithmetic processing circuit and outputting the information signal to the output connector, wherein the latch circuit and a bus driver are provided on the main body of the programmable controller, and the input connector is The output connector is provided between the input level conversion circuit of the input / output device and the bus driver of the programmable controller main body, and the output connector is provided between the output level conversion circuit of the input / output device and the latch circuit of the programmable controller main body. A programmable controller characterized in that even if an input / output device is replaced in a live state, the operation of another input / output device connected to the main body of the programmable controller is not affected.