SU1762292A1 - Interface unit for digital control system - Google Patents

Abstract

Use as a matching circuit of input circuits for numerical control systems, programmable controllers, and so on for converting sensor signals to logical signals. SUMMARY OF THE INVENTION The matching block contains measuring sensor 1 OR 2 epic element, current limiter 3, optical connector 4, large-scale amplifier 5, block 6 sample key element 7, source 8 and 9 diagnostic signals 1-2-3-4-5-6, 1-7-4, 8-2, 9-7 1 Il 1 tabl

Description

The invention relates to automation and computing and can be used as an input circuit matching device for numerical control systems, programmable controllers, and so on for converting sensor signals to logic signals.

Arrangements for matching input circuits are known, which include a current limiter and an optocoupler. The main disadvantage of such schemes is low reliability.

The closest in technical essence to the proposed device is the sensor transmitter selected as a prototype for sensors of input signals of a digital control system containing a series-connected rectifier, a current limiting circuit, an optocoupler, an operational amplifier and a control valve.

The disadvantage of the prototype is the lack of operational control of the correctness of the system. Sensor input circuit. If there is a malfunction in the sensor-input system, in order to detect the fault point, it is necessary to disconnect the sensor from the input circuit to connect a diagnostic device, which leads to an increase in the time of simple equipment during diagnostics and repair

The aim of the invention is to expand the scope and increase reliability due to the possibility of operational control of the correct operation of the device.

The goal is achieved by the fact that in a matching unit for a digital control system containing a measuring sensor a current limiter is connected by an output to the first output of the light-emitting element of the optical connector, a photosensitive element of which is connected by the first and second outputs respectively to the positive terminal of the voltage source and through a large-scale amplifier

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To the information input of the sampling block, the output of which is the output of the matching block, and the input of the sampling control is the control input of the matching block, two additional diagnostic signal sources are introduced, the key element and the OR element, the first and second inputs of which are connected to the first outputs, respectively sensor and the first diagnostic signal source, and the output is connected to the current limiter input, the first output of the second diagnostic signal source is connected to the control input a key element through which the second terminal of the light-emitting element of the optical connector is connected to the second terminals of the measuring sensor and the first and second sources of diagnostic signals.

The drawing shows a block diagram of a matching unit for a digital control system.

The matching unit contains the measuring sensor 1, the IL-2 element, the current limiter 3, the optical connector 4, the scale amplifier 5, the sampling unit 6, the key element 7, the first 8 and second 9 sources of diagnostic signals. The first output of sensor 1 is connected to the first input of the element OR 2, the second input of which is connected to the first output of the first source 8 of the diagnostic signal, and the output to the input of current limiter 3. The first output of the light-emitting element of the optical connector 4 is connected to the output of the current limiter 3, and the second output through the key element 7 to the second output of the sensor 1. The photosensitive element of the optical connector 4 is connected to the positive terminal of the voltage source by one and an amplifier 5 to the information input of the sampling unit 6, the sampling control input of which is the control input of the matching unit. The control input of the key element 7 is connected to the first output of the second source 9 of the diagnostic signal. The second terminals of both sources 8 and 9 of the diagnostic signals are connected to the second terminal of the measuring sensor 1.

The matching unit for the digital control system converts the signal from the output of the measuring sensor 1 to the logic level signals necessary for the operation of the digital control system and galvanically isolates the power supply of the sensor 1 and the reference circuits of the diagnostic signals from the amplification circuits

and generating logical signals. Current limiter 3 reduces the output voltage of the measuring sensor 1 to a level that creates a current in the light-emitting element of the optical connector 4, at which a single signal appears at the second output of the photosensitive element of the optical connector 4 at a high voltage level at the output of the sensor 1. In the digital control system, several matching units are used, they are combined on output using sampling units 6. The selection of the desired matching unit is performed by applying a signal to the control input of the corresponding matching unit.

The matching unit operates in two modes: the mode of polling the state of the measuring sensor 1. cyclically performed by the digital control system (not shown), and the mode of diagnosing, which is carried out each time before conducting the polling cycle.

In the mode of polling the state of the measuring sensor 1, a signal similar to the zero signal of the sensor 1 (corresponding to a low level 1 of the signal of the measuring sensor 1) is sent to the control input of the key element 7 from the second input element OR 2 from the first source 8 of the diagnostic signal. The source 9 of the diagnostic signal is given a signal providing the triggering operation of the key element 7. The output signal of the measuring sensor 1 is fed to the first input of the OR 2 element, the OR 2 element passes through and A circuit consisting of a current limiter 3, a light-emitting element of the optical connector 4 and a key element 7. With a single signal from sensor 1 (corresponding to a high voltage level at the output of sensor 1), a single signal appears on the second output of the photosensitive element of the optical connector 4 and when the signal from sensor 1, which must be less than the threshold of the light-emitting element of the optical connector 4, is zero, the second output of the photosensitive element of the connector 4 will be a zero signal. This signal passes the scale amplifier 5 to the information input of the sampling unit 6. A control signal is supplied to the control input of the matching unit, through which the signal from the output of the scale amplifier 5 is transmitted to the output of the matching unit (and then to the control system).

In the diagnostic mode, checking the correct operation of the matching unit

performed by simulating first a single and then zero signal of the measuring sensor 1.

To simulate a single signal of the measuring sensor 1, a signal similar to a single signal from sensor 1 is sent to the second input of the OR 2 element. At the same time, a signal is provided to the control input of the key element 7 that ensures its opening. At the output of the matching unit, the correctness of the passage of this signal in the presence of a sampling signal at the control input of the matching unit is checked.

To diagnose the matching unit by simulating the zero signal of the measuring sensor 1, the control input of the key element 7 is given a signal closing it.

The key element 7 breaks the circuit consisting of a signal source applied to the OR 2 element and the OR 2 element connected in series, the current limiter 3, the light emitting element of the optical connector 4.

At the output of the matching unit, the correctness of the signal similar to the zero signal of the measuring sensor 1 is checked.

At the time of diagnosing the matching unit for both single and zero signals, the state of sensor 1 can be any. A single diagnostic signal from the first source 8 passes through the OR 2 element and causes a current through the light-emitting element of the optical coupler 4, regardless of the signal from the measuring sensor 1, to the first input of the OR element 2. If the diagnostic signal is zero, the open key element 7 is broken A series circuit consisting of sensor 1, an IL-2 element, a current limiter 3, and a light-emitting element of the optical connector 4, so that this circuit is de-energized even if and output from the sensor 1 to a first input of OR 2 unit signal arrives.

At the end of the diagnostics, the matching unit is transferred to the polling mode, for which the second input of the OR 2 element is given a zero signal and the control input of the key element 7 is a signal that ensures the activation of the key element 7.

In control systems, in which, to ensure fault tolerance, two (or more) matching blocks are connected to one measuring sensor, if one of them fails, the failed block is turned off

by closing the key element 7 and removing the sample at the control input of the matching unit.

The table shows the signal states in different modes of operation of the matching unit.

The proposed matching unit is implemented in the form of a hybrid microassembly in which the OR 2 circuit is implemented on a KD 704 AU double unpackaged diode, limiter 3 then ka - resistance deposited on a ceramic substrate, optical connector 4 - optocoupler AOD 120A -1, scale amplifier 5 - two transistors of type KT 3130 B, sampling unit 6 — K 533 LA9-4 microcircuit, key element 7 — KT 3130 A. transistor

Possible implementation of the matching unit with the use of a transistor optical connector, and as a key element - a relay.

The introduction of the operational control of the correctness of the work of the matching unit allows detecting the failure of the matching unit immediately, not allowing further propagation of the failure, and obtaining an economic effect by eliminating. damage due to improper operation of the control object

Claims (1)

Claims A matching unit for a digital control system comprising a measuring sensor, a current limiter connected by an output to the first output of a light emitting element of an optical connector, the photosensitive element of which is connected to the positive input terminal of the voltage source via the first and second z0, respectively, and through a large-scale amplifier to the information input of the unit sampling, the output of which is the output of the matching unit and the control input of the sample — the control input of the matching unit, tlichayuschiy- in that, in order to expand the field of application and increasing the reliability due to the possibility of operational monitoring correct operation, it entered two sources of diagnostic signals, the key element and OR. the first and second inputs of which are connected to the first outputs of the measuring sensor and the first diagnostic signal source respectively, and the output is connected to the current limiter input, the first output of the second diagnostic signal source is connected to the control input of the key element through which the second output of the light-emitting element of the optical connector is connected to the second terminals of the measuring sensor and the first and second sources of diagnostic s , 7 - $ Ј 7th R