JPH0348641Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control analog output circuit having a redundant configuration using a standby redundancy system, and particularly to a circuit for detecting an abnormal state occurring in the output circuit.

Currently, in order to improve the reliability of control analog output circuits (generally multi-point output circuits), two output circuits that control a common operation unit are configured in a duplex configuration, and one output circuit (first output circuit) A method has been put into practice in which, if a failure occurs, the control unit is switched to this one and the other output circuit (second output circuit) is used to control the operating section.

FIG. 1 shows the configuration of a conventionally known dual-configuration control analog circuit. In the figure, A is the first output circuit, and B is the second output circuit. Reference numeral 10 represents a bus for exchanging data between A and B and an upper intelligent (not shown), and reference numeral 11 represents an operating section connected to output ends 12 and 12' of this circuit.
In the figure, corresponding parts in the two output circuits A and B are indicated by the same reference numerals, and elements belonging to B are as follows:
Corresponding elements belonging to A are shown with a dash attached to their reference numerals. In the figure, 1 and 1' are first and second output setting devices, and 2 and 2' are first and second constant current circuits.
Each output setter 1, 1' sets the output current I, I' of the corresponding constant current output circuit 2, 2' in accordance with an output current setting signal applied from the upper intelligent through the bus 10. Note that for the sake of simplicity, I=I'. (The current I′ on the standby side is not necessarily I=
It does not have to be I'; it is sufficient if I=I' when switched). 4 and 4' are switch circuits that bridge the output terminals 13 to 14 and 13' to 14' of each constant current output circuit, and the switching position is the same as that of the duplex control circuits 8 and 8'.
Under normal conditions, when one switch circuit is open, the other is closed, and when one output current I is supplied to the operating section, the other output current I' is shorted in its own circuit. 3 and 3' are diodes for blocking the reverse flow of the output current supplied to the operating section 11 from each of the first and second output circuits. 5 and 5' are current value sensing resistors that sense the values of output currents I and I' of each constant current output circuit, and 6 and 6' are conversion circuits for the detection signals sensed by 5 and 5'. 7, 7' are conversion circuits 6,
From the output signal of 6', the output current I of each output circuit,
This is a self-diagnosis circuit that diagnoses whether I' is abnormal or not, and each circuit 7, 7' is controlled by the corresponding duplex control circuit 8, 8' based on the diagnosis result of each diagnostic circuit 7, 7'. A control signal is provided to open/close the switch circuits 4, 4'. Further, the duplex control circuits 8 and 8' are connected to each other, and the output terminal 1 of each output current circuit is connected to each other.
3-14, and 13'-14' are 12 behind 3 and 3'
12', so that while one output current is supplied to the operating section 11, the other output current is short-circuited within its own circuit and stands by.

The redundant control output circuit configured as described above has the disadvantage that even if the control switch 4, 4' portion of either circuit A or B fails, it cannot be immediately detected. Even if a failure occurs in the switch part of the circuit that supplies output to the operation unit (this is called the service side) and it begins to affect the field, it is impossible to detect this early, and Problems still remain, such as that even if the switch part of the side circuit is out of order, the effect cannot be discovered until the service side circuit is switched to the standby side circuit. The present invention has been proposed to solve these problems. In the present invention, each switch circuit 4, 4'
Circuits 9 and 9' are provided to detect the voltages at both ends of the switch, and the operating status of the two circuits A and B, that is, the service/standby status, is diagnosed based on the results detected by these switch voltage detection circuits, and the status is sent to the upper intelligent. The present invention is characterized in that it is equipped with a self-diagnosis circuit that not only transmits the presence or absence of an abnormality in the switch but also causes the duplex control circuit that switches each switch 4, 4' to switch each switch. This invention consists of A, B2
To provide a redundant standby control output circuit capable of early detecting abnormalities in switch circuit portions 4, 4' of the circuit. Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 2 shows the configuration of a circuit that implements the present invention in the redundant control analog output circuit shown in FIG. In the figure, parts corresponding to those shown in FIG. 1 are indicated with the same symbols as in the same figure. The difference between FIG. 2 and FIG. 1 is that each of the switch circuits 4 and 4' is connected between both ends 13-14, 13'-
It is equipped with circuits 9, 9' for detecting the voltage of 14', respectively, and the detection results of 9, 9' are provided to self-diagnosis circuits 7, 7', respectively, and each self-diagnosis circuit 7, 7' It has the function of the diagnostic circuit shown in FIG. 1, and determines whether the operating state of the corresponding control output circuits A and B in each service/standby state is normal by means of switch voltage detection signals given from the detection circuits 9 and 9'. It has the function of diagnosing the problem, transmitting the result to the upper intelligent, and controlling the corresponding duplex control circuit 8, 8' based on the diagnosis result to switch the corresponding switch 4, 4'. A feature of the present invention is that this switching function enables early detection of abnormalities in the first and second switch circuits 4, 4'.

The operation of the embodiment shown in FIG. 2 will be specifically explained as follows. The state shown in FIG. 2 shows a service state in which output circuit A controls the operating section, and output circuit B shows a standby state. The output currents of the circuits A and B are monitored through sense resistors 5 and 5', and abnormalities are diagnosed by self-diagnosis circuits 7 and 7'. Here, a description will be given of a failure state occurring in the switch portions 4, 4' and a failure relief action performed in response thereto.

() Switch 4 On Mode Failure - Circuit A
If it is in service state and working fine, then
The voltage across the switch 4 represents the sum of the voltage drop across the diode 3 and the voltage at the load end,
4 is an on-mode failure, the voltage across it is
Since the value is close to 0V, the voltage detection circuit 9
When a value close to
8', switches 4 and 4' are switched, circuit A is switched to a standby state, and circuit B is switched to a service state.

() Off mode failure of switch 4' - When switch 4' is in standby state and operating normally, the voltage across it is close to 0V, and if this voltage becomes high due to a failure, the diagnostic circuit 7' considers it to be abnormal and transmits abnormality information to the upper intelligent.

() Off mode failure of switch 4 - circuit A
It is discovered by the principle of () when it goes into a standby state due to some abnormality.

() On-mode failure of switch 4' - discovered by the principle of () when circuit B goes into service.

Through the actions of () to () above, any failure in each switch portion can be discovered. In conventional circuits, it was time-consuming to discover failures when the control became abnormal as a result of disturbances applied to the field, but this invention has the advantage of being able to detect failures early. There is.

[Brief explanation of drawings]

FIG. 1 shows the configuration of a conventionally known standby redundant type duplex control output circuit. FIG. 2 shows the configuration of a circuit according to an embodiment of the present invention. A... First control analog output circuit, B... Second control analog circuit, 4, 4'... Switch circuit, 3, 3'... Backflow blocking diode, 11...
Operation unit, 13-14, 13'-14'...output end,
8, 8'... Duplex control circuit, 9, 9'... Switch voltage detection circuit, 7, 7'... Self-diagnosis circuit.

Claims (1)

[Scope of utility model registration request] The first and second control analog output circuits are each bridged by a switch circuit, and an operating section is connected in parallel to the switch circuit via a reverse current blocking diode. a redundant control circuit that separately controls opening and closing of each of the switch circuits; a switch voltage detection circuit that detects the voltage between both ends of each of the switch circuits; 1. Diagnose whether or not there is an abnormality in the operating state of the second output circuit in the service state and standby state, transmit the diagnosis result to the upper intelligent, and control the duplex control circuit based on the diagnosis result;
An abnormality detection circuit for a redundant control analog output circuit, comprising a self-diagnosis circuit for controlling an operating state of a second output circuit.