DD224131B1 - CIRCUIT ARRANGEMENT FOR DIAGNOSIS - Google Patents

Description

Field of application of the invention

The invention relates to the field of digital control technology and can be advantageously applied to the diagnosis of digital outputs of programmable controllers including the connection elements to the consumers.

Characteristic of the known technical solutions

From DD-WP 141956 a test device for input modules and output modules of a programmable controller has become known in which at the interface between process and control a SolU / lstvergleich the digital signals is made. Condition signals from checkpoints combined into checkpoint groups represent the responses to status queries during the control process.

The checkpoints are formed by separate outputs of the input or output modules. From the address decoder of the programmable controller, the test points of the modules each an input or output channel are called simultaneously. For checkpoint groups to which gates are assigned, the checkpoints of the input modules of the input channels or output modules of the output channels which are located at the same distance from the central module of the controller are combined. The outputs of the gates are routed to comparators within the central assembly of the programmable controller.

With the test device, the function of the programmable controller can be monitored only up to the EiiWAusgabeschnittstelle and errors are located.

Furthermore, a "device for monitoring the control of a cyclically operating machine" has become known in DE-OS 2260177. The control state is monitored during all functions of the work cycle of a machine by the actual state of switches arranged on the input side and actuators arranged on the output side with that stored in a memory device To this end, separate outputs of the controller and memory outputs are connected to a comparator which outputs a spurious signal in the event of a mismatch of the bit configurations The memory device contains all the control states to be monitored in the form of bit configurations in the order corresponding to the proper operation of a work cycle of the machine. The control core can be monitored by means of this described monitoring device The mode of operation of the switches and actuators is determined by their effect on the Ste indirectly recognizable.

The intended use of a process computer is a high cost of circuit technology. In addition, errors in the controller are recognized only at their impact on the work process.

Today, modern control modules are executed in wear-free or low-wear technology. Failures usually occur on the process side in the form of breakage of the flexible cables, loosening or wear of connectors. Therefore, checking the connections and lines of systems put into operation is of particular importance. Furthermore, it should be noted that diagnostic hardware as well as functional hardware with increasing number of components increases the statistical failure rate of a programmable controller.

Object of the invention

The aim of the invention is to detect errors in the range of digital outputs programmable controllers to the elements of the controlled device or system with simple means and low circuit complexity before they can affect the control process.

Explanation of the essence of the invention

The object of the invention is to provide a circuit arrangement for diagnosing digital outputs of a programmable controller with a central control assembly and connected address and data control including the connecting elements to the arranged on process modules consumers, by means of comparators the actual state of the digital outputs including the connecting elements to the consumers with a predetermined state of the programmable controller is compared both in a to be performed in off-line operation diagnostic routine and in on-line operation during the work program sequence.

This object is achieved in that the controllable via the output amplifier of the programmable controller and via the connecting lines to the process inputs of the consumers of a process assembly are mutually decoupled combined to form a checkpoint, and that a common, connected to the checkpoints of all process modules, Diagnoseausfrageitung to which, by the address and data control via a conjunction clocked by the central control module, bitwise interrogated comparator is connected.

The diagnosis of the digital outputs can be carried out for the entire system in both off-line and on-line operation. It is determined on the single output signal broken down, whether the entire output control to the effective element in the process error-free, works. The function of the digital output control of the programmable controller as well as the function of the connecting elements between the output elements of the controller and the consumers is controlled. An error-free diagnosis allows the operational readiness of the programmable controller.

For bit-serial diagnosis, a diagnostic interrogation signal is formed for each process module. For this purpose, each loadable connection, which can be assigned with control signals, is connected via a diode to a process test point.

The testing of the switching function of the individual output signals and the connection technology to the consumers is done by serial control signals are applied to the process outputs of the programmable controller and thus to the consumer connections.

The functional effectiveness of the individual signal paths is checked by bit-wise interrogation of the diagnostic interrogation signals in the cycle of the control of the process outputs at the consumer terminals. The diagnostic interrogation signal is conditioned via a level adjustment, separated contactlessly via an optocoupler and fed to a comparator, which is clocked by the address and data control of the output control.

The comparison result is fed to the central control module for further evaluation.

embodiment

The invention will be explained in more detail with reference to a drawing.

This shows an embodiment of the circuit arrangement according to the invention for diagnosis.

Referring to the input of each arranged on a process assembly 12 consumer 1 such as lamps, inductive and resistive loads via a respective diode 3,4 and 5 with a test point 10 and the input of each consumer 1 on a further process assembly 13 via one each Diode 6,7,8 or 9 connected to a test point 11.

The test points 10 and 11 are linked to a diagnostic sense line 2, which is guided via a level adjustment 16 and an optocoupler 18 to a one-bit comparator 23. A, connected via an input to the one-bit comparator 23, central control unit 22 is the output side with a display 24, an address controller 19 and a data controller 20 linked. Output lines 15 connected to the process modules 12, 13 via connection lines to the process 14 are controlled by the address controller 19 and the data controller 20 via an output controller 17. Address and data control 19,20 are further connected via a conjunction 21 with the one-bit comparator 23. The assemblies 15 to 24 are shown framed as a control assembly 25 framed by the process page on the drawing.

The circuit operates as follows.

The error-free data transmission from the central control module 22 to the consumers 1 is the condition for the proper operation of a program-controlled system. Prerequisite for this is the error-free functioning of the digital output control, d. H. all control-internal and responsible for the data output modules, as well as the connection lines to the process 14th

Flexible lines and connectors that provide the connection lines to the process 14 are subject to greater mechanical loads than the control assembly 25. Breakage of the flexible leads, wear or disconnection of connectors will result in system failure. It is therefore advantageous first to diagnose the digital outputs of the programmable controller, including the connecting elements to the process modules 12,13 before activation of the system.

In order to be able to check the switching function of the individual output signals and of the connecting elements to the loads 1, a normal data output is provided by the central control module 22. By means of address and data control 19, 20, the individual output amplifiers 15 become serial via the output control 17 used for level conversion and amplification driven. On the drawing 1 is indicated symbolically, which type of output amplifier 15 may be executed in dependence on the type of selected consumers 1, such as transistors, switches or thyristors.

Through the process outputs, each consumer 1 and thus each of the diodes 3 to 9 are controlled in succession via the connecting lines from the process 14 and a signal is supplied to the diagnostic signal line 2.

As can also be seen from the drawing, any number of digital outputs can be diagnosed. Depending on the number of process outputs of the control module 25, a corresponding number of inputs of the consumers 1 via the respective diode to the diagnostic sense line 2 are connected. The spatially close to each other consumers 1 are combined to form a process assembly with a corresponding checkpoint.

The signal on the diagnostic sense line 2 is conditioned by the level adjustment 16, transmitted potential-free via the optocoupler 18 and fed to the one-bit vergletcher 23. At the same time passes from the conjunction 21 by linking two control bits of the address and data control 19; In accordance with the diagnostic signal, the functionality of the checked digital output is indicated by the central control unit 23. If the diagnostic signal and the diagnostic clock signal do not match, the error of the digital output currently being controlled is displayed by the central control module after evaluation. Faulty digital outputs of the programmable controller, worn flexible lines and connectors or even lack of contact with the process modules 12, 13 can be detected more quickly by means of the solution according to the invention. Since the means of the programmable controller are used to address the consumer 1, the circuitry complexity for the solution is low. In addition to carrying out diagnostic routines in off-line operation before processing a control program, a constant diagnosis is possible in on-line operation during an ongoing work program. In the latter case, a signal is reported to the control module 25 from each signal output to the load 1 via the diagnostic line 2. If this signal is missing on the diagnostic line 2, the program processing is interrupted at the central control module 22 and there is the output of an error message. This avoids machining errors and accidents at the controlled device.

Claims (1)

Circuit arrangement for the diagnosis of digital outputs of a programmable controller with a central control module and connected thereto address and data control, including the connection elements to the arranged on process modules consumers, in which the actual state is compared via a comparator with a specified by the programmable controller solitary state, characterized in that the inputs of the consumers (1) respectively of a process module (12, 13) which can be controlled via the output amplifiers (15) of the programmable controller and via the connecting lines (14) to the process are mutually decoupled to form a test point (10, 11), and in that a common, with the test points (10,11) of all process modules (12,13) connected, diagnostic sense line (2) to, by the address (19) and data control (20) via a conjunction (21), clocked by the central control module (22), bit by bit queries comparator (23) is connected. For this 1 page drawing