JPH0435764B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a sequence control device, and particularly to a sequence control monitoring method and device suitable for displaying the operating status of a programmable logic controller online.

[Prior art]

Programmable logic controllers are easy to create control circuits that are not available in relay control panels.
It is rapidly being used in the field of sequence control due to its ease of modification.

By the way, one of the features of this programmable logic controller is a program debugging function that checks whether the created sequence control circuit operates as expected, and a monitoring function that monitors the sequence control being executed. This converts machine instructions stored in the memory of a programmable logic controller into, for example, a relay circuit diagram image and displays it on a CRT display.
ON/OFF of each contact of the relay circuit and output coil
This is to display the OFF state.

Normally, this machine instruction word ~ relay circuit converter and
The CRT display is separate from the programmable logic controller, and can be connected to the corresponding programmable controller when needed.
It can be removed from the programmable controller when it is no longer needed.

Additionally, there is a demand for the programmable controller body and the circuit conversion display section to be used over long distances. When trying to control a vast production facility with a programmable logic controller, the programmable logic controller should be installed in a place that does not interfere with production as much as possible, that is, in a corner of the production facility, whereas it is difficult to control the operation of the production facility. However, when monitoring the operating status of sequence circuits, a circuit conversion display section is placed at the production equipment operation panel installed in the center where the entire production equipment can be clearly seen. For this reason, a serial interface is often used between the programmable logic controller and the circuit conversion display unit to enable long-distance communication.

When connecting a programmable logic controller and a circuit conversion display unit using a serial interface, the data transfer speed between the two becomes slow. This has the disadvantage that the response time is slow and it is not possible to accurately monitor very short pulse-like operations that occur inside the actual programmable logic controller using the circuit conversion display section.

The reason why the display response time was slow in the conventional device will be explained with reference to FIG. The CPU 100 of the programmable logic controller receives the state of the field equipment 102 as a digital input signal 103 through the process input/output device 101. The CPU receives this signal via the parallel interface bus 104, performs sequence calculations according to the sequence program stored in the CPU, determines the ON/OFF state of the signal to be output externally, and determines the ON/OFF state of the external output signal. OFF signal to parallel interface bus 104, process input/output device 10
1 to field equipment 102 as a digital output signal 105.
02 sequence control (sequence control in the present invention, which will be described later, refers to this series of processing).

Now, let us consider a case where a circuit conversion display device (monitoring display device) is connected to monitor the input/output status and internal calculation status of a programmable logic controller. 106 is a circuit conversion device with a built-in microcomputer, in which the sequence program being executed by the programmable logic controller CPU 100 is converted into a relay ladder circuit diagram by a well-known method, and is displayed as a video signal 107 on a CRT display 108. Is displayed.

Now, in order to display the ON/OFF state of the input/output, data communication is performed via the serial/parallel data converter 109 to the serial data 110 with the serial/parallel data converter 111 on the programmable logic controller side.

If we look at this display procedure in a little more detail,
Check the ON/OFF status of the relay symbol,
The process of displaying the status as a relay ladder on the CRT screen is as shown in Figure 2.

The first step is to determine the input/output of the CRT display relay circuit.The corresponding relay symbols on the CRT screen (usually sequentially starting from the symbol displayed at the top left) are assigned to which input/output address in the programmable logic controller. The correspondence is determined by the instruction word of the sequence program. Then, it specifies the corresponding input/output address to the programmable logic controller and inquires whether its input/output status is ON or OFF. This adjustment is performed by transmitting the corresponding inquiry input/output address from the circuit conversion device 106 to the programmable logic controller via the serial transfer path and causing an interrupt. When the CPU 100 of the programmable logic controller receives the interrupt command of this inquiry input/output address, it checks whether the signal of the corresponding input/output point is ON from the process input/output device 101.
It takes in whether it is OFF and sends it to the circuit conversion display device 106 via the serial transfer path. This answer is also transmitted via the serial transfer path.

The circuit conversion display unit 108 changes the corresponding circuit by changing the corresponding relay contact or output section pixel in the circuit diagram displayed on the CRT display based on the ON/OFF state signal of the corresponding input/output point. To clearly distinguish whether an element is ON or OFF. Methods for displaying the ON/OFF state of a circuit include changing the brightness of the relevant element (high brightness for the ON part, low brightness for the OFF part), and changing the thickness of the line (thick line for the ON part, low brightness for the OFF part),
There are methods such as changing the display shape of the relay symbol (for example, adding a dot mark to the ON part).

By performing the above steps sequentially for the relay symbols on the screen, ON/OFF status display on one screen is achieved.

[Purpose of the invention]

An object of the present invention is to provide a highly reliable sequence control monitoring method and device that speeds up the display response when monitoring the control state of a programmable logic controller on a display device and follows the operation of an actual device.

[Summary of the invention]

The present invention is a sequence control monitoring method that transmits the execution status from a programmable logic controller performing sequence control to a monitoring display device, and displays the status on a screen displaying a sequence circuit diagram. It is characterized by the following structure.

That is, the monitoring display device transmits the address of a predetermined input/output point in the controller that corresponds to the input point and/or output point (hereinafter referred to as input/output point) of the predetermined sequence circuit diagram displayed on the screen. Make the controller hold them all at once.

Next, the programmable logic controller that collectively holds the predetermined input/output points reads out the status signals of the predetermined input/output points, which are updated according to the execution of sequence control, according to the address and transmits them to the monitoring display device. do. Upon receiving this status signal, the monitoring and display device displays the execution status (ON/OFF) of the corresponding predetermined input/output point on the screen of the predetermined sequence circuit diagram.
OFF) is displayed in an identifiable manner.

As described above, the first feature of the present invention is that the addresses of a plurality of input/output points on a circuit screen to be monitored are transferred to the programmable controller and held all at once.

Furthermore, a feature of the present invention is that when all status signals of the above addresses are read, they are transmitted to the monitoring display device all at once, and furthermore, the controller performs processing so that there is no conflict between sequence calculation and reading and transmission of predetermined input/output points. It's about doing. For this reason, the controller controls the above-mentioned reading and transmission at timings determined by the controller itself, rather than depending on interrupts from the display device as in the past.

According to the present invention, if there is no change in the circuit screen to be monitored, the read address from the monitoring display device only needs to be transferred once for the first time. and,
The controller that holds the address is turned ON/OFF during sequence calculation processing, etc.
Since only the status signals are transferred at once, the amount of data for transmitting the status signals is significantly reduced, and the display response speed can be significantly improved.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

Assume that a relay ladder circuit diagram as shown by solid lines is currently displayed on the CRT display 108. This circuit diagram is a representation of sequence calculation instructions stored in the sequencer CPU 100 converted into a relay ladder circuit diagram. this
A CRT is basically a character display, which is displayed in blocks horizontally and vertically.

Regarding this sequence circuit diagram, we will now discuss the case of monitoring which contacts are ON and which contacts are OFF. The circuit diagram conversion device 106 stores in a CRT symbol position storage table 120 where on the screen the relay contacts and output coils displayed on the screen are located. At the same time, it is determined which input/output point is displayed on the CRT display 108 and which input/output point address of the process input/output device 101, and the serial/parallel signal converter 109 converts it into a serial signal. and sends it to the programmable logic controller 100 via the serial line 110. In the programmable logic controller 100, after the serial/parallel signal converter 111 converts the signal back to a parallel signal, the input/output point address storage section 12
Store in 1.

When this input/output point address storage is completed, an input/output point scanning start signal is transmitted from the circuit diagram conversion device 106 to the programmable logic controller 100 via the serial line 110.
The interrupt from 106 ends.

The controller's CPU 100 recognizes the completion of address storage by receiving the input/output point scanning start signal, and in addition to the above-mentioned sequence control, executes data (status signal) processing of the stored input/output point addresses as follows. .

That is, input/output point address scanner 1
22 starts. In the example of FIG. 3, the point address of input 8 is first taken out from the input/output point address storage unit 121, and stored (updated by sequence control operation) in the input/output data memory (not shown) in the process input/output device 101. Reads the input/output status of the on-site equipment. of course,
Status signals from actual field equipment may be received via the process input/output device 101. This state is then stored in the input/output point data storage section 123. Subsequently, the input/output point address scanner 123 retrieves the next point from the input/output point address storage section 121. In the example of FIG. 3, this is input 3. and input 3
Input the ON/OFF status of point data storage section 1
23.

This procedure is repeated to scan all points registered in the input/output point address storage section 121. At this stage, CRT display 1
Since all the ON/OFF data displayed in 08 has been collected, the contents stored in the input/output point data storage section 123 are transferred to the serial/parallel converter 111, the serial line 101, and the serial/parallel converter. 109 to the circuit diagram conversion device 106. This data is then stored in the input/output point data buffer 125. Once all the data has been stored, the display address scanner 124 starts operating and determines where to display it on the CRT from the display address storage section 120, and the circuit diagram conversion display device 106
The display 108 shows the input/output points of the corresponding part of the circuit diagram.
Displays whether it is ON or OFF.

By the way, if the CPU 100 of the programmable logic controller constantly scans the input/output point data, it will not be able to process the essential sequence calculations, so in reality, as shown in Figure 4, each time the sequence program calculations complete one scan, Perform the above input/output point data processing.
When the data for one CRT screen is complete, it is transferred all at once to the circuit diagram conversion display device 106.

In other words, in the conventional method, the input/output address was determined for each relay symbol and the input/output address was placed on the serial transfer path as inquiry data, which took processing time and increased the response time to display the ON/OFF status on the CRT. was. However, once it is decided to display the input/output ON/OFF status of this circuit diagram, the displayed circuit itself is rarely changed, but only the ON/OFF status of each relay contact or output changes. It is. Therefore, it is a waste of time to send input/output addresses every time, so after deciding what kind of circuit's input/output status you want to monitor, send all the input/output addresses that make up the circuit just once. are transferred all at once, and then transferred from the programmable logic controller to the circuit conversion display device (106 and 108).
The data sent to the monitor/display device (monitoring display device consisting of It can be significantly compressed compared to , making it possible to shorten CRT display response time.

By implementing the present invention, it is no longer necessary to send the input/output point address displayed on the CRT every time as in the past, and the programmable logic controller 1
It is only necessary to send as many bits as the number of input/output points from 00 to the circuit diagram conversion device 106, and the amount of data to be transmitted is approximately 1/2.
100, and the ON/OFF display response time on the screen is a few tenths of a second. Human senses can now completely follow the operation of on-site equipment, and even pulse signals can be displayed satisfactorily.

〔Effect of the invention〕

According to the present invention, the amount of data transmitted between the programmable logic controller and the display device can be significantly reduced in displaying the operation of a sequence circuit. Therefore, transmission of status signals to the monitor screen can be processed at high speed, and a highly reliable sequence control monitoring method and apparatus can be provided.

[Brief explanation of drawings]

Fig. 1 shows a conventional method of a sequence circuit operation display device, Fig. 2 shows a flowchart of the display operation in Fig. 1, Fig. 3 shows a circuit configuration diagram for display control according to the present invention, and Fig. 4 shows a sequence operation. A time chart of signal transmission is shown. 100...CPU of programmable logic controller, 101...Process input/output device, 1
02... Field equipment, 104... Parallel interface path, 106... Circuit diagram conversion device, 108
... CRT display device, 123 ... input/output point data storage section, 124 ... display address scanner.

Claims (1)

[Scope of Claims] 1. A sequence control monitoring device comprising a programmable controller (hereinafter referred to as a controller) and a monitoring display device that displays the execution status of sequence control transmitted from the controller on a screen displaying a sequence circuit diagram, The controller controls one or more input points and/or input points in a predetermined sequence circuit diagram displayed on the screen.
or address storage means for collectively storing addresses of predetermined input/output points in the controller corresponding to output points (hereinafter referred to as "predetermined input/output points") transmitted from the monitoring display device; comprising a status signal reading and transmitting means for reading out status signals of a predetermined input/output point according to the address and transmitting them all at once to the monitoring display device; and a conversion means for associating a predetermined input/output point in the controller with a predetermined input/output point, and a state signal of the predetermined input/output point transmitted from the controller and associated with the predetermined input/output point by the converting means is identifiably displayed on a screen of the predetermined sequence circuit diagram. A sequence control monitoring device characterized by having a display means for displaying. 2. The sequence control monitoring device according to claim 1, wherein the address of the predetermined input/output point in the controller is an address of the predetermined input/output point indicated in a sequence program. 3. The address of the predetermined input/output point in the controller is the address of the predetermined input/output point of a process input/output device.
Sequence control monitoring device described in Section 1. 4. Claims characterized in that the status signal reading and transmitting means includes temporary storage means for temporarily storing each status signal read out in order to collectively transmit the status signals of the predetermined input/output points. The sequence control monitoring device according to item 1. 5. In a sequence control monitoring method in which the execution status of sequence control is transmitted from a programmable controller (hereinafter referred to as controller) to a monitoring display device and displayed on a screen displaying a sequence circuit diagram, the monitoring display device one or more input points and/or
Alternatively, an address of a predetermined input/output point in the controller corresponding to an output point (hereinafter referred to as a "predetermined input/output point") is transmitted and held collectively in the controller; Reading the status signals of predetermined input/output points according to the address and transmitting them to the monitoring display device when the status signals of the predetermined input/output points are complete, and the monitoring display receiving the status signals transmitted from the controller. A sequence control monitoring method, characterized in that the device displays an execution state of the predetermined input/output point corresponding to the predetermined input/output point on a screen of the predetermined sequence circuit diagram in an identifiable manner. 6. In a sequence control monitoring method in which the execution status of sequence control is transmitted from a programmable controller (hereinafter referred to as controller) to a monitoring display device and displayed on a screen displaying a sequence circuit diagram, the monitoring display device one or more input points and/or
Alternatively, an address of a predetermined input/output point in the controller corresponding to an output point (hereinafter referred to as a "predetermined input/output point") is transmitted and held in the controller all at once, and the controller updates the address of the predetermined input/output point in accordance with sequence control. reading a status signal of a predetermined input/output point according to the address in a manner that avoids conflict with a sequence operation and transmitting it to the monitoring display device, and the monitoring display receiving the status signal transmitted from the controller; A sequence control monitoring method, characterized in that the device displays an execution state of the predetermined input/output point corresponding to the predetermined input/output point on a screen of the predetermined sequence circuit diagram in an identifiable manner.