KR970005560B1 - Method and apparatus of monitoring for plc - Google Patents

Abstract

Apparatus and method for monitoring a programmable logic controller monitor a state of a programmable logic controller(PLC). If there are many data to be monitored, the apparatus uses a latch buffer, ensures a day time of a programmable logic controller scan time having the same monitoring data, and displays an accurate monitoring information. The monitoring apparatus includes: a data memory for storing a data about a contact point; a monitoring buffer which divides the contact points to be really monitored into two regions, and registers them; a latch buffer which reads a monitoring data from the monitoring buffer by performing a lock when monitoring, and then performs an update of the monitoring buffer by performing an unlock; and a monitoring apparatus which sequentially reads data before unlocking the latch buffer, and displays the data for the user.

Description

Monitoring device and method of programmable logic controller

1 is a block diagram of a monitoring apparatus of a conventional programmable logic controller.

2 is a table of theoretical values for each scan of actual data for monitoring in FIG.

FIG. 3 is a chart of when the nth scan has completed reading data for monitoring in FIG. 1. FIG.

4 is a flowchart illustrating a method of monitoring a conventional programmable logic controller.

5 is a configuration diagram of a monitoring device of the programmable logic controller of the present invention.

6 is an operation flowchart for a monitoring method of the programmable logic controller of the present invention.

FIG. 7 is a diagram of an nth scan when data is completely read by a programmable logic controller (PLC) in FIG.

* Explanation of symbols for main parts of the drawings

11: main body 12: data memory

13: monitoring buffer 16: latch buffer

17: monitoring device

The present invention is for monitoring the state of a programmable logic controller (PLC), and particularly in the monitoring device and method of a programmable logic controller to monitor the monitoring data at the same scan time using a latch buffer when there is a lot of data to monitor. It is about.

The monitoring device configuration of the conventional programmable logic controller includes a data memory 2 storing data for a contact in the main body 1 of the programmable logic controller as shown in FIG. 1, and the data memory 2 for monitoring. A monitoring buffer 3 collecting the contacts to be actually monitored from the monitoring device, and a monitoring device for displaying the monitoring information to the user based on the contents of the contact points monitored from the monitoring buffer 3 of the main body 1 (6). ).

Looking at the conventional technology configured as described above are as follows.

After registering the programmable logic controller (PLC) internal contacts to be monitored by the user in the data memory (2) inside the programmable logic controller (PLC), the monitoring buffer 3 reads and registers only the contacts to be monitored. If the number of contacts is large, the number of contacts that can be registered in one communication frame has a limit, so it is divided into two registers of the first registration area (4) and the second registration area (5).

Then, the monitoring device 6 shows the user to the monitoring screen 7 using the contents of the data in the monitoring buffer 3.

Referring to the operation based on the operation flow chart shown in FIG. 4 again, the number of contact points that can be registered in the communication frame is limited to register in two, so that the first monitoring data is registered first and then the rest If the second monitoring data is registered in the monitoring buffer 3, the first monitoring data is read into the monitoring device 6, and then the second monitoring data is read and displayed on the monitoring screen.

However, in the related art, since the contents registered in the monitoring buffer cannot be taken to the monitoring apparatus at once and are taken through two communication frames, data is theoretically generated as shown in FIG. As shown in FIG. 2, when two communication points are incorrect, there is a problem in that monitoring information becomes inaccurate for a frequently changed contact point because an error data is eventually transmitted to a monitoring device.

Accordingly, an aspect of the present invention is to provide an apparatus and method for monitoring a programmable logic controller capable of monitoring a contact point of a programmable logic controller at the same time.

An apparatus for achieving the above object includes a data memory 1 storing data for a contact in the main body 1 of a programmable logic controller PLC, and the contacts to be actually monitored from the data memory 1 for monitoring. The monitoring buffer 13 to be divided into two areas and the data to be monitored from the monitoring buffer 13 are read and then unlocked so that the buffer 13 can be updated. The latch buffer 16 and the monitoring device 17 which reads and displays the data until the latch buffer 16 is unlocked in turn are displayed to the user.

In addition, the method for achieving the object of the present invention is to register the monitoring data divided into two areas in the monitoring buffer 13, and the latch buffer 16 when the registration is completed in the first step (LOCK) A second step of sequentially reading all the data registered in the two areas and then unlocking the data, and a third step of reading the data of the monitoring buffer 13 and displaying it on the screen until it is unlocked in the second step. To achieve the steps.

Looking in detail with respect to the operation and effect of the present invention configured as described above are as follows.

First, the user stores the data for the contact point in the memory 12 in the main body 11 of the programmable logic controller PLC.

Then, when monitoring by the programmable logic controller (PLC), the monitoring buffer 13 reads only the data to be actually monitored from the data memory 12 and writes the data to the first registration area 14 and the second registration area 15. When registered sequentially, the latch buffer 16 is locked to read and store monitoring data from the monitoring buffer 13.

In the same manner as described above, immediately after reading the monitoring data from the first registration area 14 and the second registration area 15 of the buffer 13, the latch buffer 16 is immediately unlocked (UNLOCK) and programmable logic Allows the controller PLC to continue the update UPDATE to the monitoring buffer 13.

Meanwhile, the monitoring device 17 reads monitoring data from the first and second registration areas 14 and 15 of the monitoring buffer 13 until the latch buffer 16 is unlocked, and displays the monitoring screen 18 on the monitoring screen 18. Display.

Then, it is checked whether or not a monitoring termination request has been entered, and if the termination request has been entered, it is terminated or otherwise, data read through the locking and locking operation of the latch buffer 16 is displayed.

Using this method, although the second monitoring data taken as shown in FIG. 7 is about one scan past from the programmable logic controller (PLC), the value at that time can be accurately displayed on the monitoring screen 18.

Referring to FIG. 6 again for the same process as above, after registering the first monitoring data and then registering the second monitoring data, the latch buffer is locked to read the registered data in sequence.

Therefore, when the registered monitoring data fills the latch buffer 16, the latch buffer 16 is UNLOCKed so that the monitoring buffer 13 registering the monitoring data can update the new monitoring data again. Meanwhile, the monitoring device 17 displays the registered monitoring data on the screen 18 so that the user can view it.

As described in detail above, the present invention can display accurate monitoring information by ensuring that the monitoring data obtained by communicating over the second time when there are a lot of data to be monitored is data of the same programmable logic controller (PLC) scan time. It has one effect.

Claims (2)

A data memory that stores data about contacts in the main body of the programmable logic controller (PLC), a monitoring buffer that registers the contacts to be monitored from the data memory into two areas for monitoring, and a lock when monitoring ( Reads the data to be monitored from the monitoring buffer and then unlocks it, and then reads the latch buffer to update the monitoring buffer, and then reads the data until the latch buffer is unlocked. The monitoring device of the programmable logic controller, characterized in that the monitoring device configured to display and display to the user. The first step of registering the monitoring data into two areas in the monitoring buffer and the latch buffer when the registration is completed in the first step, and sequentially reading all the data registered in the two areas, and then unlocking them. And a third step of reading the data of the monitoring buffer (13) and displaying it on the screen until it is unlocked in the second step.