To modify the PLC timer set value - Database & Sql Blog Articles

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In general, the plc control system often needs to modify some parameters during the use process. The most common one is to modify the set value of the timer. In order to facilitate the operator to modify the set value of the timer, the following methods can be used:

1, using the human machine interface

The PLC can use a touch screen, a text display or an industrial computer as a human-machine interface to facilitate the modification of the timer parameters, but the cost is high.

2, using the built-in analog potentiometer

Small PLCs generally have built-in analog potentiometers for setting parameters. For example, the values ​​of the external adjustment registers D8030 and D8031 of Mitsubishi PLCFX1N and FX1S correspond to the positions of the analog potentiometers. The corresponding registers of the two analog potentiometers of the S7-200 are SMB28 and SMB29. Register A642 corresponding to the analog potentiometer of CP1H.

3. Modify the setting value of the timer with the analog setting function expansion board.

The FX series analog setting function expansion board has eight potentiometers on the FX2N-8AV-BD. The 8-bit binary number set by each potentiometer can be read by the application command VRRD, and the timer and counter settings can be set. value.

4, increase the LCD option board to change the setting value of the PLC internal timer

It is convenient to monitor and change the data values ​​in the PLC and visualize the error status. CP1H, CP1L PLC can add LCD option board CP1W-DAM01.

5. Use the external contact of PLC to set and reset the counter in the program.

Use the rising edge of the button with the up and down counter. When the button is pressed, the register of the up-down counter is incremented or decremented by one. The set value of the timer is the value in the register. The number of presses is determined according to the base time of the timer and the timer. The external contacts that are up and down are separated.