Chapter 3 Easy Programming Makes Better Project
Issue Time:2017-06-17

SETP_Ⅴ、Programming Optimization——Reducing the PLC operation load

Scan period of PLC plays a crucial role in programming operation, which makes sense in the application that requires higher respond. It is a common sense that the more steps of PLC programming needs, the longer time for scan period, as a result that optimization is needed.

The below program could be removed when performing device: basic date operation, manual operation, upload and download of recipe.

Take an example of E-cam program. The program owns 2099 steps but only 242 steps are performed, the scan period is 0.2ms-0.5ms.



How to optimize: parameter of M8002 should be programmed in subroutine as power-up initializing because it is only performed once.


P0 Initialize


Screen 5 and screen 6 are mechanical and process parameters, they will not change when the device is running automatically.



The screen register is D90. In other words, when in the fifth screen, the device is not running automatically, PLC will perform the operation of process parameters(electronic cam table).


When in the sixth screen, the device is not running automatically, PLC will perform the operation of mechanical parameters.


图片11-11Before optimization, the scan period of PLC reaches 1.3ms~1.9ms because of large date of CAN table. But it will reduce to 0.3ms~0.5ms after optimization, which surely can decrease the operation load and improve the stability of equipment.

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