check variables while write before excepting in the PLC

[Anonymous]

Hi

I have tried to publish variables to the datalayer from the PLC and it works just fine👍. But I am looking for a functionality in the PLC which is similar to the "onWrite" function in the SDK for C/C++. When a user tries to write a value to the datalyer I want to make some sanity checks before I accept the new value in the PLC. Is it possible to solve somehow in the PLC?

[LiuPengfei]

Maybe you can try plc library: CXA_Datalayer. You can use DL_WriteNode to write value to a datalyer.

[CodeShepherd · Accepted solution]

In general I would say that you make a internal working copy of the variables published to the Data Layer. If the value gets written your PLC code can react to it and only if your checks are fulfilled you take to your internal program. Otherwise you write the last known value.