Dear community,

I have a program connect to factory i/o simulation, using plc 1214 ac/dc/rly control from hmi ktp700 basic pn. The program is to filling the tank automatically, and I want to make the setpoint to fill the tank is 250 as a default value in HMI display when I run wincc. I have already retain the plc tags and write default value in DB, but why plc always write the value back to initial (0)? Here's the picture in docx, thank you!

Regards, 

Farkim

Hi Farkim,

Hello.

You have set the RETAIN on the input parameter of the FB code block. This input parameter is however over-written by the M-memory tag. This tag is not being retained. The retention of the input parameter in the FB is useless in this use case.

Consider moving away from usage of M-memory tags. Use Global DBs instead. Create a DB that can have all your program settings. Then everything is in one place. 

Later on you can refine this idea by using UDTs.

Do these notes help you?
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Thank you for the response, Hazard_7, Murof, and qwazee! I've already using suggestion from qwazee by write the parameter i have to retain in global DB, instead of using plc tags. Thanks for the recommendation!

Regards,

Farkim