Variable storage type VAR_VIS in faceplate (FB-FPL)
Has anyone used the variable storage type "VAR_VIS" in the faceplate of the FB-CLASS or OPC_FB-CLASS?
In the manual the VAR_VIS appears as a internal Digivis variable that can be read from or written to Digivis.
I have added a Alphanumeric display that read and write a TEXT Data type VAR_VIS variable.
In Digivis the variable can be modified, but when the faceplate closes and opens, the text change is lost.
Is this the correct behaviour? Should it have kept the change?
Yes, it is correct behavior as it is VAR_VIS is internal digivis variable and is not storage type, you can try using VAR_DPS instead,
"VAR_DPS are local variables used by the user function block running on the process station. They are used to hold intermediate values. VAR_DPS variables can be read from the faceplate. They are used for internal calculation in the faceplate."
If you are using VAR_DPS to pass value to some input/output of UFB, Instead you can read/write that value using VAR_IN or VAR_OUT directly from faceplate and it holds/displays current value from controller. Even if you close and open faceplate.
If incase faceplate is not holding last entered value. In alphanumeric display parameterization you can use “Display value” as predefine value if you do not want some garbage or strange value to be displayed.
Read more information on this in manual 3BDD012504R0401_Eng_Manual_IEC 61131-3_Programming, Page 380.