Exchange Variable read bevor write error
Hello,
I have a project with a 2152 and SPLC 1000. I would like to control an output of the safety plc if the status of the machine allows this and the normal plc agrees. For this I use an exchange variable (not safe). This is written by the normal plc. It is linked in the data list with a non-safe variable of the safety plc. If the safety plc wants to evaluate the variable via the EN_OUT function, I get an error. The variable is read before it is written. I know what this means but I can't find the error. The exchange between the PLCs should work and the variable is also initialized in the normal plc.
Feel free to answer in german if you like. Thanks! If needed I can post screenshots etc.
Comments
Hello Albert,
If you create a safety variable (Nonsafe) in the global variable list IEC61131-3, it is created as an output in the global Safety PLC data list by default. Depending on the application, the data direction in the Safety PLC data list must be adapted. It is advisable to create exchange variables in groups in order to have a better overview.
Example
BR
Volker
Hello Volker,
Thank you very much for your help!
Sometimes a mouse click can change a lot. Now the error message makes sense.
I had always hidden the properties of the variable...
BR
Albert