Hello everyone.

I try to use SFC 108 (ALARM_D), but I don't understand what kind of information I should pass to the variable "SD". In the offline help Step7 says that SD is "associated value" and nothing more. I expect it to contain text library index and timestamp and maybe something else.

Where can I find out what "SD" variable should be contain?

You have to read the document "Programming with STEP 7" Chapter # 16 about Messaging. In section "16.4 Tips for Editing Messages" you will find a description for using data in SD input. With this information, you can set using this data.