I've now used the FB Protocol. I followed the guide in the instructions. I've initialized the ethernet card and the socket 0 during powerup, and also the protocol. Socket 0 is initialized as TCP and to port 26864 (This is the default listening port on the Sitemanager).
Whenever there is an alarm that should trigger an alert message, I use the connect socket 0 FB and then the Send TCP FB.
In the Sitemanager logfile, I can read that it has received a message request from the Visio, but that the request times out because the request is incomplete. I am guessing that the message format from the Visio might not be correct? I am not sure how to be able to do this. Does the message have to be send on specific socket or port from the Visio perhaps?
Edit: I made it work. It had to do with the timing of sending the message. I was trying to send the message before the socket was properly connected. If I used the SB for "socket connected" as a trigger for sending the message, it worked.