Detecting closed PN Connection on 300 PLC

I was wondering if anyone has experience with detecting when a connection when using Profinet on a 300 series Siemens PLC?

I am using the FBs TCon & TDiscon and am unable to detect the loss of connection if the connection is dropped out ungracefully.

Any advice would be appreciated.

Cheers
JD

Not sure, but if you call TCON with REQ=FALSE, does it then update STATUS with the connection status without doing anything else ?
If so, you can call it with an appropriate interval to get the connection status.

Cheers for your advice Jesper.

I am currently doing what you suggested. But it doesn't appear to update the STATUS if the software the PLC is communicating with doesn't gracefully close the connection.

I guess that you can know if you try TSEND, and it reports an error in the STATUS.

Maybe the problem is that you dont want to attempt a TSEND if the connection is not OK, or you dont use TSEND cyclically.
I have implemented my own error checking with other protocols, in the way that there is a header with a telegram counter that is being sent cyclically, and returned to the sender cyclically. By comparing the returned telegram counter I could detect a lost connection. Also, in the header is information about the net data content. In that way you send empty telegrams with no other purpose than testing the connection.
Maybe something for you. But I do think that it should not be necessary to implement ones own error checking.

It is an interesting problem to which I would also like to know the best solution.

I will review my code to check code o see if TSend can assist in the detection.

My issue needs to be detected before the reciept of a telegram after reconnection. I have used cyclic numbers in headers for the current telegrams but not for future ones. Thanksfor the suggestion.