Hi Nic,

strange thing ...

Is B&R really supporting ISO on TCP? Or just plain TCP?

Do you have the possibility to trace the communication with Wireshark?

They do support ISO-on-TCP. We messed around a bit with the parameters in both the B&R and the S7-319. We found out that if we increase the allocated space for the reception of the data in the B&R it works. Also if I send less stuff it helps too. It looks like the AG_SEND bloc sends all the data at once and the B&R can't manage that

So we increased the B&R receiving buffer from 10 bytes to 50 bytes and I reduced the size of what I'm sending from 10 bytes to 1 byte (I only need to send 1 byte anyway, the rest is spare space).

We don't really know why, but it seems to do the trick for the moment.

Thanks