I have been testing your code (after having done some modifications to your code as I do not have a FP module available) on two PCs that both are connected to the same network switch. I notice that you use very short delays in the VIs especially if the network connection cannot establish after e.g. the network cable was unplugged. After unplugging the network cable from one PC and putting it in again (disconnection time was about 30 seconds) the TCP/IP connection was not re-established and I had to power off the switch and power it up again (The switch was dead.). Then the network connection was reestablished.
To make the HMI..VI smarter, I inserted a delay of 1000 ms that only executes in case of a TCP error. (The delay might be even too few depending on your net
work and the associated hardware.)
Your RT..VI is configured to create a listener for an incoming connection for 1000ms. I had to create a similar scenario than yours at the end of 2003 with a cFP-2020 and - to my experience - it typically will not reliably catch a listener in a that short timeout. If I remember correctly, none of the networking timeouts I specified on the cFP-2020 were less than 10000 ms and all of the networking VIs and functions that I used were placed in "background priority" VIs.
As you see: I do not have a solution for your scenario, but I hope that this was helpful.
