Had to boot EX which seems to be a biweekly occurrence. The problem aren't the PLCs or the hardware interface but the communications. The tcioc stops updating with a "No DS mailbox available" error message. This is always preceded by numerous "CAS: UDP  recv error". So far, the only way to fix it is to reboot. I did notice that h1ecatx1 runs the Windows firewall whereas the c1 and y1 run a commercial product.