Our application uses an ENET-485/4. Ports 1-3 are used to talk with communications equipment, and port 4 is used as an ENET-485/4 self-test port. Our application opens ports 1-3 and polls the equipment (writes a poll request, and then reads back the poll response). Port 3 is polled every 10 msec, and either port 1 or port 2 is polled every 25 msec. Every 2 seconds, port 4 is opened (CreateFile) and then closed (CloseHandle) in order to ensure that communications to the ENET-485/4 are OK. Should the open operation on port 4 fail (e.g., due to ENET-485/4 power-off or network disconnect), our application enters an error recovery process whereby the open handles on ports 1-3 are closed (CloseHandle) in order to terminate the I/O operations. Our application then continuously attempts to re-open all four ports.
This application has successfully run for many days at a time in this manner, but occassionally, the open request on port 4 fails with error code 1450 (ERROR_NO_SYSTEM_RESOURCES). As a result, the error recovery process described above is entered. Each attempt to open any port results in error code 1450. During this time, the port LEDs on the ENET-485/4 are not lit. Running the NI Serial diagnostic utility is unsuccessful.
This popup appeared after one of these apparent ENET-485/4 lock ups.
The apparent ENET-485/4 lock up is described in thread http://forums.ni.com/ni/board/message?board.id=140&message.id=18253.
