Platform: Window 2000 SP4, NI-Serial Version 3.0
Background: 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.
The Problem: This application has successfully run for many days at a time in this manner, but recently, after running for ~24 hours, the open request on port 4 failed with error code 1450 (ERROR_NO_SYSTEM_RESOURCES). As a result, the error recovery process described above was entered. Each attempt to open any port resulted in error code 1450. During this time, the port LEDs on the ENET-485/4 where not lit. Running the NI Serial diagnostic utility was unsuccessful. Perfmon was being run to record a counter log, and activity on the NiSerE_U process, which had been running at about 1.0-2.5 % of the processor, dropped to 0 %. Power cycling the ENET-485/4 cleared up the problem, and the application error recovery process was then able to successfully reconnect to all ports. The NiSerE_U process returned to its 1.0-2.5 %. The system has been running successfully since then for three days.
It appears to me that the ENET-485/4 device may have locked up. Has anyone seen such an occurrence? Thanks for any help.
