Hi everyone,
I'm trying to use the LabView instrument I/0 assistant to command and read from two 15 y/o Newport PM500-C motion controllers. The assistant uses VISA connetions to interface with the motion controllers, which are themselves connected with GPIB cables connected to the computer with an NI GPIB-USB-HS adapter. The code works as designed at the start of the program, but, after one or two dozen minutes of running, the assistant begins returning empty strings, instead of the position indicator strings it was happily running before, and I get VISA write error code -1073807339 when attempting to use the VISA Write function within the running VI. When empty strings are returned, the NI spy states that the code is only attempting to "VISA Get Attribute" from all devices on the GPIB whereas it lists that the computer was successfully querying and writing to the motion controllers when correct strings are returned. However, when the VI cannot effectively communicate with the motion controllers, I am still able to query them using the MAX NI-488.2 communicator. Even this sometimes returns "iberr = ENOL
ENOL indicates that no instrument was detected at the specified address. Verify that your instrument is powered on and properly connected to your GPIB interface" though everything is connected properly and I can communicate with the other motion controller on the same GPIB. This message does not return when the communicator is closed and reopened, and the general problem rectifies itself temporarily when the VI is restarted. I am wondering if these interface issues are caused by the obsolescence of the motion controllers, or if there is a way to prevent the I/O assistant from returning empty strings in the first place. Any ideas would be appreciated.
Thanks!