I've been writing a LabVIEW program to drive 3 axis Newport SMC-100 stepper motor controller for horizontal, vertical and rotational movement. I've implemented a for loop that repeatedly perform .3 degree turn followed by 5 separate horizontal movement until it turns a full circle. The program always fails at tellcontrollerstatus.vi, and gives me VISA 1073807339 timeout error. When I restart the program, it'll tell me there is no RS-232 connection available. The weird thing is, it happens at various loop iteration.
I'm sure the COM port setting is correct. If it's a simple program that tells the rotational stage to make a full turn in 1000 steps, it doesn't have any problem. It's only when I try to control two axes in each loop that I have problem.
I tried implementing delay using flat sequence but it doesn't really help. Eventually, I gave up changing the program and just tried another USB-RS-232 adapter cable. Then the problem is gone.
Although the problem was solved, it's not based on good diagnostic procedure and seems to be sheer luck. I'd like to know if there is a proper way to diagnose this kind of problem?
I always use addrcom to diagnose port. http://www.ontrak.net/adrcom.htm
Also, you can short circuit pin 2 with 3 on DB9 and see weather do you receive the same data you have sent over COM. If you do so it means that your USB-RS-232 adapter cable working properly.