How can I redirect VISA commands to a file?

[zep]

I have a program developed that connects to a power supply using VISA but I want to debug it without the actual equipment and whithout changing the VISA blocks.
I've tried to change the equipment's address to LPT1 - set on 'Printers' as a inexistent generic printer port - hoping that I would be given the choice of printing to a file. It didn't work!

[Dan_Mondrik]

Zep:

Changing your resource string to ASRL10::INSTR (or using the alias LPT1) just uses the Win32 serial API that happens to work when sending data to a local printer. As you noticed, it does not tie into the printing API, and we do not plan to add such support.

However, if all you are trying to do is see what commands are getting sent, the best tool to use is NI Spy. It is available on Win32 and comes with NI-VISA (many other NI API's support NI Spy as well). Just launch NI Spy from the Programs>>National Instruments section of the Start menu, and turn capture on. Then run your program as normal and you will see calls to viWrite. This is the actual data being sent to your program.

Obviously if your setup uses things like flow control, you w
ill need to disable that if the device is not connected. Similarly, if your application tries to read data, that will obviously fail, so this may not get you very far. Perhaps your best bet is to use an IVI driver (if available) and run it in simulation mode.

Dan Mondrik
Senior Software Engineer, NI-VISA
National Instruments