I need to communicate with a BK instrument Model 1823A which has a RS232 port. I’m using a RS232-to-USB converter based on the latest Prolific chip set. When using the software that comes with the 1823A it works fine for reading and writing data. But when I use VBA code to do this via NI Visa, I cannot read or write data. I have tried two different NI Visa drivers for the 1823A but no luck.
When using NI Max to debug, it sees the RS232-to-USB converter but not the instrument. NI Max acts like things are fine, except that reads commands fail. Write commands appear to work in NI Max but the 1823A does not respond so I believe that the 1823A never really receives write commands.
I use the same model RS232-to-USB converter for another instrument and it works fine with NI Visa when using VBA code. The only difference I can see is that 1823A doesn’t support IDN to identify itself. My questions are:
- If the 1823A cannot identify itself when queried, how will NI Visa know what instrument it is dealing with so that NI Visa can make communication work?
- Is there any way in NI Visa to force an association between the 1823A NI Visa driver and the port assignment so that NI Visa will know what instrument it is dealing with?
