When ever I have problems talking to a device, I open up a Visa Test Panel in MAX (Devices) for the device.
This allows a basic check by writing (viWrite tab) and reading (viRead tab) to/from the device, it's a bit like
using Hyperterminal but you get to check the NI way.
Following up in case anyone else's search leads here.
I'm controlling an Omega CN606 with a USB comport adaptor.
It worked just fine with a LabView example found on these boards, but the equivalent CVI failed.
The issue was termination character.
Either the adaptor, or its driver, or CVI is appending it automatically.
The LF specified in the device manual and appearing in the LabView Configure Serial Port should be omitted for the command string I send from my CVI program.
If it is there, it fouls communication.