Instrument Control (GPIB, Serial, VISA, IVI)
NRP-NI-VISA passport : NI-MAX vs VISA-C vs VISA-COM
I received a R&S NRP-Z92 USB power sensor.
R&S advises to use NI-VISA, their NRP Toolkit and their NRP-NI-VISA passport to communicate with this power sensor.
Using NI-MAX 5.3, the power sensor is automatically detected as RSNRP::0x0062::142056::INSTR and using VISA Interactive Control I'm able to connect to the VISA resource and perform the initial interactive tests ... 
Using VISA-C, everythings works fine too ...
Using VISA-COM, the VISA resource RSNRP::0x0062::142056::INSTR shows up as part of FindRsrc, but when I try to connect to that resource, I get a VISA-COM error 80040154, which appears to indicate that the "Class is not registered". As such I tend to conclude that the NRP-NI-VISA passport provided by R&S does not support VISA-COM. Enabling debugging at the level of the NRP-NI-VISA passport does not provide any information (it only shows that it responds to the FindRsrc and when a session is opened using VISA-C ... nothing logged when trying to open a session using VISA-COM).
The problem is that I need to integrate this power sensor into a .NET application, which uses Ivi.Visa.Interop (and as such VISA-COM) to communicate with different instruments. So at this moment I'm unable to do so ... 
I already logged this to R&S support (no feedback yet), but I wanted to get some feedback from the knowledgeable VISA experts I know to be out there and reading this forum :
1) do you think my conclusion is correct (VISA-COM not supported by the NRP-NI-VISA passport) given the fact that I didn't experience any problems while installing NI-VISA and the NRP-NI-VISA passport ?
2) is NI-MAX capable of successfully opening a connection to this VISA resource, because it tries both VISA-C and VISA-COM or perhaps uses VISA-C by default ?
3) suppose I need to stick to VISA-C for the R&S power sensor (using PInvoke in combination with Visa32.dll from the .NET application), would it be OK to communicate to all other instruments using VISA-COM (and its resource manager) while communicating with this power sensor using VISA-C (and its resource manager) within the same application ?
As background : NI-VISA 5.2 installed, no other VISA installed on my laptop (running Windows XP SP3). I also found some posts referring to error 80040154 caused by 32bit drivers being used in a 64bit application, but this is not the problem in my case.
For those who stayed with me upto this point ... thanks and for those who are able and willing to provide some useful feedback, an extra thank you.
Regards,
Frans
Did not expect to receive a reply after ~5 years 
Quickly had a look at the approach I took at that time: using the example C# code which can be downloaded from the R&S website and using the R&S NRP-Z Power Sensor VXI Plug&Play Instrument Driver Help, which is installed as part of the VXI PnP installation, where I renamed the PInvoke class to RSNRPZ_PnP to create my C# PowerMeter_RS_NRPZxx class.
