Tektronix TDS2004B 4-channel scope: NI-VISA Driver doesn't allow CH3 or CH4 to acquire data or set probe attenuation

[hsalem]

Hi,

I have a Tektronix TDS2004B 4-channel digital oscilloscope, and I've been using the auto-generated Measurement Studio .NET wrapper with the supported NI-VISA driver (provided here: tktds1k2k driver download page). 

The driver works flawlessly when I'm using channels 1 & 2, no problems. However, I'm having problems with channels 3 & 4.

• When querying channel names, I get: CH1, CH2, MATH, REFA, REFB (not CH3 or CH4 as expected).
• Cannot set probe attenuation for REFA or REFB channels (error message: "The attribute is not valid for the specified channel  or repeated capability")
• Cannot take measurements for REFA or REFB channels (error message: "Measurements can be taken only on acquisition channels.")

To further troubleshoot, I've used the VISA Test Panel (through NI MAX) and directly talked to the scope with message-based I/O, using the commands from the Programmer Manual:

• I can successfully change CH3 and CH4 probe attenuation, using commands: 

  CH3:PROBE\s10\n 
  CH4:PROBE\s10\n

• I can also successfully start acquisition and get measurements using the proper commands.

So since the scope channels 3 & 4 can be successfully controlled through message-based I/O, that means the control problems are in the C DLL-based IVI driver. It's interesting how the IVI driver uses REFA and REFB, while the message-based I/O uses CH3 and CH4. For my project, I need at least 3 scope channels, yet I can only use the first two right now.

Has anyone bumped into this problem before? Have you found a solution for this?

I'm currently too deep into using the IVI driver, so switching to message-based is not feasible.

Thanks in advance,

Hazim

[oscarfonseca]

Hello Hazim,

I found something similar in another forum post. They recommend:

Under the MAX - IVI DRIVERS | DRIVER SESSIONS | <driver> | VIRTUAL NAMES... 

I deleted all virtual names <--> Channel references and this cleared up all issues.

Can you try this step and let us know your results?

I believe it would be good for us to be able to see your MAX configuration of the driver, as well as the code where you're doing the calls to your instrument (the smallest reproduciuble case).

Regards,