NI4070 PXI niDMM_Initiate / niDMM_FetchWaveform does not work after niDMM_reset

[Webserver81]

Hello together!

I'm using a PXI 4070 DMM and wants to use the external trigger on the AUX connector to sample 5000 values. Therefore I use the driver functions niDMM_initiate together with niDMM_FetchWaveform to get the samples. I used this configuration in former applications with driver NI DMM 2.5 but now I upgraded to NI DMM 2.9 and following occures:

1. Init DMM (Ok)

2. SetUp DMM (External Trigger, Trigger Timeout, Measre Waveform, Number of Samples...) (Ok)

3. DMM Initiate (Ok)

4. FetchWaveform and perform trigger signal (Ok)

If the trigger does not occure the function runs in timeout and I get a failed

Now when I perfom a reset of the DMM with niDMM_Reset and after that I repeat steps 2-4, the FetchWaveform function does not wait for the trigger signal. Instead of this the function returns with the samples and without an error code. To get the system running again, I have to perform a re-Initialization of the DMM.

Does anybody know what's going on here? As I said, it works with NI DMM 2.5 but not with DMM 2.9...

[Brandon_G. · Accepted solution]

Hi Webserver81,

There is a known issue that was found in the NI-DMM 2.9 driver that inhibits trigger routing after performing a reset.  To prevent this, after calling niDMM reset, try placing a niDMM Configure Trigger and set the source to something else other than the AUX connecter.  Then, setup your DMM as you did before in steps 2-4.  Please let us know the results after trying this and we can troubleshoot further if the problem ends up being something else.

Thanks Webserver81,

Brandon G

[Webserver81]

Thanks! This workaround works fine!