use of two DMMs on a PXI chassis

[nitad54448]

Hi

Maybe not direclty a Labview question, but many of you may be familiar with my issue so please allow me...

I have two DMMs (Keysight 9183A) amont other devices on a NI 1033 PXI chassis. I would like to use these two to trigger measurements at the same time. However, it seems the measurements are sequential (by looking at the timestamps of output error clusters) even thow the trigger is sent in parallel to both DMMs, they are wired in parallel.

Do you have any idea how to achieve measurements at the same time?

(Already asked Keysight support, still waiting for an answer).

Thanks

[santo_13]

Yes, you can individually control each of the instruments in parallel in a PXIe chassis, just have to program it correctly in your code.

Without seeing the code, it is not possible to guide you.

[nitad54448]

Hi

I am also expecting to use the devices in the PXI chassis as independent and the other three instruments can be controlled independently, but not the two Keysight DMMs.

I will add three vi's that illustrate my point.

The test_in_parallel.vi should initiate the two DMMs at the same time then, the reading of a voltage by each DMM should be at the same time (I am not looking at below msec resolution..). The timing difference is about 6 seconds, this is because the DMMs are initialized one by one (actually I can hear the relays for each of them).

The second vi (test_init_in_series_) initialize the DMMs one after the other then start a reading which should be at the same time for both, but they are not (the timing difference is about 400 msec). The behavior is the same as the third vi (test_in_series) in which init and reading are done sequentially.

I would be thankful if you develop what you mean by "program it correctly".

Regards

[nitad54448]

Hi

I am replying to myself so maybe other people have this same (too simple) problem.

I changed the properties of the reading vi's in "Pre-allocated clones" and now it works as expected.

thanks

[santo_13]

---

@nitad54448 wrote:

Hi

I am replying to myself so maybe other people have this same (too simple) problem.

I changed the properties of the reading vi's in "Pre-allocated clones" and now it works as expected.

thanks

---

My next step was to install the driver to see if the driver VIs were re-entrant for parallel use. You investigated on the right track.

I would go with shared clone reentrant instead of pre-allocated clones. Do feedback to Keysight on the driver bug that limits users from parallel use of the driver VIs.