I am using a PXI-4110 power supply to drive my DUT. When I execute an Output Enabled query after initialiazing a session to the 4110, it always returns true even when the output is disabled. A verbose example is attached. Any suggestions on how to get the correct status after initialiazing a session?
(I prefer to open and close the session in each vi. This makes the code portable and easier to maintain in a characterization program.)
I tossed a PXI-4110 in a chassis on my desk this morning and ran the VI. I've attached a screenshot of the front panel after a run. Is this what you are seeing? It appears to me that output enable defaults to true on my system, but is able to be set to disabled, where it remains until re-enabled.
If this isn't the behavior you are seeing (it didn't sound like it based on your description), let me know what version of the NI-DCPower Driver you are using as well as the version of LabVIEW.
You are seeing the same behavior I am. The problem is with measurements 1 and 2 as well as 15 and 16. The output is disabled when the experiment starts and again at step 12. It is enabled at steps 3 and 17. Why, when the instrument session is first initiated, does the module not report that the output is disabled? I would expect the instrument to query the state of the outputs and report on the actual state, not report a default.
I am running LV2016 and niDCPower 15.2 under Win7
From what I can tell this appears to be expected behavior when using the Initialize With Channels VI to open the session. The device initializes into the enabled state, however generation does not occur until the Initiate VI is called. The linked page is somewhat helpful, but I actually like the installed detailed help for the Configure Output Enabled VI better as I feel it explains this a bit more clearly.
Disabling the Output - DC Power Help
If you need the output to be disabled upon initialization you can explicitly disable it immediately after initializing the session.
Thanks Alex, guess I'm stuck with not being able to control and monitor the power supply the way I want. I would expect if I initialized an instrument with reset set to false the state of the instrument would not change. The actual physical state of the PXI-4110 does not change: If I closed the last session with the outputs enabled, they remain enabled at the start of the next session. If I closed it with the outputs disabled, they remain disabled at the start of the next session. But when the module is initialized for a new session, a query reports the outputs are enabled whether they are or not. This leads to an inaccurate state being reported. Since I open and close a session in each subroutine I can't be sure what state the supplies are in by querying the module. It's not appropriate that the module can report an incorrect state. This should be fixed.
I would agree that it would at times be useful to programatically answer the question "Is the led on the device lit?" and from a high level this seems like a simple task. I am working with R&D to determine if there is a way to do this.
That being said, this appears to be an issue primarily because we are closing a session without disabling the output and then opening a new session without resetting the device, allowing it to get into an unknown state. While it may take a little bit more work, it would be best to pass the session handle between steps in TestStand.