How do you access higher channels on the Xantrex XDL35-5TP or the TTi QL355TP power supply?

[LByrd]

I am using a Xantrax XDL35-5TP triple power supply, which is the Canadian version of the TTi QL355TP supply, in an automated test under GPIB control. Channel one is no problem, but I get an error of "Repeated capability lists cannot be modified after attibues have been added to them" when I try to use channel two . The error can be tracked down to the IVi_AddToChannelTable function. The instument is responding with the proper ID and model number, but the driver still cannot accept that there is more than one channel on the supply.

Is there something that needs to be added in the InitWithOptions function to indicate that there are multiple channels? Is there sample code showing mu
ltiple channels in use that I can download as an example?

Thanks to all for your time and effort.
Lynn Byrd

[ScottieB]

Hello Lynn,

It sounds like this might be an error in your instrument driver. You didn't say where you got this instrument driver, but I checked our instrument driver library at www.ni.com/idnet and couldn't find one for the XDL35-5TP or the QL355TP. If you did download this driver from our website, please let me know where you downloaded it from by providing a link so that I can see exactly what the driver is doing itself.

Usually, InitWithOptions would query the instrument to see which model it is and then setup the channels accordingly, so your setup should be minimal. This is something that the intrument driver author would be able to tell you, so all we have to do is figure out who that is, whether National Instruments or a third party.

Let me know.


Scott B.
Applications Engineer
National Instruments

[LByrd]

I believe that you are correct about the driver itself being screwy. The driver was downloaded from the manufacturer of the PSU, Thurlby Thandar Instruments (TTi), from their driver site at http://www.ttinst.co.uk/downloads/drivers-download.htm. Note that the Xantrex isn't actually listed there either. It is the last item on the list, the QL-P series, and the first indication that you actually have the correct driver is when you run the .msi file and the Xantrex supply is listed on the splash page.

Honestly, I think that they released the beta version. I have finally gotten it to work, but had to attach the TQLP.c file to my project list, then edit it so that the defined channel list (line 53 if you ever need it) comes up for both channel 1 and 2 being valid (
"1, 2"), instead of just channel 1 ("1"), then remarking out line 535 so that the Ivi_AddToChannelTable function never gets called.

The solution is ugly, and I really hope that there is a better way, but this is the best that I've managed so far. At least now the program is working.

[msaxon]

We supplied this driver to Xantrax (via TTi), but I'm afraid for contractual reasons we cannot address this problem directly :-(. You will have to get support via Xantrax.

--
Martin.

[msaxon]

PS - we will flag the problem to TTi from our end as well.

--
Martin

[LByrd]

Update: The first response from Xantrex was "works fine for us, problem doesn't exist". I think that they may still be looking into it. One thing that someone pointed out to me is that many drivers for LabWindows/CVI are version sensitive. My thoughts that this was a beta driver may have been totally backward. If the driver had been written to support CVI 5.0 or earlier (pure conjecture on my part), me using CVI 6.0 may be part of the problem. In the meantime, modifying their .c file seems to be the only thing that works (see my comment above from 5 April).

[msaxon]

Can you tell me exactly what ID string the instrument returns?

--
Martin

[msaxon]

Sorry to reply to my own comment, but I just thought of a couple more things.

(1) The driver was developed in CVI 6, so that is not the problem here.

(2) I see you have had a slightly similar problem with another instrument. It might be worthwhile investigating whether your IVI installation is broken, perhaps by re-installing or trying a different PC?

--
Martin