Connecting a USB CAN card to a PXI chassis

[Malcolm_Myers]

I have a PXIe-1078 chassis with a PXIe-8115 controller running Pharlap.  The chassis contains two XNET cards for CAN communications. All the slots in the chassis are full so I cannot add another XNET card. Instead I tried to connect a USB-8473 CAN card to a USB socket on the front of the chassis on the assumption that I could programme it from my LabVIEW project. This appears not to be possible, and I have asked my local tech support who do not feel it is possible.

I should say that MAX can see the card (it sees it as RAW), and I can bring up a VISA reference for it in LabVIEW. However, I cannot tak to the device using the CAN Frame API. I have also connected a USB-6008 card to the chassis and the same applies, you can see it but cannot talk to it.

I appreciate that the 6008 uses DAQmx and that is a Windows driver but has anyone been able to hang a USB card off the front of a PXI chassis and talk to it from LabVIEW?

Thanks

Malcolm

[Sam_Sharp]

I highly doubt it will be possible if you're running LabVIEW RT on the chassis. It would require NI to create Pharlap drivers for the CAN card and it probably shows up in MAX as a USB-RAW device because you can use NI VISA to communicate with USB devices at a low-level - it doesn't actually initialise the appropriate driver (e.g. CAN card) for the device.

You could possibly reverse engineer the USB protocol (but probably against NI license and not for the faint-hearted!) and then re-write it with USB-RAW in VISA.

There is some information about USB devices and Pharlap here: https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000P9MlSAK&l=en-US

Perhaps you could look at having an expansion chassis (with MXI) - I appreciate that it's extra cost, but it would give you more headroom for expansion in the future.

[Hooovahh · Accepted solution]

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@Sam_Sharp wrote:

I highly doubt it will be possible if you're running LabVIEW RT on the chassis. It would require NI to create Pharlap drivers for the CAN card

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Yup it would, and I believe NI CAN 2.7.3 has support for Pharlap.

https://www.ni.com/en/support/downloads/drivers/download.ni-can.html#344635

There maybe other versions.  Basically you need to install this on your host machine, then use MAX to send the program and drivers to the PXI chassis, then you can write LabVIEW code for the RT target that uses those drivers.

[Malcolm_Myers]

Thanks to both respondents; you are both right. Whilst NI CAN drivers do support Pharlap a look at their readme files shows that they only work for PCI and PXI cards, i.e. not for a USB hanging off the front of the chassis.

NI Tech Support have pretty much said I'd have to write my own driver for it which is clearly not something I wish to do. In the end we've decided to use the ExpressCard slot on the PXIe-8115 to add another chassis which will have space for another XNET card.

Thanks for your help, but the hardware solution is the one we'll go with.

Malcolm

[Hooovahh]

Wow really?  That sucks.  Having never used that set of hardware combinations I just assumed it would work.  NI-CAN supports Pharlap so I assumed that was all the hardware that used NI-CAN was also supported in Pharlap.  But I can see why if any hardware wasn't supported, that one wouldn't be.  It is NI's cheap answer to other CAN hardware suppliers and is missing lots of the features other hardware have.  It also hasn't seen much of an update in hardware or software in quite some time.