Supplying CAN devices with bus power

[dabramson]

Hello everyone,

Is it possible to provide bus power to a CAN device with a PCI-CAN Series 2 card? 

The manual is a little confusing in this matter.  Table 4-1 in the manual states that V+ is "Optional CAN power supply if bus power or external VBAT is required."  This makes me think that I can supply a CAN device with bus power from the card's internal source (as long as my jumper is configured for internal). 

A few lines later the following statement is made: "V+ supplies bus power to the CAN physical layer if external power is required...it is not necessary to supply V+, unless you have configured the VBAT jumper for EXT."  This makes me think that V+ has nothing to do with supplying power to devices, and only with powering the bus on the card itself.

If it is not possible to supply bus power with the NICAN card, what is the recommended method for powering a device on the same CAN network (assuming the device is not powered somewhere in its own circuitry)?

Thanks for any help,

Dave

[chris_amadasun]

Hi Dabramsom,
the part of the manual that I assume you are referencing is:

    "V+ supplies bus power to the CAN physical layer if external power is
    required. All High-Speed Series 2 PCI, PXI, and USB hardware is powered
    internally, so it is not necessary to supply V+, unless you have configured
    the VBAT jumper for EXT."

The PCI-CAN/2 cards can be powered either internally or externally.
To power the device externally the VBAT jumper should be configured for EXT,
now your card will be powered by an external source, your card cannot be
configured to be the source for another device. Please reference the following KnowledgeBase:
What Do the Power Jumper Settings on the NI-CAN Cards Mean?
   
As for powering your CAN device it really depends on your device; what are the power
specifications? Can you consider using a battery?

I hope this answers your questions.

[dabramson]

Christian,

  Thanks for your quick response.  I was pretty sure that I could not power my device with the card, and you confirmed my suspicions.  I now have an external power source for my Can device and everything is working fine (still powering NICAN with internal source).

Thanks again,

Dave