Can cRIO's serial port be used for CAN bus communication?

[dfjuggler]

I would like to control an HVAC system using a CAN network and would like to know if this can be accomplished using cRIO's built-in serial port (NI cRIO-9024 in my case). Is this possible, or would I need a C Series CAN module?

[GPIB_Guru · Accepted solution]

You need a C Series module. Both CAN and Serial use a DB9, but they do not have the same physical layer.

[dfjuggler]

Thanks for your answer, GPIB guru.

To my understanding, the physical layer is compromised of mechanical and electrical specifications, is that right? So, could we say that RS-232 and CAN share the same mechanical specification (in some cases) but not the same electrical specification?

Would it be possible to replicate the electrical signals of CAN using the controller's built-in serial port? I'm guessing that the answer is no (and that it would require fiddling with RT OS's serial driver), but I just wanted to check with someone with more knowledge on the topic.

Thanks again!

[GPIB_Guru]

For example, RS232 uses two wires - one for TX and one for RX. Typical CAN uses differential signalling. You also need a CAN controller to generate the appropriate bit patterns on the bus. RS232 uses simple start bits, stop bits, and parity bits for error handling. CAN has CRCs and uses bitstuffing. CAN is also a multimaster bus meaning that it is a wired OR, vs RS232 that uses push-pull technology.

Sorry.

[dfjuggler]

Thanks again!