How much USB CAN/LIN/DAQ traffic can a single USB 2.0 port

[rory_gc]

Hi, My first post on the LABVIEW forum. I have to validate the feasability of a labview based solution before the piggy bank can be open.

I'm relatively new to CAN/LIN in the LABVIEW environment as I have traditionally used Vector CANoe solutions exclusiveley in automotive product development.

I would like to develop LAVIEW stand alone application based test kits for CAN, LIN and Hardwired Products.

This will require 1 X CAN, 2 X LIN and 1 X DAQ.

My question is....If I put these all on a single USB hub, will the throughput of the USB port/LABVIEW drivers be sufficient to allow me to emulate 2 master LIN nodes and 1 CAN ECU node whilst reading data from the DAQ.

Also, I have no intentions of developing a RTOS based system so am I correct in thinking that I don't need the Real Time LABVIEW. The emulators do not need to be perfect, just good enough to send data requests and reat the responses off the Buses.

Thanks for any help you can provide. 

[GPIB_Guru]

Well, the CAN bus is ~1Mbit bus at the fastest. Assuming a 100% overhead from NI-CAN (which is overdoing it, but this is an example scenario), it would consume ~2Mbits/s of the USB.

LIN is a 20k/s bus, so that is generally irrelevant, but if you assumed the same 2Mb/s for each port (again, way overdoing it), you would be at a total of 6Mb/s for the CAN and LIN.

USB could probably provide 300Mb/s (really 480, but you don't ever get ideal and I am continuing my trend of 'worst-case'), so that CAN and LIN usage on the bus should be ~2%. Unless you are using a DAQ device that can consume 98% of the USB resources, I don't see any problem with this setup.