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CAN BUS or SAEJ1939 communication for Vehicular applications

Question asked by peterfreedom on May 2, 2008
Latest reply on Jul 9, 2008 by rmarkley
I wanted to share my experience with my new MSO6014A with the MSO6000-AMS CAN BUS Trigger and decoding option.

I'm presently working on a Hybrid vehicle that use a IQAN Controller from Parker, 2 Electronic Drives with Motor/Generator, 3 Ni-MH Batteries, a Diesel Engine etc. All those equipment are talking on the same CAN Bus on a twisted pair cable.

I bought this scope thinking it could help troubleshoot the communication problems we had but it was more helpful than I thought. First, without even reading the manual I was able to understand how to setup the scope for CAN Signal and set the trigger on SOF (Start Of Frame). The scope will automatically recognize the start of a communication frame and show it on the screen. It will also decode the data and show it on the screen and tell you if the CRC or checksum is OK.

But when you have a lot of equipment sending messages it is hard to know if a particular one is sending the data it is supposed to. Not with this scope. Instead of triggering on SOF, you can set the trigger for a specific address (complete or partial) on the CAN Bus and the the scope will only trig on these message. If it is not triggering, then your equipment is not talking on the Network. Even better, you can set the trigger for an address AND a specific DATA (complete or partial). So if an equipment is sending a lot of information, you can pinpoint a particular information you are looking for. It is like being able to hear a particular sentence from one person in a place full of people all talking at the same time.

I would suggest to buy the Isolated differential probe because if you plug the scope with a regular probe and a Portable computer on an other equipment at the same time, you could have ground loops if you connect the portable computer to the AC outlet.