obdII bluetooth with CANCaseXL tool

Question

This is Kishore

I use ELM327 based OBDII to Bluetooth adapter to monitor the CAN traffic in the Passenger Vehicle. Said otherwise, our intent is to deploy EML327 as a CAN2BT Dongle (for CAN message Rx purposes).

I would love to use the Monitor All feature to receive all messages in the Vehicle (not just Diagnostics typically done over OBDII protocols). I intend to use AT-MR and AT-MT interfaces supported by ELM327 to selectively listen to messages our Application is interested in.

The issue I have is that in the Lab the ELM327 is hooked to a CANCaseXL and in AT-MA or AT-MR or AT-MT modes, the ELM327 does not send any acknowledgement. Because of this missing ACK, though the CANcaseXL is transmitting at compatible Baudrate, Transmit errors drive the CANcaseXL into Error state.

Is there a way to send a sequence of Proprietary AT commands to put the ELM327 into a mode where it is not communicating over OBDII Diagnostic protocols, instead listening to Raw CAN Bus activity with due ACKs?

Need communities kind help in this regards

Thanks and Regards Kishore

Answer 1

Try the CSMx command. See page 15 of the ELM327 datasheet:

CSM0 and CSM1 [CAN Silent Monitoring off or on ]

The ELM327 was designed to be comptetely silent shile monitoring a CAN bus. Because of this, it is able to report exactly what it sees, without colouring the information in any way. Occasionally (when bench testing, or when connecting to a dedicated CAN port), it may be preferred that the ELM327 dows not operate silently (ie generates ACK bits, etc.), and this is what the CSM command is for. CSM1 turns iton, CSM0 turns it off, and thedefault value is determined by PP 21. Be careful when experimenting with this, If you should choose the wrong baud rate then monitor the CAN bus with the silent monitoring off, you will disturb the flow of data. Always keep the silent monitoring on until you are certain that you have chosen the correct baud rate.