How to get the current time on CAN Tx to calculate Rx response timing

[sveinse]

I'm interested in capturing the response time on CAN bus requests. The Rx frames have timestamp attributes, but the Tx frames my code generates does not have a timestamp. Is there a way to set the current time when the Tx message was sent? Alternatively, is there a get_current_time() function that can be called to fetch the time (which is using the same epoch and time mechanisms as the receivers)?

I'm on Windows using PCAN.

[zariiii9003]

Did you instantiate the PcanBus with receive_own_messages=True? I'm not sure how the PCAN API handles this, but i think the recv() method should return your Tx messages with a timestamp.

[sveinse]

I'm not getting the responses back with receive_own_messages=True with the PCAN I have. I looked into the pcan code, and it seems the setting have a operation against the PCAN driver, but it evidently doesn't do anything.

[zariiii9003]

According to PCAN docs, setting PCAN_ALLOW_ECHO_FRAMES to PCAN_PARAMETER_ON should be sufficient.

Maybe it's not supported by your device or driver version?

[sveinse]

I tried using datetime.now().timestamp() to set my own timestamp on Tx, but I get 1.3 second offset from the true values as measured by HW trace. Without a way to set .timestamp on Tx messages or to read the current timestamp from the PCAN driver, I don't think I'm able to use the .timestamp field in the Rx messages.

[sveinse]

It turns out had a simple typo throughout the code: receive_own_message = True. Unfortunately python-can doesn't disagree with using that, except it doesn't work obviously. So I ended up with receiving my own messages to retrieve its timestamp which works perfectly. Closing the discussion.