PCAN-View weird transmit issue

[ChiefSleepyEye]

I am using PCAN-View with a USB - CAN-FD device and have a weird transmit issue.

I've created a message to transmit at 1M arbitration/4M data bit rates.
The LED on the CAN-FD device is flashing green and status at the bottom of the PCAN-View window shows "OK".

When I click "Send" nothing happens but the LED changes to red and the status at the bottom PCAN-View says "Error..." and Warning and nothing is received by the CAN-FD device the Peak device is connected to.

Now here's the weird part. As soon as I click "Disconnect" OR exit PCAN-View, the remote device receives the message and everything about it is received correctly. Termination is enabled in the Peak CAN-FD device and at the other end.

I've tried using slower arbitration/data bit rate pairs as well as normal CAN mode with no switching of the data rate. All behave the same way.

Host machine for the device and PCAN-View is an INTEL processor based PC running WIndows 10. Thanks for any help anyone can provide.

[M.Heidemann]

Hello,

To assess this issue, please try the following:

Make sure that with your devices both CAN-FD Timings match exactly.

Make sure both device use the same BRP, TSEG1, TSEG2, SJW and are operating at the same sample point, both for Nominal and Data-phases.

CAN-FD is dependent on both devices having the exact same CAN-timing to work properly.

Please report back to me, if this has resolved the issue.

Best Regards

Marvin

[ChiefSleepyEye]

I double checked and clock frequency (20Mhz), TSEG1, TSEG2, BRP, and SRJ for both arbitration and data bit rates for both ends and they are identical. As I stated, nothing is transmitted on the wire at all by the Peak device when I click "Send". But when I click "Disconnect" after clicking "Send", the message is sent on the wire and the remote end receives it without error. The only two devices on the bus are the Peak device and the device receiving the message. The fact that when the message is actually sent on the wire the remote end receives the message without issue suggests that the bit timings are correct. The main issue to me is the fact that clicking "Send" doesn't cause anything to be sent on the wire until I click "Disconnect". The arbitration and data rates I'm using are 1M/4M.

[M.Heidemann]

Hello,

to assess the issue further, please provide the following information:

- Which firmware does your PCAN-USB FD use?

- Which Version of PCAN-View do you use?

- Which version of our Peak OEM driver is intalled?

- What happens if you send a regular CAN 2.0 frames?

- Can you create a trace of both this CAN FD frame and the regular CAN 2.0 frame?
Make sure you have all errors turned on for your trace:

PCAN-View_Trace_Error_settings.PNG (7.56 KiB) Viewed 8911 times

What errors can you see?

- Do you run your PCAN-USB FD off of a USB-hub or USB-extension?

- Can you measure the resitance on your bus between CAN-High and CAN-Low? Whats the measurement?


Best Regards

Marvin

[ChiefSleepyEye]

Enabling the trace shows bunches of

Other Error, Tx, Acknowledge slot, RxErr=0, TxErr=XXX

Does that mean the Peak USB-CANFD device is detecting an issue with the ACK sent back from the remote CAN-FD device? If so, what is the scope of issues that could be responsible for that sort of issue? Thanks for any info you can provide.

[ChiefSleepyEye]

I've been doing a bit of research on this and as I understand it the "acknowledge slot" issue means the transmitting end did not "see" the dominant ACK bit. When that happens the transmit end begins retrying the transmit forever until an ACK is detected. Is my understanding of this correct?

Looking at the code on the receiver side explains the behavior I'm seeing on that end. While I've done a bit of research on the issue nothing I've run across suggests causes of the issue. As far as I can tell it could be either configuration or physical issue(s)? Since the rx side does receive the message correctly I'm leaning toward a physical issue with the connection from the remote CAN-FD TX connection to the Peak Device RX? At this point I think I need to hang a scope on the TX and RX lines and see if something bad is going on. Thanks for the help you've given. Please let me know if the statements made in the first paragraph are correct.

[M.Heidemann]

Hello,

In this case the sent out frames are not properly acknowledged.

This could be due to a physical issue on your CAN-bus, like you have mentioned (Inproper termiantion, mismatching bitrates, loose cables..).

Also a common cause for this is a receiving node is in Listen-Only mode, the catch here is that a CAN-Node in listen-only will not send anything to the bus, not even acknowledgements.

My guess is that the termination is off, please see the last point of my previous post.

You should see about 60Ohms ( +/- 3 Ohms) between CAN-High and CAN-Low if the bus is properly terminated.

Please report back to me, once you have checked your physical connection.

Best Regards

Marvin

[ChiefSleepyEye]

The mention of listen mode only was the bit I needed. The code on the receiving end was written by me and when I looked at it I found that it was only enabling normal mode if there were messages to transmit from it's side. I changed the code to enable normal mode (non-listen mode) and now everything is working the way it's supposed to. E.G. After clicking "Send" in PCAN-View the status remains green "OK" and the data is immediately seen on the remote end. Also additional messages can be sent via PCAN-View without having to "Disconnect" first. Thanks for all of your help.

[M.Heidemann]

Hello!

Thank you for letting us know!

We are glad that you were able to resolve your issue.

Best Regards

Marvin

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