How to make 5 Mbps work? or how to change the "SSP offset" for PCAN-USB FD?

[ianasran]

Hi all,

I'd like to set up 5 Mbps on my USB FD, but could not make the communication work. My parameter settings are below.

SSP offset.png (63.58 KiB) Viewed 13626 times

CAN FD settings.png (135.81 KiB) Viewed 13626 times

I've read some articles that say changing the "secondary sample point offset", or SSP offset may work, but in PCAN-view this option is grey-out and I could not find a way to configure it.

Thank you.

[M.Heidemann]

Hello,

I'd like to set up 5 Mbps on my USB FD, but could not make the communication work

The communication to what exactly?

Especially with CAN-FD the bitrates need to be configured correctly for all nodes on the bus,
this includes the sampling point.

Can you describe us your setup in more detail?

Best Regards

Marvin

[M.Heidemann]

Hallo,

Any updates regarding this or was this resolved?

Best Regards

Marvin

[ianasran]

Hi Marvin,

Thank you for the follow up.
The topology now is just (PEAK PCAN-USB) -- (another CAN FD device)
I am checking if it's the problem of an unmatched sample point.

"Especially with CAN-FD the bitrates need to be configured correctly for all nodes on the bus,
this includes the sampling point."
For CAN FD data bit rate 5 Mbps I am using 75% sample point as the figure above, and checking the other device.
Just a check, is there a 'typical' or 'common' value for CAN FD data bit rate higher than 1 Mpbs?
Thank you.

Sincerely,
Tiffany

[M.Heidemann]

Hello,

Have a look at the predefined Bitrates in PCAN-View, they give an pretty good
idea on valid bitrate settings you would typically encounter.

Best Regards

Marvin

[KennyDemers]

I have the same question. What would the bit rate preset settings be to support 5Mbps? My clock frequency is 40 MHz and my desired Nominal Bit Rate is 1 Mbit/s and Data Bit Rate is 5Mbit/s.
I currently can transfer successfully at 1 MBit/s and 4 MBit/s but would like to transfer at our devices maximum speed. You supply default values for 2, 4, 8, and 10 MBit/s. Could you display 1 more default speed?

[M.Heidemann]

Hello,

Simply using defaults on a CAN-FD network will not be sufficent, you have to be particular about the config otherwise communication will not be established, CAN-FD is pretty strict and doesnt allow for much tolerance in bitrate settings.

The defaults we include are also more defaults in our own ecosystem, more than industry wide standards (exept for the SAE specified bitrates)

You can use the PEAK-Bitrate Calculation Tool, make sure the Sample-Point and bitrate-Speeds matches your bus:

https://www.peak-system.com/Bit-Rate-Ca ... .html?&L=1

The clock speed should not be a concern as long as you make sure bitrates and sample-point are correct.

BR

Marvin