CAN bus issue for 200 meters cable

[aaronlee]

Hi,

We use 10 boards(S12ZVCA) to send CAN message every 10 seconds. And 1 board(S12ZVCA) to collect those CAN message.

It can work fine in 10 meters cable. But it is unstable in 200 meters cable. How to solve the issue? Do you have any recommend?

Slew rate: 4

Baud rate: 250kbps

Time segment 1: 4 (We will try "12" on next Monday)

Time segment 2: 1

RSJ: 1

Sample per bit: 3 samples

BR, Aaron

[lama]

Hi,

The long transmission line has its own distributed parameters. They creates reactance which depends on frequency. Moreover, they deforms edges of signals.

So you can solve your issue:

Decrease bitrate

Do correct bitrate calculations including real propagation delays ( https://www.nxp.com/docs/en/application-note/AN1798.pdf )

Use wires with low R/L/C parameters.

Use some repeaters.

Wireless CAN

For this distance probably you could use RS485 and UART.

Best regards,

Ladislav

[aaronlee · Accepted solution]

Hi Ladislav,

Thanks for your reply.

We only change Time segment 1 from 4 to 12. It can work stable in 200 meters cable.

The parameter as follow:

Slew rate: 4

Baud rate: 250kbps

Time segment 1: 12

Time segment 2: 1

RSJ: 1

Sample per bit: 3 samples

BR, Aaron