I am trying to debug a CAN network with the NI-CAN. However, the setup for the microcontrollers that are on the network is different than the NI-CAN. I will explain
With the NI-CAN Setup, I can choose to set the following:
Baud Rate Prescaler
Synch Jump Width (SJW)
Time Before Sample (TSEG1)
Time After Sample(TSEG2)
Sample Mode
With the Microcontrollers, the setup was done with the same settings, but also includes a propagation delay (PRD) which per the manfuctures instructions, comes after the SJW, before TSEG1. The microcontrollers documentation shows that the total bit time is therefore a sum of SJW, PRD, TSEG1, TSEG2). So the question is. If the microcontrollers are set to:
BRP = 4
this would make Tq = 5.51us
SJW = 2
PRD = 3
TSEG1 = 3
TSEG2 = 4
this would make K = 2+3+3+4 = 12 Tq
So the baudrate would be: 1/(K*Tq), or in this case 15.124kbps
If i do the same with NI CAN, Setting the Tq to 5.5 using BRP, BRP becomes 44, then set SJW = 2, TSEG1 = 3 (TSEG1+1 = 4), TSEG2 = 4 (TSEG2+1 = 5), the baud rate becomes 18.182. so now i have two choices, ignore the Bit Timing, or ignore the baud rate. I have tried both, but I only get error messages.
The network is working. It just has some bugs that I need to see the messages to fix.
The term resistors are 120 ohm
The Bus length is about 20ft
Thanks for any help, i hope i have given enough information
