MoTeC Global Forum

Hi All
Is there a limit to the number of connections to the CAN?
If i have A m800, SDL3, DBW4, 2 x IRN4 C (CAN temp sensors), SLM, PDM 15, BR2, CDI 8.
Thats 9
Could thay all be hooked up to One CAN?
Could the Two Temp sensors go on the SDL3's second CAN?
Thanks

Not a problem - the SDL3 has 20 CAN channels which can be split between CAN-Bus 0 and CAN-Bus 1.

Personally I would put the devices critical to the engine running on one CAN-bus and put the others (like your IRN4) on the other bus.

Also, check the address of the devices you are connecting. Most of the Motec gear should be okay, but be careful with the Texense as they do use some of the same addresses at Motec.

Thanks MSE
That's good to hear I read something that got me concerned that there was a limit of 6.
Is there a difference between CAN Bus 0 and CAN Bus 1
Does the SDL3 have a different Address on each of the CAN Bus

Any thoughts on dividing up The Bus 1 & 2
On CAN-Bus 0. M800, DBW4, PDM 15, SLM,
and
On CAN-Bus 1. 4 x IRN4 C , BR2, CDI 8
Thanks

When dividing up a CAN bus, there are 2 main things to consider, Load, and reliability.

I would consider this.

1) Reliability. If you have some items that are essential to keeping the car running, whilst having others that are less important, I would divide them us that way. So.....

CAN bus 0 M800, PDM, DBW4, CDI8
CAN bus 1 SLM, 4 X IRN4, BR2

this way, if any of the IRN4's have a problem and crash the bus, the car will continue to run. If you put the CDI8 on there, and it required the CAN bus to run, the car would stop. Reliability should be first consideration.

2) load. It is important if you have lots of traffic to share the bus loads. You dont want one unloaded CAN bus, and one that is empty. We have seen cars where one BUS is full, to the point of having dropouts whilst the other bus is not even used.

So, first priority is reliability, second is sharing the bus loads.

regards,

Jamie