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Bus utilization of XC4x modules in MC43 & MD5 system
We are planning on having 1 x MC43FS M24 with a single expansion bus loaded with 5 x XC43 modules. All the IO on each module is not used but it would be nice to have them all the same modules for consistency throughout the system. Is there any concerns with bandwidth with 5 modules on a single bus or is it worth cutting as many down to the smaller XC42 or XC41 where possible? They may have lower bus utilisation with the smaller variants?
Are all the 5 x busses on the MC43 range the same throughput? (MD4 for example had faster busses on A and B I think).
We are planning on 6 x MD5 connected to the MC43, and I have reservations about bandwidth also on the master and diagnostics bus.
Is CAN FD coming soon? hopefully this will ease my concerns as there is not any real way of calculating bus loads, only measure when the system is complete?
Customer support service by UserEcho
Hi Kevin,
XC43 modules are relatively “quiet” on the CAN bus since they mainly respond to polling or commands from the master. If not all I/O is used, bandwidth load stays low, even with 5 modules. I do not think you would see that much difference using XC41/42 modules.
MC43 5 X CAN-BUS are all the same speed/priority. To my knowledge, there is no speed tiering like on MD4 A/B BUS.
I would Keep MD5's on a dedicated bus. Use separate bus for diagnostics. Separate bus for I/O modules.
As for CAN FD, it would be a game changer!
Sounds like a fun project.
Thanks for the information.
I currently have master bus (with 6 x MD5 and 1 x MC43), diagnostic bus (connecting all masters) and expansion bus (with 5 x XC43) off the MC43. Each bus is independent and not shared, so hopefully this is the most efficient way.
The displays are showing information from the MC43, mainly data values in the logic and providing some virtual inputs into the control system. 6 displays and 1 MC43 seemed to be quite a high module count on a single bus (master and diagnostic), but we have never had this quantity hooked up before and I was unsure on bus loading and whether I should be concerned.
It sounds as though the XC43 modules should be fine off one single bus on the MC43 at least!
Yes, CAN FD on Diagnostics bus is coming soon.
Some discussion on this here: CAN-FD / Software / IQAN
On the MC43, use CAN-A to CAN-C for diagnostics to be able to upgrade to CAN FD when that comes.
Thanks for the info. Is this the same for the busses on the new M24 modules?
Yes, the CAN controllers are the same in MC4x-M24.
What -M24 has as an advantage is better CAN transceivers with SiC, this improve the robustness of the bus. Useful when running higher bitrates.