I can wire any device onto the CANBUS, as long as the the “branches” are kept short and I have 120 ohms at each end.
This being said, I see that the OrangeCube already has a 120 ohms terminating resistor to its CANBUS port. Therefor, I can only put the Flight Controller (FC) at of the end of the CANBUS loop.
Am I right in this train of thoughts, am I bound to only put the FC to one end of the CANBUS?
And what would happened if it is in the middle, so I can send the CAN one side to the front and one to the back of my plane.
@Kojoe what is the length of wires from Cube to the Nodes? Please note that with bitrate of 1Mbit/s stub length can be upto 30cm safely meaning you can have one of the two nodes terminated, as long as your nodes are within this distance from the Cube. If that’s not the case, best recommendation is to add terminators on both end of 240Ohms on each end. Ensure that total resistance on the bus stays between 60-100 Ohms, i.e. either two 120Ohms in parallel, or one 120Ohm (on Cube) and two 240Ohm in parallel and so on.
There will be about 12 to 15 devices connected to the CAN. With an approximate length of 5m going forward and an other 10m going to the back.
It is good to know that I just need to keep the transmission line impedance to around 60 ohms.
I was also looking at removing the cube CAN resistor of 120 ohms, any thought on it?
@Kojoe you can’t remove/disable the 120Ohms without opening the CubeOrange case, which will be too invasive and possibly destructive. Best strategy would be to terminate using higher resistance on two ends as mentioned.
Also note that it may turn out that you don’t actually need terminating. If using latest Ardupilot firmware, there is a way to get CAN Stats to verify CAN Bus health, you can use that as well. ArduPilot File Systems — Dev documentation@SYS/can0_stats.txt or @SYS/can1_stats.txt