RollerCAN and CAN bus termination resistsance
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Hi,
Is there a 120 Ohm resistor across the CAN High and CAN Low lines in the RollerCAN? and can it be disabled?
I have four of these connected to the same CAN bus, and am measuring a buss resistance to below 30 Ohms, so it appears that each unit is loading down the buss.
As you probably know, there is only meant to be a 120 ohm buss termination resistor on the ends of the buss, so two of them, which gives a buss resistance of 60 ohms.
The 30 ohms I'm getting is really stuffing up the CAN communication...
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Hello @NickMaddock
please have a look at the schematics (top right corner). To me the 120 ohm resistor R16 looks permanent and I can see no switch to disable it.
Thanks
Felix -
Hi,
Yeah I guess I'm in disbelief, or maybe hoping it is a mistake. Seems a bit odd to design something that is meant to work on a CAN bus and then stop it from working as a bus.
Suppose my only option is to open it up and try to remove the termination resistor.
I could use the I2C bus, but I see they have put pull ups in to break that bus as well.
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@NickMaddock Howdy. I know this thread is old, but I just got a couple of these units thinking they would not be hard-wired terminated, too. I guess the lesson for me is to read the schematic even when it seems apparent that you would not want these always to be terminated on each unit.
Were you able to find a way to make these work how you wanted? I noticed in the demo video that you could have more than two devices hooked up and that they have two rollercan units connected to an M5Stack Core. Since there is no other documentation, I am assuming that the Core is not terminated, and thus, the three devices shown in the demo video would work together with no issues.
Unless there is an easy way to hook these up non-restrictively, I am glad I did not buy more than two. The motors seem nice in every other way,
