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.
