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Measuring CAN bus
The CAN bus is easily checked at each pc-board by measuring the resistance value between CAN-low and
CAN-high against GND (ground). Before measuring, disconnect the pc-board completely from the machine.
If the measuring result is too low (1k ohm or lower), the CAN controller chip is damaged and the pc-board must be
exchanged.
Measuring the CAN bus at the MAPRO
Result: about 60k ohm each
CAN_LOW
GNDCAN_HIGH
Measuring the CAN bus at the front panel
Result: 50k ohm - 60k ohm each
Measuring the CAN bus at the DMR-RT3
Result: about 490k ohm each
CAN_LOWGND
CAN_HIGH
Measuring the CAN bus at the DMRPP05 (Push-Pull DMR) is di󰀨erent, there the result is about 0.9k
ohm by standard. A faulty CAN controller chip may not be directly detecable.
Since week12 2017, CAN controllers with a higher dielectric strength are used on all pc-boards.
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