The CAN bus tester 2 causes a beat of the bus or a humming at 50 Hz (60 Hz where this mains frequency is used) when using the supplied power supply.
The problem is design-related, affects all switched-mode power supplies and is determined by the parasitic coupling capacitance between the primary and secondary sides. This imposes a slight hum on the bus. Depending on how many participants there are on the bus and how their inputs are connected, the phenomenon is more or less strong.
Usually this does not lead to any problems on the bus. Only very few participants with a high potential difference is a disturbance theoretically possible.
- If your bus carries a CAN supply voltage, try powering the tester out of the bus and not using the power supply. The tester works with bus voltages from 9V.
- Supply the tester from a battery, battery pack or, for example, from a power bank for laptops (one USB port is not enough).
- Bring the mass side of the power supply to the potential of your bus. An adapter piece is needed or you open the DC line or DC plug of the power supply.
A supply voltage of 24V is required for the wiring test. Please note this during battery operation.
50 Hz hum (float) superimposed CAN telegrams
Operation with ground bridge to bus potential
Operation with battery pack