PEAK-System Forum

Below a short guidance to verify a defective CAN-highspeed transceiver (for example NXP82C251 or MAX3057ASA)

1. Start the computer and take care that the CAN-hardware is built-in or plugged in

2. Please take care that no CAN-application is running or using the PCAN-hardware (for example: the LED from the PCAN-USB adaptor must be ON and not flashing), otherwise please close the application

3. Disconnect the CAN-connector or CAN-cable physically from the module

4. Please measure with a multimeter (DC measurement area) the voltage the between pin 2 (CAN-L) and pin 3 (GND) from the 9 pole D-SUB. You should measure 2.5V +/- 0.2V

5. Now measure the voltage between pin 7 (CAN-H) and pin 3 (GND) from the 9 pole D-SUB, you should also measure 2.5V +/- 0.2V

6. If you measure other voltages then it looks that the CAN-transceiver is defective (through overvoltage or static electricity charge)

Note: This is only a quick check

Would the over-voltage have to come from the module side or from the USB? we just had this happen and trying to determine the cause so we can implement some preventative measures. Thanks!

As we talk about the CAN Transceiver (see Post Headline) it is a over voltage from the CAN Lines.
See Data Sheet of the used CAN Transceiver - they could handle Voltage Levels over the CAN specification (ISO 11898-1) without any problems - but also this have limits!
Most problem is that customers "plug & play" CAN Networks while Network is running, or have different GND Levels etc.
Cross flows can very quickly lead to problems here.