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SN65HVD1040 bus error

Other Parts Discussed in Thread: SN65HVD1040

I have 2 can boards with sn65hvd1040 transceiver. One board reads data from the sensors then it sends the data to another board via CAN, the other toggle the state of relays according to sensor data. For power supply a 12V-0-12V, 2A transformer is used.

I am not able to communicate as i get bus error. 

Voltages under recessive state( no communication)

1) Sensor Board 

CAN_H + GND = 3.02V, CAN_L + GND = 3.02V

2) Relay Board 

CAN_H + GND = 1.85V, CAN_L + GND = 1.85V

When i short grounds of both boards, Board 1 GND <---------------------> Board 2 GND , voltages on pin CAN_H = 2.45V, CAN_L = 2.45V on both boards, but still issue is not resolved.

Need some help to figure out the issue.

als2.pdf

  • Hi anishkumar,

    to help you, I would like to ask some questions about your setup:

    1. Have you checked the signal at the receiving node with a scope? Could you provide those scopeshots? They'll help us to understand what is going on on the bus.
    2. What kind of bus error do you get?
    3. How big are the Vcc voltages at the IC's? All 5 V? What do you see with a Multimeter?
    4. What bus speed are you using?
    5. Is there a specific reason that you use linear regulators? Depending on the loading your power supply might be wasting quite some energy.

    Best regards

    Till