Connection To BMS Failed

Connection Failed

There are a number of reasons why the connection might fail. The common ones are:

Please attempt the following steps before contacting us for support.

  1. Ensure the BMS is powered when connecting to the BMS.. The BMS requires external power to respond to the communication. At a minimum, +12V must be applied either Main I/O connector pin 2 (Blue / READY mode power) or Main I/O pin 3 (Red / CHARGE mode power). Pin 12 (or 11) must be connected to the power supply?s negative. The main I/O connector can be unplugged from the unit and a multimeter used to verify the power source. The power supply should also be checked when the unit is powered since it is possible that a connection is high resistance and there is a voltage drop causing the BMS not to receive full power. Additionally, the current draw can be checked to verify that the BMS is operating by measuring the current used by the BMS. It should be over 150mA and below 300mA. Revision D hardware and newer has a +12v signal output on the Main I/O connector pin 14 which is useful for verifying that the BMS is properly powered since it also verifies one of the internal power supplies is working.

  2. Verify the correct baud rate is selected. The Orion BMS and CANdapter can operate at various baud rates including 125kBps, 250kBps, 500kBps and 1000kBps. The baud rate of the CANdapter and the BMS must match for successful communcation. The BMS units are shipped operating at 500Kbps by default, however the baud rate setting on the BMS can be changed. Important: All devices on a CANBUS MUST communicate at the same baud rate. If any two devices on the CANBUS communicate at different speeds, the bus will become garbled and completely unusable for all devices on the bus. For this reason, the Orion BMS has 2 separate CAN interfaces which can be configured at different baud-rates from each other so it can interface with devices operating at different baud-rates.

  3. Ensure proper wiring of the CAN bus, including proper termination of the network. The majority of the problems with CAN communication turn out to be wiring issues on the CANBUS, many of which visually appear to be correct. First, verify CAN H and CAN L are not backwards. To verify correct connection (with the CAN1 interface, substitute pin numbers on the BMS for CAN2), with both the DB9 connector and the OrionBMS Main I/O connector disconnected, use a continuity tester to ensure that pin 3 on the DB9 connects to pin 18 (or pin 21 on CAN2) on the Main I/O connector and pin 5 on the DB9 connects to 19 (or pin 20 on CAN2) on the BMS connector. Test on the mating side of the connectors for best results. If continuity is good, with the Main I/O connector from the Orion BMS unit still disconnected test the resistance from pin 3 to pin 5 on the DB9. It should read approximately 120 ohms if one of the termination resistors is located inside the BMS (CAN1 has an internally loaded 120 Ohm resistor, CAN2 does not). Then with the Orion BMS power off, connect the Main I/O connector to the Orion BMS and test resistance again. It should drop to 60 ohms. If the resistance measured with everything connected (but powered off) does not read approximately 60 Ohms then there is a problem with the termination of the network.
    The physical layout of a CAN bus also matters. Ensure that taps off the main trunk of the bus are kept 4ft or less (see the wiring manual for more information about CAN bus wiring.) Note that the Orion BMS ships standard with a termination resistor on the CAN1 interface and without a termination resistor on the CAN 2 interface. Special order units may be configured differently. Important: Exactly one CAN 120 ohm termination resistor MUST be at both physical ends of the bus to work properly (total of two resistors)! We receive many inquiries from customers who assume it will work properly without resistors or work with only one and find that they are unable to communicate with the BMS. If you only have one termination resistor, please add proper termination before inquiring for help as this solves the majority of communication issues.

  4. Check the status of the LEDs on the CANdapter. If the red LED comes on and stays on when trying to connect there are errors present on the CAN bus which can indicate that either CAN high and CAN low may be backwards, the bus may be shorted (CAN-H and CAN-L are touching), there may be devices operating at different CAN frequencies, or there could be be improper termination on the network. If the CANdapter LEDs don't come on first verify that the CANdapter is properly connected. The green and red LEDs should flash 3 times quickly when the CANdapter is first connected to the computer.

  5. Remove all other devices from the CAN bus and attempt to communicate only with the Orion BMS or switch to the other CAN interface on the Orion BMS to attempt communication. This ensures that only the BMS is connected to the CAN which rules out any other devices interferring with the communication (incorrect baud-rate, etc). Also Make sure that the CAN termination resistors are in the proper locations (repeat step 4.)

  6. Restart the application and power cycle the BMS (remove all power from the BMS for > 45 seconds) and try again. Please note that new hardware versions of the Orion BMS are now able to remain alive in low power sleep for up to 30 seconds and actually require power disconnected for at least that length of time.

< Appendix A: Troubleshooting Utility ConnectionNo CANdapter Found (None Found) >