Tuesday, July 11, 2017

CAN communication with Chevy Volt BMS Battery Energy Control Module

As detailed in the previous post, I have a Chevy volt battery in the rear of the 74 Bug in parallel with the OEM BMS hooked up. I am trying to verify that the BMS is working. The BMS has a CAN communication system. The X1 connector on the BECM Pin 3 WH/BK is CAN- and pin 4 L-BU is CAN+.
USB CAN device

I bought an USB CAN communication device from eBay to read the CAN data. It is called: "USB-CAN USB to CAN bus Converter Adapter For professional Notebook PC Laptop" for $21.49. It is labeled USB-CAN A1+. It has the following features:

  • A standard CAN interface, CAN-H and CAN-L two-wire interface;
  • Jumper selectable access or disconnect the terminals 120 ohm resistance;
  • The USB interface supports USB2.0, compatible with USB1.1;
  • Supports standard and extended frames;
  • Support shielding / filtering;
  • Support two-way transmission, CAN send, CAN receiver;
  • High-speed CAN transceiver the TJA1050; baud rate between 20Kbps-1Mbps optional;
  • USB interface directly powered, no external power supply;

Product link: USB-CAN USB to CAN bus Converter Adapter For professional Notebook PC Laptop

Software for Windows was available for download. It is in Chinese. The software is called "CAN bus debugging tools Ver 4.6". It detected the USB device on the appropriate COM port but I couldn't get it to read any data.

To be continued ...

Update:
I hooked it up and couldn't get it to work. Not sure if it is defective or if it is a software problem or if I hooked it up wrong.

1 comment:

  1. Btw, I also ordered such a USB CAN A1+ device.

    Take note, there are two manufacturers of this device. QM (http://www.qm999.cn - offline) and LMDZ (http://www.qhdlm.cn/ch/Product-36.html). You should see which one you have based on the logo on your device in the top left corner.

    My guess the QM is the older version/company, probably based on the TJA1050 can transceiver. The LMDZ (the one I have, with firmware version 1.11 - seen only with their debug software) contains a cp2102 USB-to-UART converter, some unbranded microprocessor and the MCP2515 can transceiver.

    I received my device without software and had to search all over. The "can bus debugging tools" software and DLL drivers look very similar between QM and LMDZ, but they are not compatible (probably due to the difference in CAN module).

    I've seen "can bus debugging tools v4.6" for the QM one, and "can bus debugging tools v5.0" for the LMDZ one. I got the latter via my supplier (which supposedly got it from LMDZ directly). You could try different versions from the www.wheelchairdriver.com forums as well as the waybackmachine (https://web.archive.org/web/20171108165535/http://www.qm999.cn/rj.html).

    Note both devices are probably using the cp2102 usb driver. This can be downloaded separately from silabs.com. The newest driver is 6.7.5 but I had a successful connection with the debug tools using driver v.6.

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