How to use esp32 to decoder BMS Jikong BD6A20S8P

[NguyenHau101202]

hello everyone, i';m a newbie, i have a project about use ESp32 read the data of BMS Jikong through RS485 protocol. but i don't have any reference document about frame data structure of it. Can someone share it with me ? Thanks

[meccip]

i think all info about protocol is in the docs folder in code source https://github.com/syssi/esphome-jk-bms/tree/main/docs

[NguyenHau101202]

i saw 2 file : RS485 English Obsolete and RS485 communication example. can someone tell me the different of both file. because the data frame structure of 2 file is different. i don't know which one to use

[meccip]

but what do you want to do ?

[syssi]

I depends. ;-) If you set the UART protocol to 4G-GPS Remote at the JK-BMS app this YAML should be able to talk to the BMS: https://github.com/syssi/esphome-jk-bms/blob/main/esp32-example.yaml

If you set the UART protocol to JK BMS RS485 Modbus this YAML / protocol description should apply: https://github.com/syssi/esphome-jk-bms/pull/409/files

You could also communicate using bluetooth with your BMS (this requires a ESP32): https://github.com/syssi/esphome-jk-bms/blob/main/esp32-ble-example.yaml

[meccip]

hi @syssi can you help me with some info ? i want to get max/min cell number from bms with mod bus https://github.com/syssi/esphome-jk-bms/pull/409/files#diff-af9279656260549e78da3780c089c1e1adc3a34a19220f0e86e3f7a6c32412e6
There are at the same address. Can you help me ?

0x1248 72 UINT8/UINT8 2 R MaxVolCellNbr / MinVolCellNbr

• platform: modbus_controller
  modbus_controller_id: bms0
  name: "${name} max voltage cell"
  address: 0x1248
  register_type: holding
  value_type: U_WORD ??????
  unit_of_measurement: "V"
  device_class: voltage
  state_class: measurement
  accuracy_decimals: 0

[syssi]

@meccip You have to extract the hi/lo byte using a bitmask. Could you create another discussion to address this task and describe your setup? Thanks in advance.

[NguyenHau101202]

i use esp32 to read the data of bms and export it TFT display. i wanna decode the data rs485

[NguyenHau101202]

Can someone tell me the difference of 2 file : RS485 English Obsolete and RS485 communication example ? please!

[syssi]

The RS485-english-OBSOLETE.pdf is a protocol description of a firmware version / BMS models from many years ago. This protocol doesn't apply anymore and can be ignored.

The RS485 Communication example.pdf is an example request/response (cell info frame) of the 4G-GPS Remote protocol.

[syssi]

You should focus on this protocol description: https://github.com/syssi/esphome-jk-bms/blob/add-jk-pbx-support/docs/pb2a16s20p/JK_BMS.RS485.Modbus.v1_0.pdf

A first draft of the implementation is available here: https://github.com/syssi/esphome-jk-bms/blob/add-jk-pbx-support/esp32-jk-pb-modbus-example.yaml

[NguyenHau101202]

may i ask whether BMS RS485 Modbus v1 document also use for BMS jikong bd6a20s8p ?

[NguyenHau101202]

Is this file also use for jk BD6A20S8P ?

[NguyenHau101202]

Yeah, but i wanna build DIY decoder, with TFT display. I build base on adruino platform iíntead of esphome.

[syssi]

Again: These are the protocol details you are looking for: https://github.com/syssi/esphome-jk-bms/blob/main/docs/protocol-design.md

[NguyenHau101202]

I just build a program to read data of bms. I added a module rs485 ttl. But, i upload the code, the tx led in rs485 ttl is blink, the rx led is not. Nothing response. Help me

[syssi]

You could use this project to verify your wiring and to make sure your BMS is able to respond to valid requests.

[meccip]

i use the same rs ttl board. I can say that there is a possibility that the board is broken. I really experienced this, only one led worked. I changed the board and it worked. Or if the right protocol is not selected into the bms, the led will blink the same.