/esphome_sacredsun_rs485

ESPHome device to fetch data from LiFePo4 SacredSun SCIFP48100 (Tian BMS) or equivalent via RS485 and push to Home Assistant Entities

Primary LanguageC++

esphome_sacredsun_rs485

ESPHome device to fetch data from LiFePo4 SacredSun SCIFP48100 (Tian BMS) or equivalent via RS485 and push to Home Assistant Entities

RS-485

  • Pin 1 is RS-485 B-
  • Pin 2 is RS-485 A+
  • Each DIP switch represents a bit in the slave ID value
    • address 1: ON-OFF-OFF-OFF-OFF-OFF
    • address 2: OFF-ON-OFF-OFF-OFF-OFF
    • address 3: ON-ON-OFF-OFF-OFF-OFF
  • 9600 baud
  • ASCII
  • 8N1

ESPHome Hardware

You will need

  • any ESP32 or ESP8266 with 2 GPIOs for the serial Tx/Rx.
  • a RS-485 to UART TTL adapter board.

Frame decoding (development only)

For ESPHome usage you do not need to continue to this section.

Data mapping by looking at the comms with Tian_Power Energy Storage BMS V1.5.68-15.exe.

Command

The command must be sent in ASCII format.

  • Address 1: "~22014A42E00201FD28\r"
  • Address 2: "~22024A42E00201FD27\r"

Captured Sample Frame Response

The response is received in ASCII format.

~22014A0020C2002
01C138A0F0D070D0
70D070D070D080D0
70D070D070D070D0
70D070D070D070D0
70D0701360136013
6040140013601360
1360000000000640
1275C205B0026000
0000000000000102
3000000000000000
0000000000000000
000000000000000D
6B8.

Data Interpretation
Len Idx Values
1 0 Start Frame: “~” exclude from checksum
2 1 ? Always 22h
2 3 Pack number: 01
2 5 ? Always 74 => 4A
4 7 ? Always 32 => 0020
2 11 Frame Length before checksum: 194 => C2
2 13 ? Always 0 => 00
4 15 SOC %: 82.20 => 201c multiply 0.01
4 19 Voltage: 50.02 => 138A multiply 0.01
2 23 Number of cells: 15 => 0F
4*15 25 Vol xx : 33.35 => 0D07 multiply 0.001
4*3 85 xx_Temp : 31.0 => 0136 multiply 0.01
2 97 Number of temp sensors: 04
4*4 99 Temp xx: 31.0 => 0136 multiply 0.1
4 115 Current: 00.00 => 0000 multiply 0.01
4 119 ? Always => 0000
4 123 SOH %: 100 => 0064h
2 127 ? Always 1 => 01h
4 129 NominalCap 100.76 => 275C multiply 0.01
4 133 RemainCap: 82.83 => 205B multiply 0.01
4 137 Cycles: 38 => 0026
4*4 141 ? 0000 0000 0000 0000
4 157 ? Always 4143 => 1023h
4*11 161 ? 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
2 205 ? 00
2 207 Ending: D4 to D6 exclude from checksum
2 209 Checksum: B8
1 211 End Frame “.” is 0x0D

Checksum : CheckSum8 2s Complement, 0x100 - Sum Of ASCII Bytes, exclude start “~” and ending “D4 to D6”.

Todo

Still remaining is the decoding of the following

  1. Alarm
  2. Protection
  3. Fault
  4. Statuses: CHG, DSG, Limit, LED, Buzz, Heat