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6.2 Modbus protocol

Version 1.1 by Admin on 2024/12/05 17:26

Communication protocols

Modbus protocol

General information

The BMS Main 3 device provides information about the battery system using Modbus protocol. The BMS is a Modbus-server and it responds to the Modbus-client’s commands.

Interaction with the device is performed over the RS-485 bus (Modbus RTU) or the Ethernet network (Modbus TCP).

The RS-485 bus connection parameters:

  • baud rate, bps — 600, 1200, 2400, 4800, 9600 (by default), 19200, 38400, 57600, 115200;
  • word length, bits — 8;
  • parity — none;
  • device address (by default) — 32.

Ethernet connection parameters:

  • port — 502.

There is a description of the Input и Holding registers below. Column "Type" contains method of parameter coding:

  • U8 — unsigned 8-bit integer number;
  • U16 — unsigned 16-bit integer number;
  • S16 — signed 16-bit integer number;
  • U32 — unsigned 32-bit integer number;
  • REAL32 — single precision floating point number (IEEE 754 standard);
  • U8[x] — array of unsigned 8-bit integer numbers having a length of x;
  • U16[x] — array of unsigned 16-bit integer numbers having a length of x;
  • REAL32[x] — array of single precision floating point numbers having a length of x.

The bytes order of the word is little endian.

Input registers

Register addressNumber of registersContentType
0x00001

Hardware version:

byte 0 — minor;

byte 1 — major.

U8[2]
0x0001-0x00022

Firmware version:

byte 0 — patch;

byte 1 — minor;

byte 2 — major;

byte 3 — not used (set to 0).

U8[4]
0x0003-0x00042

Bootloader (ubl) version:

byte 0 — patch;

byte 1 — minor;

byte 2 — major;

byte 3 — not used (set to 0).

U8[4]
0x20001

Discrete input signals 1 (bitfield):

bit 0 — signal "Battery cover";

bit 1 — signal "Charger connected";

bit 2 — signal "Power up/down request";

bit 3 — signal "Inhibit charging";

bit 4 — signal "Inhibit discharging";

bit 5 — signal “CH contactor feedback”;

bit 6 — signal “DCH contactor feedback”;

bit 7 — signal “Insulation status”;

bit 8 — signal “Charge request”;

bit 9 — signal “Precharge request”;

bit 10 — signal “Discharge request”;

bit 11 — signal “PCH contactor feedback”;

bit 12 — signal “CH/DCH contactor feedback”;

bit 13 — signal “Main contactor feedback”;

bit 14 — signal “Interlock”;

bit 15 — signal “Fuse 1”.

U16
0x2001-0x20022Current (sensor 1, high range), АREAL32
0x2003-0x20042Temperature (sensor 1), °CREAL32
0x2005-0x20062Humidity, RH%REAL32
0x2007-0x20082

Errors 1 (bitfield):

bit 0 — error "Overcurrent";

bit 1 — error "Undervoltage";

bit 2 — error "Overvoltage";

bit 3 — error "Low temperature (DCH)";

bit 4 — error "High temperature (DCH)";

bit 5 — error "Battery cover";

bit 6 — error "High humidity";

bit 7 — error "Water";

bit 8 — error "Logic high temperature";

bit 9 — error "Logic offline";

bit 10 — "Critical error";

bit 11 — "Crown error";

bit 12 — "Cell count error";

bit 13 — error "HYG offline";

bit 14 — reserved (set to 0);

bit 15 — error "Combilift offline";

bit 16 — error "Short circuit";

bit 17 — error "High contactor temperature";

bit 18 — "Logic count error";

bit 19 — "ADC error";

bit 20 — “Current sensor error”;

bit 21 — “CH contactor cycles error”;

bit 22 — “DCH contactor cycles error”;

bit 23 — error "Shunt offline";

bit 24 — “Shunt error”;

bit 25 — reserved (set to 0);

bit 26 — error “WDT reset”;

bit 27 — error "No temperature sensors";

bit 28 — error "Temperature sensor shorted";

bit 29 — error “Spirit offline”;

bits 30-31 – not used.

U32
0x2009-0x200A2

Internal signals (bitfield):

bit 0 — signal "Low SOC";

bit 1 — signal "High charging current";

bit 2 — signal “Charging” (0 – open, 1 – closed);

bit 3 — signal "Allow charging" (0 – open, 1 – closed);

bit 4 — signal "Charging current present";

bit 5 — signal “Discharging” (0 – open, 1 – closed);

bit 6 — signal "Discharging current present";

bit 7 — signal "Voltage too high for charging";

bit 8 — signal "Heater" (0 – off, 1 – on);

bit 9 — signal "Cooler" (0 – off, 1 – on);

bit 10 — signal “Shutdown request (HYG/Spirit)”;

bit 11 — signal “Init” (current sensor calibration or BMS Logic scanning is performed);

bit 12 — signal “Precharging” (0 – open, 1 – closed);

bit 13 — signal “Shutdown request (Combilift)”;

bit 14 — signal "Cell analysis";

bit 15 — signal “Balancing 1”;

bit 16 — signal “Balancing 2”;

bit 17 — signal “Discharging (AUX)” (0 – open, 1 – closed);

bit 18 — signal “Power down ACK”;

bit 19 — signal “Crown EWS”;

bit 20 — signal “Main contactor” (0 – open, 1 – closed);

bit 21 — signal “Service reset”;

bit 22 — signal “Charging/Discharging” (0 – open, 1 – closed);

bit 23 — signal “Ready to charge”;

bit 24 — signal “Ready to discharge”;

bit 25 — signal “Power up”;

bits 26-31 — not used.

U32
0x200B1

Discrete output signals (bitfield):

bit 0 — state of the output 1;

bit 1 — state of the output 2;

bit 2 — state of the output 3;

bit 3 — state of the output 4;

bits 4-15 — not used.

U16
0x200C1

Power switch states (bitfield):

bit 0 — state of the power switch 1 (0 – open, 1 – closed);

bit 1 — state of the power switch 2 (0 – open, 1 – closed);

bit 2 — state of the power switch 3 (0 – open, 1 – closed);

bit 3 — state of the power switch 4 (0 – open, 1 – closed);

bit 4 — state of the power switch 5 (0 – open, 1 – closed);

bit 5 — state of the power switch 6 (0 – open, 1 – closed);

bits 6-15 — not used.

U16
0x200E2

Errors 2 (bitfield):

bit 0 — error "Low temperature (CH)";

bit 1 — error “High temperature (CH)”;

bit 2 — reserved (set to 0);

bit 3 — reserved (set to 0);

bit 4 — error “Unallowable charging”;

bit 5 — error “Stuck contactor”;

bit 6 — “CH contactor feedback error”;

bit 7 — “DCH contactor feedback error”;

bit 8 — “Insulation fault”;

bit 9 — “PCH contactor feedback error”;

bit 10 — “CH/DCH contactor feedback error”;

bit 11 — “Main contactor feedback error”;

bit 12 — reserved (set to 0);

bit 13 — “General error”;

bit 14 — “High voltage fault”;

bit 15 — “Power switch error”;

bit 16 — “HVIL error”;

bit 17 — “Precharge error”;

bit 18 — “Power fault”;

bits 19-31 — not used.

U32
0x20101Address of the BMS Logic device the parameters of which are in registers 0x2011-0x20C9U16
0x20111

BMS Logic state (bitfield):

bit 0 — device is present;

bit 1 — device is online;

bit 2 — device is ready;

bit 3 — data from the device is actual;

bit 4 — temperature sensor 1 is present;

bit 5 — temperature sensor 2 is present;

bit 6 — temperature sensor 1 is shorted;

bit 7 — temperature sensor 2 is shorted;

bits 8-15 — not used.

U16
0x2012-0x20132BMS Logic device temperature, °CREAL32
0x2014-0x20152

Cell balancing flags (bitfield):

bit i — balancing resistor is connected to the (i+1)th cell.

U32
0x2016-0x202920

Array of cell states. Each element of the array corresponds to a cell and is a bitfield:

bit 0 — cell is present;

bit 1 — temperature sensor is present;

bit 2 — need to connect a balancing resistor to the cell;

bit 3 — balancing resistor is connected to the cell;

bit 4 — temperature sensor is shorted;

bit 5 — wires are connected to the cell;

bits 6-15 — not used.

U16[20]
0x202A-0x205140Array of cell voltages (V)REAL32[20]
0x2052-0x207940Array of cell temperatures (°C)REAL32[20]
0x207A-0x20A140Array of cell SOCs (%)REAL32[20]
0x20A2-0x20C940Array of cell resistances (Ohm)REAL32[20]
0x20CA1

BMS Logic board version:

byte 0 – minor;

byte 1 – major.

U8[2]
0x20CB-0x20CC2

BMS Logic firmware version:

byte 0 – patch;

byte 1 – minor;

byte 2 – major;

byte 3 – not used (set to 0).

U8[4]
0x20CD1Number of cells BMS Logic can manageU16
0x20CE1BMS Logic serial numberU16
0x20F0-0x20F12Temperature (sensor 2), °CREAL32
0x20F2-0x20F32Device supply voltage, VREAL32
0x20F41

Discrete input signals 2 (bitfield):

bit 0 — signal "Fuse 2";

bit 1 — signal "Fuse 3";

bit 2 — signal "Circuit breaker status";

bit 3 — signal "Balancing request";

bit 4 — signal "Close Main contactor";

bits 5-15 — not used.

U16
0x2100-0x21012Battery state of charge (SOC), %REAL32
0x21021Number of connected BMS Logic devicesU16
0x21031Number of connected cellsU16
0x2104-0x21052Battery voltage, VREAL32
0x2106-0x21072Battery resistance, OhmREAL32
0x2108-0x21092Effective capacity, A×hREAL32
0x210A-0x210B2Balancing effectivity, %REAL32
0x210C-0x210D2State of health, %REAL32
0x210E-0x210F2Depth of discharge, A×hREAL32
0x2110-0x21112Minimum BMS Logic temperatureREAL32
0x21121Address of the BMS Logic device whose temperature is minimalU16
0x2113-0x21142Maximum BMS Logic temperatureREAL32
0x21151Address of the BMS Logic device whose temperature is maximalU16
0x2116-0x21172BMS Logic polling rate, commands pre secondREAL32
0x2118-0x21192Minimum cell temperatureREAL32
0x211A1Address of the BMS Logic device which is connected to the cell whose temperature is minimalU16
0x211B1Position of the cell whose temperature is minimalU16
0x211C-0x211D2Maximum cell temperatureREAL32
0x211E1Address of the BMS Logic device which is connected to the cell whose temperature is maximalU16
0x211F1Position of the cell whose temperature is maximalU16
0x2120-0x21212Minimum cell voltageREAL32
0x21221Address of the BMS Logic device which is connected to the cell whose voltage is minimalU16
0x21231Position of the cell whose voltage is minimalU16
0x2124-0x21252Maximum cell voltageREAL32
0x21261Address of the BMS Logic device which is connected to the cell whose voltage is maximalU16
0x21271Position of the cell whose voltage is maximalU16
0x21281

Error flag:

0 — no errors;

1 — there are some errors.

U16
0x2130-0x21312Energy received from the charger, W×hREAL32
0x2132-0x21332Energy consumed by the load, W×hREAL32
0x2134-0x21352Energy dissipated by the balancing resistors, W×hREAL32
0x217B-0x217C2Coulomb received from the charger, A×hREAL32
0x217D-0x217E2Coulomb consumed by the load, A×hREAL32
0x21B81Flag indicating that some cell is being balancedU16
0x21CA-0x21CB2Average cell voltage, VREAL32
0x24002Current (sensor 1, low range), AREAL32
0x24022Final battery current, AREAL32
0x24101

Battery state (enumeration):

0 – Unknown;

1 – Charging ON;

2 – Charging OFF;

3 – Relaxed (after charging);

4 – Discharging ON;

5 – Discharging OFF;

6 – Relaxed (after discharging).

U16
0x24112Duration of the battery state (0x2410), secondsU32

Holding registers

Register addressNumber of registersContentType
0x40001Address of the BMS Logic device whose parameters should be in the input registers 0x2011-0x20C9U16
0x51001

Software control of the "Battery cover" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Battery cover".

U16
0x51011

Software control of the "Charger connected" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Charger connected".

U16
0x51021

Software control of the "Power up/down request" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Power down request".

U16
0x51031

Software control of the "Inhibit charging" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Inhibit charging".

U16
0x51041

Software control of the "Inhibit discharging" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Inhibit discharging".

U16
0x51051

Software control of the "CH contactor feedback" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Charging contactor feedback".

U16
0x51061

Software control of the "DCH contactor feedback" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Discharging contactor feedback".

U16
0x51071

Software control of the "Insulation status" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Insulation status".

U16
0x51081

Software control of the "Charge request" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Charge request".

U16
0x51091

Software control of the "Precharge request" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Precharge request".

U16
0x510A1

Software control of the "Discharge request" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Discharge request".

U16
0x510B1

Software control of the "PCH contactor feedback" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "PCH contactor feedback".

U16
0x510C1

Software control of the "CH/DCH contactor feedback" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "CH/DCH contactor feedback".

U16
0x510D1

Software control of the "Main contactor feedback" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Main contactor feedback".

U16
0x510E1

Software control of the "Interlock" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Interlock".

U16
0x510F1

Software control of the "Fuse 1" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Fuse 1".

U16
0x51101

Software control of the "Fuse 2" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Fuse 2".

U16
0x51111

Software control of the "Fuse 3" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Fuse 3".

U16
0x51121

Software control of the "Circuit breaker status" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Circuit breaker status".

 
0x51131

Software control of the "Balancing request" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Balancing request".

 
0x51141

Software control of the "Close Main contactor" signal. Allowable values:

0 – clear the signal;

1 – set the signal;

2-65535 – use the physical input "Close Main contactor".