Pylontech FORCE H2: Modbus RS485 BMS and KNX Self-Consumption Scenes

Pylontech FORCE H2 Architecture

Pylontech FORCE H2 is a modular 48V LFP battery system: each 3.55 kWh module stacks to 7.1-107.1 kWh. Communication: CAN bus (primary, for SMA/Victron/Solis inverters) and RS485 Modbus RTU (secondary BMS port for monitoring).

The RS485 port (RJ45 on front panel, pins 3/6 = B+/B-, pin 5 = GND) provides battery telemetry read-only. Modbus RTU baud 9600, 8N1, unit ID 2 (default — verify on battery label).

Pylontech RS485 Register Map

Holding registers (FC3, read-only):

For KNX: read register 4099 and divide by 10 to get SOC percentage (DPT 5.001). Read register 4097 (signed int16): power in W = (current value / 10) multiplied by (voltage register 4096 value / 1000), giving V times A = W. Alternatively use inverter Modbus TCP for power W directly, which avoids the multiplication step.

Inverter Indirect Integration (Deye/Sungrow)

Pylontech FORCE H2 + Deye SUN-5K-SG04LP1-EU: Deye hybrid inverter Modbus TCP port 502, unit ID 1. Battery registers in Deye:

Sungrow SH5.0RS + Pylontech: Sungrow Modbus TCP port 502, unit ID 1. Battery SOC at register 13022 (uint16, %), battery power at register 13021 (int16, W, positive=charging). Read with FC3.

MDT Modbus Gateway Setup

For direct RS485 approach: MDT SCN-MOD.02 RS485 port connected to Pylontech RS485 RJ45 (pins 3/6). MODBUS RTU mode, baud 9600, 8N1, unit 2. Read task: registers 4096-4106 (11 registers, 30s interval). Map: reg 4099 / 10 to KNX DPT 5.001 GA 6/4/6 (Pylontech SOC). Status word reg 4106: bit 3 to KNX DPT 1.005 GA 8/0/5 (over-current discharge alarm).

KNX Scene Control with SOC Hysteresis

MDT Logic Controller EibScript logic with two-threshold hysteresis:

// Hysteresis thresholds
VAR soc_high : REAL := 80.0;
VAR soc_low  : REAL := 25.0;
VAR load_enabled : BOOL := FALSE;

ON CHANGE GA("6/4/6") DO
  IF (READ_GA("6/4/6") > soc_high) AND (NOT load_enabled) THEN
    WRITE_GA("1/5/0", 1);    // Enable flex load group
    load_enabled := TRUE;
  ELSIF (READ_GA("6/4/6") < soc_low) AND load_enabled THEN
    WRITE_GA("1/5/0", 0);    // Disable flex load group
    load_enabled := FALSE;
  END_IF;
END_ON;

This two-threshold hysteresis (engage at 80%, disengage at 25%) prevents rapid cycling that would reduce battery cycle life. The MDT Logic Controller retains variable values across KNX bus power cycles (EEPROM storage).

Multi-Stack Scaling

Pylontech FORCE H2 supports up to 15 modules per stack (53.25 kWh), multiple stacks per system. All modules share the same Modbus address — register 4099 reports aggregate SOC for the full stack. No per-module addressing is needed for KNX automation. For multi-stack systems (separate battery cabinets), each cabinet has a separate RS485 port and unit ID. Wire separate RS485 chains to MDT gateway RS485 A and B ports using Modbus multi-drop topology (120 ohm termination resistor on last device in each chain).