STIEBEL ELTRON · Heat pump
WPM / WPM 3 / WPM 3i heat pump manager via ISG web Modbus register map
Default configuration
- Protocol
- Modbus TCP
- Port
- 502
- Unit ID
- 1
- Addressing
- 1-based
- Byte order
- Big endian
- Word order
- High word first
Register map
| Address | Count | Name | Type | Unit | Scale | Access |
|---|---|---|---|---|---|---|
| 507 | 1 | Outside temperature | Int16 | °C | 0.1 | R |
| 508 | 1 | Actual temperature heating circuit 1 Room temperature of heating circuit 1 (WPMsystem, WPM 3). | Int16 | °C | 0.1 | R |
| 509 | 1 | Set temperature heating circuit 1 | Int16 | °C | 0.1 | R |
| 511 | 1 | Actual temperature heating circuit 2 | Int16 | °C | 0.1 | R |
| 512 | 1 | Set temperature heating circuit 2 | Int16 | °C | 0.1 | R |
| 513 | 1 | Actual flow temperature heat pump | Int16 | °C | 0.1 | R |
| 514 | 1 | Actual flow temperature additional heat stage | Int16 | °C | 0.1 | R |
| 515 | 1 | Actual flow temperature | Int16 | °C | 0.1 | R |
| 516 | 1 | Actual return temperature | Int16 | °C | 0.1 | R |
| 518 | 1 | Actual buffer temperature | Int16 | °C | 0.1 | R |
| 519 | 1 | Set buffer temperature | Int16 | °C | 0.1 | R |
| 521 | 1 | Flow rate | Int16 | l/min | 0.1 | R |
| 522 | 1 | Actual DHW temperature | Int16 | °C | 0.1 | R |
| 523 | 1 | Set DHW temperature | Int16 | °C | 0.1 | R |
| 2501 | 1 | Operating status Bit-coded: B0 = heating circuit 1 pump, B1 = heating circuit 2 pump, B2 = heat-up program, B3 = additional heat stages running, B4 = heat pump in heating mode, B5 = heat pump in DHW mode, B6 = compressor running, B7 = summer mode active, B8 = cooling mode active, B9 = at least one heat pump in defrost, B10 = silent mode 1 active, B11 = silent mode 2 active (heat pump off). | UInt16 | - | 1 | R |
| 2502 | 1 | Power-off (utility lock) Bit-coded: B0 = power-off active (EVU lock). | UInt16 | - | 1 | R |
| 2503 | 1 | Operating status compressors and buffer pumps Bit-coded: B0-B5 = compressor 1-6, B6-B11 = buffer charging pump 1-6. | UInt16 | - | 1 | R |
| 2504 | 1 | Fault status 0 = no fault, 1 = system fault. Faults can only be acknowledged on the ISG service interface, not over Modbus. | UInt16 | - | 1 | R |
| 2506 | 1 | Defrost active 0 = off, 1 = defrost initiated. | UInt16 | - | 1 | R |
| 2507 | 1 | Active fault number | UInt16 | - | 1 | R |
| 2509 | 1 | Heating circuit pump 1 0 = off, 1 = on. Only available on the WPMsystem. | UInt16 | - | 1 | R |
| 2515 | 1 | Source pump 0 = off, 1 = on. Only available on the WPM 3. | UInt16 | - | 1 | R |
| 3680 | 1 | Inverter power consumption, heat pump 1 Electrical input power of inverter heat pump 1; the WPM 3 without inverter does not provide it. | Int16 | kW | 0.1 | R |
| 5001 | 1 | SG Ready operating state 1 = heating system must not start (frost protection assured), 2 = standard operation, 3 = accelerated mode with raised heating and DHW temperatures, 4 = immediate maximum heating and DHW temperatures. | UInt16 | - | 1 | R |
Notes
Source: STIEBEL ELTRON, "Software documentation - Modbus TCP/IP" for the ISG web / ISG plus (document 321798-44755-9770, multilingual, sections 6 and 7: Modbus system values for heat pumps with WPM and further registers). The ISG is the Modbus TCP server on port 502 with the permanent slave ID 1; system values are read from input registers (function code 04) and system parameters from holding registers (function code 03/06/16). ISG addressing is 1-based, hence one_based above: the guide's register 501 is wire address 500. Values are 16-bit; data type 2 = signed x0.1, 7 = signed x0.01, 6 and 8 = unsigned integer, which the scale factors above reflect. Objects that are not available on the connected appliance return the substitute value 32768 (0x8000), so a reading of -3276.8 °C after scaling means "not available". Availability depends on the appliance family: the WPMsystem, WPM 3 and WPM 3i expose different subsets, and the guide marks each row with the families that support it. The Modbus TCP/IP function is a software extension for the ISG (part number 316303) and cannot be combined with other ISG interfaces except read-only access next to the EMI energy management extension. Faults cannot be acknowledged over Modbus, only in the ISG service interface; the heat pump energy and runtime blocks (3501-3560 and up) are not included because their row alignment is only partly unambiguous in the published table.