Modbus Registers for HIUs
Version 1
These are the standard registers used for Modbus connection to HIUs.
Holding registers:
1: Pr Flow Temp [C] [x10]
2: Pr Diff Pressure [bar] [x100]
3: State [0-10] (See below)
4: PowerUpCounter [x1]
5: ErrorCounter [x1]
6: PressureModeAuto [0/1]
10: Setpoint DHW [C] [x10]
11: WarmupBoost [l/m] [x10]
12: EcoMode [0/1]
13: DHWAntiLegionella [0/1]
14: DHWEcoHeatTemp [C] [x10]
15: DHWEcoHeatTime [minutes] [x1]
20: DHW Flow Rate [l/m] [x10]
21: DHW Output Temp [C] [x10]
22: Pr Rtn Temp DHW [C] [x10]
23: Valve Position DHW [0-270] [x1]
24: Pr Flow Rate DHW [l/m] [x10]
25: DHW Volume [l]
30: DHReturnLimit [C] [x10]
31: HESupply [C] [x10]
32: PumpTimeout [s]
33: DHReturnLimit Enable [0/1]
34: CentralHeatingControl [0/1]
40: Room Thermostat [0/1]
41: CH Output Temp [C] [x10]
42: Pr Rtn Temp CH [C] [x10]
43: Valve Position CH [0-270] [x1]
44: Pr Flow Rate CH [l/m] [x10]
45: CH System Pressure [bar] [x100]
46: CH Pump [0/1]
50: PrePayShutOff [0/1]
Modbus Setup
| Address | 17 |
| Baud | 9600 |
| Data Bits | 8 |
| Parity | None |
| Stop Bits | 2 |
| Data Type | 16INT |
| Function Codes | 3 (read), 6 (write) |
Description of Register 3 - State 0-10
| No | Status | Description |
|---|---|---|
| 0 | INIT | Standard state |
| 1 | INIT_WAIT | |
| 2 | STANDBY | Heating |
| 3 | WARMUP | Start of hot water request |
| 4 | STEADYSTATE | Controlling of hot water temperature |
| 5 | CLOSING | End of hot water request |
| 6 | HOME_STEPPER | |
| 7 | ERROR | |
| 8 | ERROR_WAIT | System stays in this state for 20 Secs, then returns to INIT |
| 9 | PREPAYSHUTOFF | |
| 10 | PREPAYSHUTOFF_WAIT |
Version 2
Version 2 is for Heating Only Sub-Stations. Details are as per version 1 except for register values as below.
Holding registers:
1: Pr Flow Temp [C] [x10]
2: Pr Diff Pressure [bar] [x100] (if available)
4: PowerUpCounter [x1]
5: ErrorCounter [x1]
6: Alarm Count [x1]
7: Warning Count [x1]
30: Primary Return Limit [C] [x10] tHoLimit
31: Central Heating Setpoint [C] [x10] tSetCH
32: Pump Timeout [s] pumpTimeout
33: Primary Return Limit Enabled [0/1] enableHoLimit
34: Central Heating Enabled [0/1]
35: Primary Flow Rate Limit [l/m] fHCHLimit
36: Primary Return Limit and [C] bandHoLimit default 2
37: Setpoint Approach Temperature [C] tApproachCH default 3
40: Room Thermostat [0/1]
41: CH Output Temp [C] [x10]
42: Pr Rtn Temp CH [C] [x10]
43: Valve Position CH [0-100] [x10]
44: Pr Flow Rate CH [l/m] [x10]
45: CH System Pressure [bar] [x100]
46: CH Pump [0/1]
50: PrePayShutOff [0/1]
