ModBus RTU Gateway

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The ModBus RTU Gateway allows two way communication from the Building Management System (BMS) to any of our electronic HIU's, using the ModBus Protocol. This allows the building manager to read any of the parameters being monitored by the HIU electronics, such that plantroom controls can be adjusted to optimise the efficiency of the entire district heating system.

In order to work with the ModBus RTU Master, the suitable ModBus software will be required. For testing purposes we have used 'Simply Modbus master', a demo of which can be downloaded here.


Installation Sheet

Modbus RTU Master.jpg

Installation sheet
Installation sheet for the Modbus RTU-Zero Gateway .

Modbus Registers for HIUs

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]

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: HEProtectionMode [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)