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.

Documents

Installation Sheet

Modbus RTU Master.jpg

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

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]


Modus1.png


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]