---
title: "Sinclair Ontario Heat Pump"
description: "Sinclair S-Therm Ontario monoblock air-to-water heat pump with Modbus RTU control via RS-485."
url: "https://taphome.com/en/compatibility/sinclair-ontario/"
language: en
lastmod: 2026-10-08
generator: hugo
ai:
  topics: ["modbus-rtu","heat-pump","rs485","air-to-water","hot-water","weather-dependent","floor-heating"]
  questions: ["How to integrate Sinclair Ontario heat pump with TapHome?","What does the Sinclair Ontario TapHome template control?","How to connect Sinclair Ontario via RS-485 to TapHome?","How to set the Modbus address on the Sinclair Ontario wired controller?","How to configure weather-dependent heating with Sinclair Ontario via TapHome?","How to monitor error codes from Sinclair Ontario heat pump in TapHome?"]
---

# Sinclair Ontario Heat Pump

Communication: Modbus RTU

- [Sinclair S-Therm Ontario Product Page](https://www.sinclair-solutions.com/en/products/heat-pumps/s-therm-ontario)
- [Sinclair Official Website](https://www.sinclair-solutions.com)

The Sinclair S-Therm Ontario (SMH-xxxIRB series) is a DC inverter air-to-water monoblock heat pump that connects to TapHome via Modbus RTU over RS-485. The template provides comprehensive control of heating, cooling, hot water production, floor commissioning, disinfection, and weather-dependent operation. The heat pump uses R32 refrigerant and is available in 1-phase (4–16 kW) and 3-phase (10–16 kW) variants.

The template exposes 38 devices covering temperature sensors, setpoint controls, operation modes, timer functions, and outdoor unit diagnostics with monitoring of 38 error and protection coils.

## Hardware connection

### Indoor unit PCB overview

![Sinclair Ontario indoor unit PCB layout showing RS-485 connectors CN1-CN4](https://taphome.com/images/compatibility/sinclair-ontario/pcb-indoor-unit-p039_hu_cea1fc5d396b207f.jpg)

The indoor unit PCB has **4 RS-485 connectors** for Modbus communication:

| Connector | Type | Pinout |
|-----------|------|--------|
| **CN1** | RS-485 with 12V (4-pin) | 1: +12V, 2: B, 3: A, 4: GND |
| **CN2** | RS-485 without 12V (4-pin) | 1: B, 2: A |
| **CN3** | RS-485 without 12V (3-pin) | B, A |
| **CN4** | RS-485 with 12V (4-pin) | 1: GND, 2: B, 3: A, 4: +12V |

**For TapHome:** Use connector **CN3** (3-pin, RS-485 without 12V) or **CN2** (4-pin, RS-485 without 12V) for the BMS connection to TapHome Core:

- **B** → B-/D- on TapHome RS-485
- **A** → A+/D+ on TapHome RS-485

### Wired controller RS-485 interface

The wired controller provides two communication interfaces:

| Interface | Type | Pinout | Use |
|-----------|------|--------|-----|
| **1 — BMS** | 2-wire, AWG24 twisted pair | 1: B, 2: A | Connect to BMS/TapHome via RS-232 to RS-485 converter |
| **2 — +12VDC** | 4-wire, AWG24, 8m max | 1: +12VDC, 2: B, 3: A, 4: GND | Equipment communication line (powered by equipment) |

> [!WARNING]
> **Important — Interface 1 outputs RS-485 signals.** If connecting through the wired controller BMS port, an RS-232 to RS-485 converter is required. For direct RS-485 connection, use the indoor unit PCB connectors (CN1–CN4) instead.

### Technical specifications

- **Communication:** Modbus RTU, RS-485
- **Baud rate:** 9600, no parity, 1 stop bit
- **Slave ID range:** 1–253 (default 1)
- **Cable:** AWG24 twisted pair, Class V
- **Protocol:** Read Multiple Coils (0x01), Read Multiple Registers (0x03), Write Multiple Coils (0x0F), Write Multiple Registers (0x10)

## Configuration

### Setting the Modbus address

The Modbus Slave ID is configured via the wired controller touchscreen:

1. Power on the controller, press **COMMISSION** to access the COMMISSION page
2. Press **FUNCTION** to go to the FUNCTION page
3. Press **Next** (rightmost button) to navigate to FUNCTION page 4/4 where "Address" is displayed
4. Select **Address** and use **+** / **-** to set the desired value (range 1–253, default 1)
5. Press **OK** to save

![Sinclair Ontario wired controller COMMISSION menu for Modbus address setup](https://taphome.com/images/compatibility/sinclair-ontario/bms-address-commission-screen_hu_edcd667ced7f4590.jpg)

![Sinclair Ontario address setting screen showing range 1-253](https://taphome.com/images/compatibility/sinclair-ontario/bms-address-setting-screen_hu_62a57d0934c90146.jpg)

> [!WARNING]
> **Address 0 and 126 cannot be used.** Address 0 is reserved for broadcast (received by all units), and address 126 is reserved.

### Communication precautions

- Operation modes can only be changed when the unit is **OFF**
- For heating-only units, "Cool" and "Cool+Hot water" settings are ineffective
- When the water tank is unavailable, "Hot water", "Cool+Hot water", and "Heat+Hot water" modes are ineffective
- Parameter modifications with memory function activated work immediately but are memorized after **30 minutes**

## Device capabilities

### Power and operation mode

- **ON/OFF** (H:42) — turns the heat pump on or off. Uses special encoding: 0xAA (170) = ON, 0x55 (85) = OFF. The ON/OFF state is shared across multiple devices (Holiday Mode, Manual Defrost, and Floor Debug check it before allowing changes)
- **Operation Mode** (H:2) — selects Heat, Hot water, Cool+Hot water, Heat+Hot water, or Cool. Modes can only be changed when the unit is OFF. The template warns if a water-related mode is selected but no water tank is available

### Temperature setpoints

The template provides separate setpoints for each control scenario:

- **Water Outlet Temperature Heating Setpoint** (H:10) — target water outlet temperature for heating, 20–60°C (high-temp) or 20–55°C (low-temp), default 45°C
- **Water Outlet Temperature Cooling Setpoint** (H:9) — target water outlet temperature for cooling, 7–25°C, default 18°C
- **Room Temperature Heating Setpoint** (H:12) — room temperature target for heating, 18–30°C, default 20°C (active only when Control State is set to T-room)
- **Room Temperature Cooling Setpoint** (H:11) — room temperature target for cooling, 18–30°C, default 24°C (active only when Control State is set to T-room)
- **Control State** (C:17) — switches between water outlet temperature control (T-water out) and room temperature control (T-room). Has a service attribute showing whether a remote room sensor is installed (C:33), and a service action to configure it

### Temperature monitoring

The template reads 9 temperature sensors from the heat pump, all using ÷10 conversion from raw register values:

- **Outdoor Temperature** (H:118) — ambient outdoor air temperature
- **Water Outlet Temperature** (H:125) — water leaving the plate heat exchanger
- **Water Inlet Temperature** (H:127) — water entering the plate heat exchanger
- **Gas Pipe Temperature** (H:130) — refrigerant vapor line temperature
- **Liquid Pipe Temperature** (H:131) — refrigerant liquid pipe temperature
- **Discharge Pressure** (H:124) — compressor discharge pressure as saturated temperature equivalent
- **Optional Water Sensor Temperature** (H:126) — optional water temperature sensor reading
- **Remote Room Temperature** (H:129) — remote room sensor reading (warns if remote sensor is not available)
- **Hot Water Tank** (H:128) — current water tank temperature with setpoint control (H:13, range 40–80°C)

### Hot water tank

**Hot Water Tank** reads the current tank temperature (H:128, ÷10) and controls the desired temperature (H:13, range 40–80°C, default 50°C). The ReadScript monitors whether a water tank is installed (C:29) and checks for sensor errors (C:156).

Six service attributes provide additional monitoring:
- Water Tank Heater State, Tank Heater Logic, Other Thermal Logic
- Delta-T hot water (2–8°C), Cool+Hot Water Priority, Heat+Hot Water Priority

Four service actions allow configuration of tank heater logic, hot water differential, and mode priorities.

### Temperature differentials

Three thermostat devices control hysteresis bands:

- **Delta-T Cooling** (H:29) — cooling temperature differential, 2–10°C, default 5°C
- **Delta-T Heating** (H:30) — heating temperature differential, 2–10°C, default 10°C
- **Delta-T Room Temperature** (H:32) — room temperature differential, 1–5°C, default 2°C

### Weather-dependent operation

**Weather-Dependent Operation** (C:22) enables automatic adjustment of setpoints based on outdoor temperature. When enabled, heating and cooling setpoints are recalculated according to weather curves.

Six service attributes display the current curve parameters:
- **AT-Heat / AT-Cool** — ambient temperature lower/upper bounds
- **RT-Heat / RT-Cool** — room temperature lower/upper bounds
- **WT-Heat / WT-Cool** — water temperature lower/upper bounds

### Timers and scheduling

- **Weekly Timer** (C:8) — enables/disables weekly timer schedule
- **Clock Timer** (C:9) — enables/disables clock timer function
- **Temperature Timer** (C:10) — enables/disables temperature-based timer function

### Comfort and energy features

- **Quiet Mode** (C:21) — reduces running noise via automatic compressor and fan speed control. Available in cooling, heating, and water heating modes
- **Fast Hot Water** (C:18) — runs heat pump + water tank e-heater simultaneously for faster hot water production
- **Solar Heater** (C:16) — enables solar heater priority for energy conservation. Warns if solar is not available. Has a service attribute and action for configuring solar availability (C:31)
- **Holiday Mode** (C:34) — keeps indoor/water temperature in range to prevent freezing. Only for heating. Requires system OFF to enable
- **Emergency Mode** (C:26) — enables emergency heating via e-heater only when outdoor unit fails

### E-heater and auxiliary configuration

- **Optional E-Heater** (H:3) — configures auxiliary electric heater count: 1 set, 2 sets, or Off
- **E-Heater Activation Temperature** (H:14) — outdoor temperature threshold for e-heater activation, -20 to 18°C, default -15°C

### Thermostat

- **Thermostat Configuration** (H:39) — configures external thermostat connection type: Without, Air, or Air+Hot water
- **Thermostat State** (H:132) — reads external thermostat demand: Cool, Heat, or Off

### Floor commissioning

**Floor Commissioning** (C:25) manages the floor preheating process for initial floor heating system use. The system must be turned OFF before enabling.

Four service attributes monitor the commissioning process:
- Floor Debug Segments (1–10 sections), Period 1 Temperature (25–35°C)
- Delta-T of Segment (2–10°C), Segment Time (12–72 hours)

Six service actions control the process: Enable, Start, Stop, and individual parameter configuration.

### Disinfection

**Disinfection** (H:135 read / C:23 write) manages the water system disinfection cycle with status reporting: Off, Running, Done, or Failed. A service attribute shows the disinfection temperature setpoint (H:4, range 40–70°C, default 70°C), and three service actions allow setting the temperature, starting, and stopping the cycle.

### Maintenance functions

- **Manual Defrost** (C:36) — triggers a manual defrost cycle. Requires system OFF to enable
- **Force Mode** (H:40) — for refrigerant recovery and debugging only: Force-cool, Force-heat, or Off
- **Air Removal** (H:41) — purges air from the water system: Air, Water tank, or Off

### Outdoor unit diagnostics

**Outdoor Unit Status** (H:117) reports the current unit state: Cool, Heat, Hot water, or Off. The ReadScript monitors **38 error and protection coils** across three groups:

**Outdoor unit errors** (C:88–C:109): Ambient/defrost/discharge/suction sensor errors, fan error, high/low pressure protection, capacity DIP setting error, economizer sensor errors, system recoverable/irrecoverable protection, flow switch protection, 4-way valve error

**Drive/compressor errors** (C:128–C:151): DC bus voltage errors, AC current protection, IPM/PFC errors, startup error, phase loss, compressor overcurrent, over-speed, desynchronizing, stalling, drive communication error, radiator/IPM overtemperature, charging circuit error, AC input voltage error

**Indoor unit sensor errors**: Condenser/e-heater/refrigerant liquid/vapor/water tank sensor errors, remote room sensor error

Twelve service attributes provide component-level monitoring:
- Compressor State, Fan State, 4-way Valve State
- Crankcase Heater, Underpan Heater, Defrosting State, Oil Return State
- T-discharge, T-defrost, T-suction, T-economizer in/out (all ÷10 °C)

### Module-level service attributes and actions

The module exposes 11 service attributes for system configuration monitoring:
- **T-HP max** — maximum heat pump outlet temperature (40–55°C)
- **Cool/Heat run time** — minimum compressor run time per mode
- **Water Pump State** — indoor unit water pump On/Off
- **Other thermal** — whether other thermal source is enabled, with logic mode and switch-on temperature
- **Other Heat Source State** — On/Off status
- **Optional E-Heater logic** — e-heater logic mode
- **Current limit value** — maximum current limit (0–50 A)
- **Power limit** — power limit in kW (register value x 10)

Ten service actions allow configuration of these parameters, plus an **Error Reset** action (H:44) to clear faults.

### Additional capabilities

The heat pump also exposes registers for gate-card control (C:11), refrigerant recovery (C:35), manual 2-way valve control (C:37), floor debug temperature and remaining time readback (H:133–H:136), weather-dependent calculated setpoint (H:137), and compressor setting/running frequency (H:142–H:143). Communication error coils between the wired controller and indoor/outdoor units and drive (C:64–C:66) are also available. These can be added in a future template update.

## Troubleshooting

### No Modbus communication

1. **Check RS-485 cables:**
   - B wire correctly connected to B-/D- on TapHome
   - A wire correctly connected to A+/D+ on TapHome
   - If using wired controller Interface 1, ensure an RS-232 to RS-485 converter is installed
2. Verify the Modbus Slave address on the wired controller (COMMISSION → FUNCTION 4/4 → Address)
3. Confirm TapHome is set to: **9600 baud, no parity, 1 stop bit**
4. Try using the indoor unit PCB connectors (CN1–CN4) directly instead of the wired controller BMS port

### Mode changes not working

1. Verify the unit is **OFF** before changing the operation mode — mode changes are blocked while the unit is running
2. Check that the water tank is installed (C:29) if selecting Hot water, Cool+Hot water, or Heat+Hot water modes
3. For heating-only units, Cool and Cool+Hot water modes are ineffective

### Holiday Mode / Manual Defrost not activating

1. The unit must be **OFF** (H:42 = 0x55) before these functions can be enabled
2. The template WriteScript checks the ON/OFF state and shows a warning if the system is on

### Sensor errors appearing in TapHome

1. Check the specific error coil in the Outdoor Unit Status service attributes
2. For indoor unit sensor errors (C:152–C:160), inspect the corresponding temperature sensor connections on the PCB
3. Use the **Error Reset** service action (H:44) to clear recoverable faults after resolving the issue

## Available devices

Sinclair Ontario Module

Service Attributes

|                          |                                                                                                          |
|--------------------------|----------------------------------------------------------------------------------------------------------|
| T-HP max \[°C]           | reads H:16 (UInt16); maximum heat pump outlet temperature, range 40–55°C, default 50°C                   |
| Cool run time \[min]     | reads H:33 (UInt16); minimum compressor run time in cooling mode, range 1–10 min, default 3 min          |
| Heat run time \[min]     | reads H:34 (UInt16); minimum compressor run time in heating mode, range 1–10 min, default 5 min          |
| Water Pump State         | reads C:175 (Bool); On/Off status of indoor unit water pump                                              |
| Other thermal            | reads C:27 (Bool); With/Without — whether other thermal source is enabled                                |
| Other thermal logic      | reads H:35 (UInt16); other thermal source logic mode 1–3                                                 |
| T-Other switch on \[°C]  | reads H:15 (Int16); outdoor temperature threshold for other thermal source activation, range -20 to 18°C |
| Other Heat Source State  | reads C:169 (Bool); On/Off status of other heat source                                                   |
| Optional E-Heater logic  | reads H:37 (UInt16); optional e-heater logic mode 1–2                                                    |
| Current limit value \[A] | reads H:38 (UInt16); maximum current limit, range 0–50 A, default 16 A                                   |
| Power limit \[kW]        | reads H:43 (UInt16) × 10; power limit in kW (register value × 10), range 0–10 kW                         |

Service Actions

|                                |                                                                        |
|--------------------------------|------------------------------------------------------------------------|
| Set T-HP max                   | writes H:16 (UInt16); range 40–55°C                                    |
| Set Cool run time              | writes H:33 (UInt16); range 1–10 min                                   |
| Set Heat run time              | writes H:34 (UInt16); range 1–10 min                                   |
| Set Other thermal              | writes C:27 (Bool); 0=Without, 1=With                                  |
| Set Other thermal logic        | writes H:35 (UInt16); range 1–3                                        |
| Set T-Other switch on          | writes H:15 (Int16); range -20 to 18°C                                 |
| Change Optional E-Heater logic | writes H:37 (UInt16); range 1–2                                        |
| Change Current limit value     | writes H:38 (UInt16); range 1–50 A                                     |
| Change Power limit             | writes H:43 (UInt16); value in 0.1 kW units, range 1–100 (= 0.1–10 kW) |
| Reset error                    | writes H:44 (UInt16); 0=Does not clear fault, 1=Clear fault            |

Delta-T Cooling Thermostat

Cooling temperature differential — controls hysteresis band around cooling setpoint (2–10°C)

Register: H:29 UInt16 Unit: °C numeric

Delta-T Heating Thermostat

Heating temperature differential — controls hysteresis band around heating setpoint (2–10°C)

Register: H:30 UInt16 Unit: °C numeric

Delta-T Room Temperature Thermostat

Room temperature differential for thermostat on/off cycling (1–5°C)

Register: H:32 UInt16 Unit: °C numeric

Air Removal Multi-value Switch

Water system air purge — Air, Water tank, or Off

Register: H:41 UInt16 numeric

Values / States: Air · Water tank · Off

Clock Timer Switch

Register: C:9 Bool

Values / States: ON · OFF

Control State Switch

Selects control mode — T-water out (water outlet temperature) or T-room (room temperature)

Register: C:17 Bool

Values / States: T-room · T-water out

Service Actions

|                   |
|-------------------|
| Set Remote sensor |

Discharge Pressure Temperature Sensor Read-only

Compressor discharge pressure as saturated temperature equivalent

Register: H:124 Int16 Unit: °C numeric

Disinfection Multi-value Switch

Water system disinfection cycle status — Off, Running, Done, or Failed

Register: H:135 → C:23 UInt16 numeric

Values / States: Off · Running · Done · Failed

Service Actions

|                       |
|-----------------------|
| Set Disinfection Temp |
| Start Disinfection    |
| Stop Disinfection     |

Emergency Mode Switch

Emergency heating via e-heater only — activates when outdoor unit fails

Register: C:26 Bool

Values / States: ON · OFF

Fast Hot Water Switch

Simultaneous heat pump + e-heater operation for faster water heating

Register: C:18 Bool

Values / States: ON · OFF

Floor Commissioning Reed Contact Read-only

Floor preheating process for initial floor heating system use — requires system OFF

Register: C:25 Bool

Service Attributes

|                           |
|---------------------------|
| Floor Debug Segments      |
| Floor Debug Period 1 temp |
| Delta-T of segment        |
| Segment time              |

Service Actions

|                               |
|-------------------------------|
| Enable Floor Debug            |
| Start Floor Debug             |
| Stop Floor Debug              |
| Set Floor Debug Segments      |
| Set Floor Debug Period 1 temp |
| Set Delta-T of segment        |
| Set Segment time              |

Force Mode Multi-value Switch

Forced operation for refrigerant recovery and debugging only — not for normal use

Register: H:40 UInt16 numeric

Values / States: Force-cool · Force-heat · Off

Holiday Mode Switch

Keeps indoor/water temperature in range to prevent freezing — heating only, requires system OFF

Register: C:34 Bool

Values / States: ON · OFF

Hot Water Tank Thermostat

Water tank temperature and setpoint control (40–80°C) with heater state and priority monitoring

Register: H:128 → H:13 Int16 Unit: °C numeric

Service Attributes

|                         |
|-------------------------|
| Water Tank Heater State |
| Tank heater Logic       |
| Other thermal logic     |
| Delta-T hot water       |
| Cool+Hot Water Priority |
| Heat+Hot Water Priority |

Service Actions

|                             |
|-----------------------------|
| Set Tank heater Logic       |
| Set Delta-T hot water       |
| Set Cool+Hot Water Priority |
| Set Heat+Hot Water Priority |

Manual Defrost Switch

Triggers manual defrost cycle — requires system OFF

Register: C:36 Bool

Values / States: ON · OFF

Operation Mode Multi-value Switch

Heat pump operating mode — Heat, Hot water, Cool+Hot water, Heat+Hot water, or Cool

Register: H:2 UInt16 numeric

Values / States: Heat · Hot water · Cool+Heat water · Heat +Hot water · Cool

ON/OFF Switch

Register: H:42 UInt16 numeric

Values / States: ON · OFF

Optional E-Heater Multi-value Switch

Auxiliary electric heater configuration — 1 set, 2 sets, or Off

Register: H:3 UInt16 numeric

Values / States: 1 set · 2 sets · Off

Outdoor Unit Status Multi-value Switch Read-only

Outdoor unit operating state with 38 error/protection coil monitoring and component diagnostics

Register: H:117 UInt16 numeric

Values / States: Cool · Heat · Hot water · Off

Quiet Mode Switch

Reduces running noise via automatic compressor and fan speed control

Register: C:21 Bool

Values / States: ON · OFF

Room Temperature Cooling Setpoint Thermostat

Room temperature target for cooling — active only when Control State is set to T-room (18–30°C)

Register: H:11 UInt16 Unit: °C numeric

Room Temperature Heating Setpoint Thermostat

Room temperature target for heating — active only when Control State is set to T-room (18–30°C)

Register: H:12 UInt16 Unit: °C numeric

Solar Heater Switch

Solar heater priority for energy conservation — warns if solar is not available

Register: C:16 Bool

Values / States: ON · OFF

Service Actions

|           |
|-----------|
| Set Solar |

E-Heater Activation Temperature Thermostat

Outdoor temperature threshold for auxiliary electric heater activation (-20 to 18°C)

Register: H:14 Int16 Unit: °C numeric

Gas Pipe Temperature Temperature Sensor Read-only

Refrigerant gas pipe (vapor line) temperature

Register: H:130 Int16 Unit: °C numeric

Liquid Pipe Temperature Temperature Sensor Read-only

Refrigerant liquid pipe temperature

Register: H:131 Int16 Unit: °C numeric

Optional Water Sensor Temperature Temperature Sensor Read-only

Register: H:126 Int16 Unit: °C numeric

Outdoor Temperature Temperature Sensor Read-only

Register: H:118 Int16 Unit: °C numeric

Remote Room Temperature Temperature Sensor Read-only

Remote room temperature sensor reading — warns if remote sensor is not available

Register: H:129 Int16 Unit: °C numeric

Water Inlet Temperature (Plate Exchanger) Temperature Sensor Read-only

Register: H:127 Int16 Unit: °C numeric

Water Outlet Temperature (Plate Exchanger) Temperature Sensor Read-only

Register: H:125 UInt16 Unit: °C numeric

Temperature Timer Switch

Register: C:10 Bool

Values / States: ON · OFF

Thermostat Configuration Multi-value Switch

External thermostat connection type — Without, Air, or Air+Hot water

Register: H:39 UInt16 numeric

Values / States: Without · Air · Air + Hot water

Thermostat State Multi-value Switch Read-only

External thermostat demand status — Cool, Heat, or Off

Register: H:132 Int16 numeric

Values / States: Cool · Heat · Off

Weather-Dependent Operation Switch

Automatic setpoint adjustment based on outdoor temperature using weather curves

Register: C:22 Bool

Values / States: ON · OFF

Weekly Timer Switch

Register: C:8 Bool

Values / States: ON · OFF

Water Outlet Temperature Cooling Setpoint Thermostat

Water outlet temperature target for cooling — active when Control State is T-water out (7–25°C)

Register: H:125 → H:9 UInt16 Unit: °C numeric

Water Outlet Temperature Heating Setpoint Thermostat

Water outlet temperature target for heating — active when Control State is T-water out (20–60°C)

Register: H:125 → H:10 UInt16 Unit: °C numeric

**Connection:** Modbus RTU • 9600 baud• 8N1 • Slave ID: $\[SlaveId]

Possible improvements (16)

- C:11 Gate-Ctrl. — Gate card control — 0=Close, 1=Open. Hotel gate-card integration.
- C:35 Refrigerant Recovery — 0=Off, 1=On. For service/maintenance — refrigerant recovery mode.
- C:37 Cool 2-Way Valve — 0=Off, 1=On. Manual control of cooling 2-way valve.
- H:117 Unit Status (as sensor) — Currently exposed as Outdoor Unit multi-value switch; could be a dedicated read-only sensor. Values: 01=Cool, 02=Heat, 06=Hot water, 08=Off.
- H:133 T-floor debug — Current calculated floor debug temperature. Available as read-only sensor.
- H:134 Debug time — Remaining floor debug time in hours.
- H:136 Error Time for Floor Debug — Floor debug error timeout in seconds.
- H:137 T-weather depend — Current calculated weather-dependent setpoint temperature.
- H:142 Setting frequency — Compressor target frequency, 0–100 Hz.
- H:143 Running frequency — Compressor actual running frequency, 0–100 Hz.
- C:38 Heat 2-Way Valve — Read-only. 0=Off, 1=On. Heating 2-way valve state.
- C:64 Comm Error IDU-Wired Controller — Read-only. 1=Error. Communication error between wired controller and indoor unit.
- C:65 Comm Error ODU-Wired Controller — Read-only. 1=Error. Communication error between wired controller and outdoor unit.
- C:66 Comm Error Drive-Wired Controller — Read-only. 1=Error. Communication error between wired controller and drive.
- C:67 HP-Antifree — Read-only. 0=Off, 1=On. Heat pump antifreeze protection active.
- C:152-191 Indoor Unit Sensor/State Coils — Various indoor unit sensor errors and component states (E-heater, water pump, valves, etc.). Partially covered by Hot Water Tank readscript (C:156) and Outdoor Unit readscript. Remaining: C:152 (condenser leaving water), C:153 (e-heater leaving water), C:154 (refrigerant liquid), C:155 (condenser entering water), C:158 (vapor line), C:160 (remote room — covered by Control State), C:169–C:191 (component states — partially covered by module service attributes).

## Sources

- Sinclair S-Therm Modbus Protocol V15.2
  
  2026-03-20
  
  [PDF](https://taphome.com/compatibility/devices/sinclair-ontario/manufacturer/modbus-protocol-v15.pdf)
- Sinclair S-Therm Ontario Monoblock Installation Manual
  
  [www.sinclair-solutions.com](https://www.sinclair-solutions.com/files/instalation-manual-en/sinclair-im-smh-xxxirb-irb-3-irb2-irb2-3-en.pdf) 2026-03-20
  
  [PDF](https://taphome.com/compatibility/devices/sinclair-ontario/manufacturer/installation-manual-monoblock.pdf)

## Related Documentation

- [Modbus Integration](https://taphome.com/en/compatibility/modbus-guide/)
- [Modbus](https://taphome.com/en/docs/integration/modbus/)
- [Simple configuration using templates](https://taphome.com/en/docs/integration/modbus/templates/)
- [Modbus scripts and prefetch](https://taphome.com/en/docs/script/modbus-scripts/)
- [Modbus functions](https://taphome.com/en/docs/script/modbus/)
- [Modbus data types](https://taphome.com/en/docs/script/modbus-data-types/)