---
title: "Samsung MIM-B19N (EHS)"
description: "Samsung MIM-B19N Modbus RTU gateway for HE, HT and EHS heat pump units with R1/R2 Samsung bus connection."
url: "https://taphome.com/en/compatibility/samsung-mim-b19n-ehs/"
language: en
lastmod: 2026-10-08
generator: hugo
ai:
  topics: ["modbus-rtu","heat-pump","rs485","dip-switch","samsung-nasa","domestic-hot-water","water-temperature"]
  questions: ["How to integrate Samsung MIM-B19N with TapHome?","What does the Samsung MIM-B19N TapHome template control?","How to connect Samsung MIM-B19N via RS-485 to TapHome?","How to configure the DIP and rotary switch address on the Samsung MIM-B19N?","How to control Samsung EHS hot water temperature via TapHome?","What is the difference between HE, HT and EHS unit types in the Samsung MIM-B19N template?"]
---

# Samsung MIM-B19N (EHS)

Communication: Modbus RTU

- [Samsung MIM-B19N Product Page](https://www.samsung.com/global/dvms/products/accessory/mim-b19n/)
- [ZimKev MIM-B19N Modbus Repository](https://github.com/ZimKev/MIM-B19n_Modbus)

The Samsung MIM-B19N is a Modbus RTU gateway that connects Samsung HE, HT and EHS heat pump units to TapHome via RS-485. The gateway translates between the Samsung F1/F2 internal bus protocol and standard Modbus RTU (RS-485 terminals R1/R2), exposing water temperature sensors, hot water control, operation modes and comfort functions as holding registers.

Each MIM-B19N can manage up to 1 outdoor unit (4 including sub-units for modular installations) and 48 indoor units. The gateway address is set using a combination of DIP switches and a rotary switch (range 1--247).

## Hardware connection

### Specifications

- **Power supply:** DC 12 V from CN12 on outdoor unit main board
- **Operating temperature:** -10 °C to +50 °C
- **Protocol:** Modbus RTU Slave, RS-485
- **Baud rate:** 9600, even parity, 1 stop bit, 8 data bits
- **Max units:** 48 indoor units + 1 outdoor unit per gateway
- **Max bus length:** 1000 m (RS-485)

### RS-485 wiring

Connect the MIM-B19N to TapHome using a **2-wire RS-485 connection**:

- **A (R1)** --> A+/D+ on TapHome RS-485
- **B (R2)** --> B-/D- on TapHome RS-485

The MIM-B19N draws power from the outdoor unit via the DC 12 V connector (CN12). The Samsung internal communication uses the F1-F2 bus to reach indoor and outdoor units.

> [!WARNING]
> **Important -- RS-485 polarity**
>
> Match the RS-485 polarity between the MIM-B19N and TapHome. Swapped A/B wires will prevent communication. The RED LED on the module blinks when Modbus communication is active -- if it stays off, check the wiring.

### Wiring topology

```text
Outdoor unit ──── F1/F2 ──── MIM-B19N ──── RS-485 (A/B) ──── TapHome Core
  │                              │
  └── 12V/GND (CN12) ───────────┘
  │
  └── F1/F2 ──── Indoor units (up to 48)
```

## Configuration

### DIP and rotary switch addressing

The MIM-B19N address is calculated as the **sum of DIP switch values plus the rotary switch value**.

| Switch | Type | ON value |
|--------|----------|----------|
| SW4-1 | DIP | 128 |
| SW4-2 | DIP | 64 |
| SW5-1 | DIP | 32 |
| SW5-2 | DIP | 16 |
| SW1 | Rotary | 0--15 (hex) |

**Address examples:**

| SW4 (1,2) | SW5 (1,2) | SW1 (rotary) | Address |
|-----------|-----------|-------------|---------|
| OFF, OFF | OFF, OFF | 1 | **1** |
| OFF, OFF | OFF, OFF | 2 | **2** |
| OFF, OFF | OFF, ON | 3 | **19** |
| OFF, OFF | ON, ON | 5 | **53** |

**Recommended:** Address 1 for a single gateway (all DIP switches OFF, rotary switch set to 1).

Address 0 is invalid. Valid range is 1--247.

### Indoor unit prerequisite

Before the MIM-B19N can control indoor units, the **"Use of central control" (SEG5)** setting on each indoor unit must be set to **"Use (1)"**. Without this setting, the gateway can read status but cannot send control commands.

### Multi-unit addressing

For systems with multiple indoor units, register addresses shift by 50 per unit:

| Indoor unit | Base register | ON/OFF register |
|-------------|---------------|-----------------|
| Unit 0 (first) | 50 | H:52 |
| Unit 1 | 100 | H:102 |
| Unit 2 | 150 | H:152 |

The TapHome template is configured for the first indoor unit (IU=0). For additional units, duplicate the template and adjust the register offsets by adding `50 × unit_index`.

## Device capabilities

### Water temperature monitoring

The template provides two water temperature sensors for the hydronic circuit:

- **Water Inlet Temperature** (H:65) -- water return temperature, read-only, °C x 10 conversion
- **Water Outlet Temperature** (H:66 read / H:68 write) -- water flow temperature with setpoint control. The setpoint ranges depend on the unit type:
  - **HE:** Cool 5--25 °C / Heat 15--50 °C
  - **HT:** Heat 25--80 °C (no cooling)
  - **EHS:** Cool 5--25 °C / Heat 15--55 °C

### Hot water (DHW) control

Domestic hot water is managed through three devices:

- **Hot Water ON/OFF** (H:72) -- enables or disables DHW production
- **Hot Water Mode** (H:73) -- selects the DHW mode: ECO, Standard, Power, Force (EHS only), or Cool
- **Hot Water Temperature** (H:75 read / H:74 write) -- current DHW tank temperature and setpoint. Setpoint ranges:
  - **HE:** 30--75 °C
  - **HT:** 35--75 °C
  - **EHS:** 30--70 °C

### Unit power and operation mode

- **Central Heating ON/OFF** (H:52) -- turns the heat pump unit on or off
- **Operation Mode** (H:53) -- selects Auto, Cool, Dry, Fan, or Heat mode

### Quiet mode and away function

- **Quiet Mode** (H:78) -- enables or disables outdoor unit noise reduction (Silence On/Off)
- **Away Function** -- exposed as a service attribute (read H:79) and service action (write H:79) on the Quiet Mode device. Activates the outing/away mode for energy saving when nobody is home

### Service diagnostics

The module exposes three service attributes for system monitoring:

- **Communication Status** (H:50) -- bitfield showing: Exist, Type OK, Ready, Communication error
- **Unit Type** (H:51) -- identifies the connected unit type (HE, HT, EHS, FCU, ERV, AHU, Chiller)
- **Remote Control Restriction** (H:64) -- shows whether the remote controller is locked

Two service actions are available:

- **Buzzer** (H:3) -- turns the outdoor unit buzzer on or off
- **Remote Control Restriction** (H:64) -- locks or unlocks the wired remote controller (write 0x6363 for restriction, 0x0000 for no restriction)

The module ReadScript monitors the MIM-B19N error register (H:0) for address errors, R1/R2 communication errors and tracking errors, and reports the outdoor unit error code (H:1) in TapHome.

### Additional capabilities

The MIM-B19N register map also exposes registers for indoor set temperature (H:58, range 16--30 °C heating / 18--30 °C cooling), discharge temperature (H:60), cooling and heating discharge setpoints (H:61, H:62), indoor unit error codes (H:63), outdoor temperature (community-discovered, H:5), room temperature (H:59), and defrost status (H:2). These can be added in a future template update.

> [!TIP]
> The indoor set temperature register (H:58) is not included in the current template. To control the room setpoint, it can be added as a custom Modbus device in TapHome using holding register 58 with a range of 16--30 and a x10 multiplier.

## LED and 7-segment indicators

| Indicator | Function |
|-----------|----------|
| Y-GRN LED | Blinks during MIM-B19N to outdoor unit communication |
| RED LED | Blinks during Modbus RS-485 communication with BMS/TapHome |

**7-segment error codes:**

| Display | Condition |
|---------|-----------|
| E6 / 16 | All indoor/outdoor communication stopped for >3 minutes |
| E6 / 15 | Specific indoor unit communication stopped for >3 minutes |
| E6 / 04 | Tracking not completed within 10 minutes after power on |
| E6 / 54 | EEPROM error |
| E6 / 34 | Address error |

## Troubleshooting

### No Modbus communication (RED LED not blinking)

1. **Check RS-485 cables:**
   - A wire correctly connected to A+/D+ on TapHome
   - B wire correctly connected to B-/D- on TapHome
   - Verify polarity is not swapped
2. Verify the gateway address using DIP and rotary switches
3. Confirm TapHome is set to: 9600 baud, **even parity**, 1 stop bit, 8 data bits
4. Check that the RS-485 bus length does not exceed 1000 m

### Unit not tracked (Communication Status bits 0--2 not all = 1)

1. Verify indoor unit is powered on and connected to the Samsung F1/F2 bus
2. Check that **"Use of central control" (SEG5)** is set to "Use (1)" on the indoor unit
3. Wait up to 10 minutes for tracking to complete after power-on
4. If 7-segment shows E6/04, reset the MIM-B19N module

### Control commands not taking effect

1. Confirm Communication Status register (H:50) shows bits 0--2 all set to 1 (Exist + Type OK + Ready)
2. Check that Remote Control Restriction is not active (H:64 = 0x0000)
3. Verify the indoor unit address is within range (0--47)
4. Allow at least 10 ms between consecutive Modbus read/write commands

### Temperature readings showing 0 or incorrect values

1. Ensure the unit has completed tracking (Communication Status = Ready)
2. Verify the correct unit type -- some registers are only available for HE/HT/EHS
3. Check the service attribute "Unit Type" in TapHome to confirm the detected model

## Available devices

Samsung MIM-B19N Module

Service Attributes

|                            |                                                                                                                                    |
|----------------------------|------------------------------------------------------------------------------------------------------------------------------------|
| Communication Status       | reads H:50 (UInt16); bitfield: b0=Exist, b1=Type OK, b2=Ready, b3=Communication error                                              |
| Unit Type                  | reads H:51 (UInt16); decodes lower/upper byte to identify unit type: HE (0x6E), HT (0x78), EHS (0x73–0x75), FCU, ERV, AHU, Chiller |
| Remote Control Restriction | reads H:64 (UInt16); 0x0000=No restriction, other=Restriction active                                                               |

Central Heating ON/OFF Switch

Turns the heat pump unit on or off

Register: H:52 Bool

Values / States: ON · OFF

Hot Water Mode Multi-value Switch

Selects DHW mode — ECO, Standard, Power, Force (EHS only), or Cool

Register: H:73 UInt16 numeric

Values / States: ECO · Standart · Power · Force(EHS) · Cool

Hot Water ON/OFF Switch

Enables or disables domestic hot water production

Register: H:72 Bool

Values / States: ON · OFF

Hot Water Temperature Thermostat

Current DHW tank temperature and setpoint control

Register: H:75 → H:74 Int16 Unit: °C numeric

Operation Mode Multi-value Switch

Selects the heat pump operation mode

Register: H:53 Int16 numeric

Values / States: Auto · Cool · Dry · Fan · Heat

Quiet Mode Switch

Enables outdoor unit noise reduction (Silence On/Off)

Register: H:78 Bool

Values / States: Silence on · Silence Off

Water Inlet Temperature Temperature Sensor Read-only

Water return temperature sensor (read-only)

Register: H:65 Int16 Unit: °C numeric

Water Outlet Temperature Thermostat

Water flow temperature with setpoint control

Register: H:66 → H:68 Int16 Unit: °C numeric

**Connection:** Modbus RTU • 9600 baud• 8E1 • Slave ID: $\[SlaveId]

Possible improvements (8)

- H:2 Defrost Status — 0 or 0xFF=Defrost off, Others=Defrost on. Read via module readscript as MODBUSR but not exposed as device
- H:58 Set Temperature (Indoor) — Indoor/room temperature setpoint, °C × 10. Heating: 16–30°C, Cooling: 18–30°C. Missing from template despite being R/W for HE/HT/EHS
- H:60 Discharge Temperature — Discharge temperature °C × 10 — available for HE/HT/EHS. Read-only
- H:61 Cooling Discharge Set Temperature — Cooling discharge setpoint 8–18°C (°C × 10). R/W for HE/HT/EHS
- H:62 Heating Discharge Set Temperature — Heating discharge setpoint 30–43°C (°C × 10). R/W for HE/HT/EHS
- H:63 Indoor Unit Error Code — 0=No error, 100–999=Error code. Partially covered by module readscript (H:1 outdoor error) but per-unit indoor error not exposed
- H:5 Outdoor Temperature — Outdoor ambient temperature °C × 10. Community-discovered, not in official register table
- H:59 Room Temperature — Current indoor/room temperature °C × 10. Listed as read-only for Indoor/FCU, community confirms availability for HE/HT/EHS on some firmware

## Sources

- MIM-B19N Installation Manual — Modbus register table, wiring, DIP switch addressing
  
  [midsummerwholesale.co.uk](https://midsummerwholesale.co.uk/pdfs/mim-b19n-manual.pdf)
- Extended register map with MessageSet IDs for outdoor/indoor hidden registers
  
  [github.com](https://github.com/ZimKev/MIM-B19n_Modbus)
- Samsung Modbus community integration reference
  
  [github.com](https://github.com/glynhudson)

## 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/)