--- title: "Samsung MIM-B19N (IU)" description: "Samsung MIM-B19N Modbus RTU gateway for air conditioning indoor units (cassette, wall, 360) with R1/R2 Samsung bus connection." url: "https://taphome.com/en/compatibility/samsung-mim-b19n-iu/" language: en lastmod: 2026-10-08 generator: hugo ai: topics: ["modbus-rtu","air-conditioning","rs485","dip-switch","samsung-nasa","cassette","wall-unit","360-cassette","wind-free"] questions: ["How to integrate Samsung air conditioning indoor units with TapHome?","What does the Samsung MIM-B19N IU TapHome template control?","How to connect Samsung MIM-B19N via RS-485 to TapHome for AC control?","How to configure multi-unit addressing for Samsung indoor units via MIM-B19N?","What is the difference between the Samsung MIM-B19N IU and EHS templates?","How to control Samsung 360 cassette airflow direction via TapHome?","How to enable Samsung Wind-Free mode via TapHome Modbus?"] --- # Samsung MIM-B19N (IU) 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 air conditioning indoor units -- cassettes, wall units and 360 cassettes -- to TapHome via RS-485. This template is specifically designed for **indoor AC units (IU)**, not heat pumps. For Samsung EHS/HE/HT heat pump units, use the [Samsung MIM-B19N (EHS)](https://taphome.com/en/compatibility/samsung-mim-b19n-ehs/) template. For gateway-level outdoor unit monitoring, see the [Samsung MIM-B19N (GW)](https://taphome.com/en/compatibility/samsung-mim-b19n-gw/) template. The gateway translates between the Samsung R1/R2 internal bus protocol and standard Modbus RTU, exposing room temperature control, fan speed, operation modes, airflow direction and the Wind-Free function as holding registers. Each MIM-B19N can manage up to 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 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 (cassette, wall, 360) ``` ## 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 | Location | ON value | |--------|----------|----------| | SW4-1 | DIP | 128 | | SW4-2 | DIP | 64 | | SW5-1 | DIP | 32 | | SW5-2 | DIP | 16 | | SW1 | Rotary | 0--15 (hex) | **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 (IU variable) For systems with multiple indoor units, register addresses shift by 50 per unit using the **IU variable** formula: `base = 50 + IU * 50`. | Indoor unit | IU value | Base register | Power register | |-------------|----------|---------------|----------------| | Unit 0 (first) | 0 | 50 | H:52 | | Unit 1 | 1 | 100 | H:102 | | Unit 2 | 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 IU variable value in the module scripts. ## Device capabilities ### Room temperature control - **Room Temperature** (H:base+9 read / H:base+8 write) -- current room temperature and setpoint control with °C x 10 conversion. Setpoint ranges: Cooling 18--30 °C, Heating 16--30 °C ### Unit power and operation mode - **Power ON/OFF** (H:base+2) -- turns the indoor unit on or off - **Operation Mode** (H:base+3) -- selects Auto, Cool, Dry, Fan, or Heat mode - **Fan Speed** (H:base+4) -- selects Auto, Low, Medium, or High ### Airflow control - **Vertical Air Flow** (H:base+5) -- enables or disables the vertical vane swing - **360 Air Flow Direction** (H:base+31) -- controls the 360 cassette vane position: Off, Spot, Mid, Wide, Swing, or Individual Control. Only applicable to Samsung 360 cassette units ### Wind-Free function - **Wind Free** (H:base+30) -- enables Samsung Wind-Free cooling mode, which disperses air through micro-holes instead of direct airflow. Values: 0=Off, 9=WindFree. Only available on Wind-Free compatible indoor units ### Service diagnostics The module exposes three service attributes for system monitoring: - **Communication Status** (H:base+0) -- bitfield showing: Exist, Type OK, Ready, Communication error - **Remote Control Restriction** (H:base+14) -- shows whether the remote controller is locked - **Wind-Free Function Status** (H:base+30) -- shows whether Wind-Free is active (None, WindFree, Ignored) One service action is available: - **Clear Filter Alarm** (H:base+6) -- resets the filter cleaning reminder The module ReadScript monitors the filter alarm register (H:base+6) and the indoor unit error code (H:base+13), reporting them as warnings and errors in TapHome. ### Additional capabilities The MIM-B19N register map also exposes per-unit registers for discharge temperature (H:base+10), quiet mode control (H:base+28), away function (H:base+29), and remote control restriction write (H:base+14). These can be added in a future template update. > [!TIP] > This template covers **air conditioning indoor units** only. If you have Samsung EHS, HE, or HT heat pump units connected to the same MIM-B19N gateway, use the separate [Samsung MIM-B19N (EHS)](https://taphome.com/en/compatibility/samsung-mim-b19n-ehs/) template for those units. ## 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:base+0) shows bits 0--2 all set to 1 (Exist + Type OK + Ready) 2. Check that Remote Control Restriction is not active (H:base+14 = 0x0000) 3. Verify the indoor unit IU address is within range (0--47) 4. Allow at least 10 ms between consecutive Modbus read/write commands ### 360 Air Flow Direction not responding 1. Confirm the indoor unit is a Samsung 360 cassette model -- this register is only available on 360 cassettes 2. Verify the multi-value values match the installed unit's capabilities 3. Check the template is using the correct IU variable for the target unit ## Available devices Samsung MIM-B19N Module Service Attributes | | | |----------------------------|-------------------------------------------------------------------------------------------| | Communication Status | reads H:base+0 (UInt16); bitfield: b0=Exist, b1=Type OK, b2=Ready, b3=Communication error | | Remote Control Restriction | reads H:base+14 (UInt16); 0x0000=No restriction, other=Restriction active | | Wind-Free Function Status | reads H:base+30 (UInt16); 0=None, 9=WindFree, other=Ignored | Service Actions | | | |--------------------|------------------------------------------------| | Clear Filter Alarm | writes H:base+6 (UInt16); 1=Clear filter alarm | 360 Air Flow Direction Multi-value Switch Controls the 360 cassette vane position — only applicable to Samsung 360 cassette units Register: H:base+31 Int16 mapped Values / States: Spot · Mid · Wide · Swing · Individual Control Fan Speed Multi-value Switch Controls the indoor unit fan speed Register: H:base+4 UInt16 numeric Values / States: Auto · Low · Medium · High Operation Mode Multi-value Switch Selects the AC operation mode Register: H:base+3 UInt16 numeric Values / States: Auto · Cool · Dry · Fan · Heat Power ON/OFF Switch Turns the indoor AC unit on or off Register: H:base+2 Bool Values / States: ON · OFF Room Temperature Thermostat Current room temperature and setpoint control Register: H:base+9 → H:base+8 Int16 Unit: °C numeric Vertical Air Flow Switch Enables or disables the vertical vane swing Register: H:base+5 Bool Values / States: ON · OFF Wind Free Switch Samsung Wind-Free cooling mode — disperses air through micro-holes instead of direct airflow Register: H:base+30 UInt16 numeric Values / States: ON · OFF **Connection:** Modbus RTU • 9600 baud• 8E1 • Slave ID: $\[SlaveId] Possible improvements (6) - H:base+6 Filter-Cleaning Reminder — 0=No alarm, 1=Filter alarm present. Read via module readscript (ADDWARNING) but not exposed as device. Indoor/ERV/FCU only - H:base+10 Discharge Temperature — Discharge temperature °C × 10. Available for Indoor units. Read-only - H:base+13 Indoor Unit Error Code — 0=No error, 100–999=Error code. Read via module readscript (ADDERROR) but not exposed as device - H:base+14 Remote Control Restriction (write) — Write: 0x0000=No restriction, 0x6363=Restriction. Read exposed as service attribute but write not exposed as service action - H:base+28 Quiet Control — 0=Silence Off, 1=Silence On. Available for Indoor units but not implemented in template - H:base+29 Away Function — 0=Outing Off, 1=Outing On. Available for Indoor units but not implemented in template ## 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/)