---
title: "Samsung MIM-B19N (Gateway)"
description: "Samsung MIM-B19N Modbus RTU gateway diagnostic module for TapHome. Monitors error registers, outdoor unit errors, and discovers all 48 indoor unit slots."
url: "https://taphome.com/en/compatibility/samsung-mim-b19n-gw/"
language: en
lastmod: 2026-10-08
generator: hugo
ai:
  topics: ["modbus-rtu","gateway","rs485","dip-switch","samsung-nasa","diagnostics","error-monitoring"]
  questions: ["How to set up Samsung MIM-B19N gateway diagnostics in TapHome?","What is the difference between Samsung MIM-B19N GW, EHS and IU templates?","How does the Samsung MIM-B19N Units Found service attribute work?","How to monitor Samsung MIM-B19N error registers in TapHome?","What unit types can the Samsung MIM-B19N gateway detect?","How to diagnose Samsung R1/R2 bus communication issues with TapHome?"]
---

# Samsung MIM-B19N (Gateway)

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)

This is the **diagnostic module** for the Samsung MIM-B19N Modbus RTU gateway. It monitors the gateway error register and outdoor unit error code, and provides an indoor unit discovery service that scans all 48 IU slots with automatic type detection.

This template does **not** contain controllable devices. For controlling indoor units, use the [Samsung MIM-B19N (IU)](https://taphome.com/en/compatibility/samsung-mim-b19n-iu/) template. For heat pump control (EHS/HE/HT units), use the [Samsung MIM-B19N (EHS)](https://taphome.com/en/compatibility/samsung-mim-b19n-ehs/) template.

## Hardware connection

The hardware connection is identical for all three MIM-B19N templates. See the [Samsung MIM-B19N (EHS)](https://taphome.com/en/compatibility/samsung-mim-b19n-ehs/) page for full wiring instructions, DIP/rotary switch addressing, and RS-485 configuration.

### Quick reference

- **Power supply:** DC 12 V from CN12 on outdoor unit main board
- **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)

## Module capabilities

### Error monitoring

The module ReadScript continuously monitors two registers:

- **H:0 -- Error register** (bitfield) -- detects three error conditions:
  - Bit 0: Address error
  - Bit 1: R1/R2 communication error
  - Bit 2: Tracking error
- **H:1 -- Outdoor unit error code** -- reports the outdoor unit error code number; any non-zero value triggers an error in TapHome

These errors appear in the TapHome module status, allowing immediate notification when the gateway or outdoor unit encounters a problem.

### Units Found (service attribute)

The "Units Found" service attribute performs a discovery scan across all 48 indoor unit slots. For each slot, it reads:

- **H:base+0** -- Communication status bitfield (Exist, Type OK, Ready, Communication error)
- **H:base+1** -- Unit type register

Where `base = 50 + IU x 50` (IU = 0..47).

The attribute decodes the unit type byte into a human-readable label:

| Type byte range | Detected unit type |
|----------------|--------------------|
| 0x6E | HE |
| 0x78 | HT |
| 0x73--0x75 | EHS |
| Upper byte = 10 | FCU |
| 0x64--0x65 | ERV |
| 0x6C | ERV+ |
| 0x5A--0x63 | AHU |
| 0x8C--0x95 | Chiller |
| 0xA0--0xA9 | FCU kit |
| 0xFFFF | Not defined |

The output lists each found unit with its slot index, detected type, and status flags -- for example: `IU 0 Exist (EHS), Type OK, Ready`.

## When to use this template

Use this gateway diagnostic template when you need to:

- **Monitor gateway health** -- track R1/R2 bus errors and outdoor unit faults
- **Discover connected units** -- identify how many and what type of indoor units are on the Samsung bus before configuring control templates
- **Diagnose installation issues** -- verify that all expected units are found and in "Ready" state

After discovery, import the appropriate control template for each unit type:

- [Samsung MIM-B19N (EHS)](https://taphome.com/en/compatibility/samsung-mim-b19n-ehs/) -- for HE, HT and EHS heat pump units
- [Samsung MIM-B19N (IU)](https://taphome.com/en/compatibility/samsung-mim-b19n-iu/) -- for indoor air conditioning units (cassette, wall-mounted and 360 cassette)

## Troubleshooting

### No units found in discovery

1. Verify the MIM-B19N is powered (DC 12 V from CN12 on outdoor unit)
2. Check that indoor units are powered on and connected to the Samsung F1/F2 bus
3. Wait up to 10 minutes for tracking to complete after power-on
4. If the error register shows a tracking error (bit 2), reset the MIM-B19N module

### Error register shows R1/R2 communication error

1. Check the F1/F2 bus wiring between the MIM-B19N and the outdoor unit
2. Verify the MIM-B19N is installed on the correct outdoor unit PCB connector
3. Check for bus conflicts with other Samsung accessories

### No Modbus communication with TapHome

1. Check RS-485 wiring polarity (A to A+, B to B-)
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

## 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/)