--- title: "Jablotron 100 Alarm (JA-121T)" description: "Connect the Jablotron 100 alarm to TapHome via the JA-121T RS485 gateway. Monitor sensors and PG outputs, run automations via the JablotronCCU interface." url: "https://taphome.com/en/compatibility/jablotron-ja-121t/" language: en lastmod: 2026-06-05 generator: hugo ai: topics: ["jablotron-integration","rs485-gateway","alarm-system","pg-outputs","home-security"] questions: ["How to connect the Jablotron 100 alarm to TapHome Core?","What is the password format for Jablotron integration in TapHome?","Why must the \"disable alarm\" user option be turned off in the Jablotron settings?","What is the maximum recommended number of PG inputs/outputs for Jablotron?","Can I use the same terminal for Jablotron and other RS485 devices?","Why should I not connect GND when wiring the JA-121T to TapHome?","How to program PG outputs in Jablotron for immediate sensor response?"] --- # Jablotron 100 Alarm (JA-121T) Communication: RS485 - [Jablotron 100+](https://www.jablotron.com) ## Integration guide The Jablotron 100 alarm system exposes an **RS485** gateway (the **JA-121T** bus interface) to securely connect to third-party systems. TapHome speaks the Jablotron protocol natively, so it can read sensor states and PG outputs from the alarm and use them as automation triggers. ![Jablotron 100 system configuration with TapHome over the JA-121T RS485 gateway](https://taphome.com/images/compatibility/jablotron-ja-121t/jablotron-configuration_hu_dd28299f2a745aa8.jpg) > [!NOTE] > **JablotronCCU** is a **native TapHome interface** — there is no template to download or import. After wiring the JA-121T over RS485, add the interface in the app (*Settings → Hardware → Add new interface → Jablotron*). The TapHome Core control unit provides 3 terminals for TapHome Bus or other RS485-based devices. > [!WARNING] > The Jablotron communication protocol has **no protection against packet collisions**. If TapHome queries a sensor at the same moment Jablotron sends an event (e.g. triggered alarm, magnetic contact opened), both messages are lost — so 100% data transfer cannot be guaranteed. Treat the connection as **informative only**. TapHome periodically re-synchronizes the current sensor states, which can occasionally introduce a delay. > [!WARNING] > TapHome must split messages into shorter chunks (max. 100 bytes), which can delay how quickly sensor states appear. Use PG contacts only for information that must arrive as fast as possible, and **do not exceed 30 PG inputs / outputs**. > [!WARNING] > The "disable alarm" option for the user account in the Jablotron unit **must be turned off**. Due to a flaw in the communication protocol, the Jablotron system treats any communication attempt as an automatic alarm deactivation unless this is explicitly turned off. ## Wiring Connect the JA-121T with the TapHome Core. > [!NOTE] > The JA-121T provides **galvanic isolation**, so the GNDs of the Jablotron and TapHome power supplies should **not** be connected. ![Wiring diagram — JA-121T to TapHome Core over RS485 (Terminal 3), no GND connection](https://taphome.com/images/compatibility/jablotron-ja-121t/wiring-diagram_hu_98d8da9caef390e2.jpg) > [!WARNING] > The Jablotron gateway **cannot be combined** with any other device on the same bus terminal. All terminals are RS485 standard, but this provides only electrical compatibility, not data compatibility. ## Configuration ### Add the JablotronCCU interface 1. Open **Settings** → **Hardware**: - Disable **Terminal 3** in TapHome Bus → Terminals - **Add new interface** → **Jablotron** 2. Open **Settings** → **Hardware** → **Jablotron**: - Enable **Terminal 3** - Set the Jablotron password in the format `1 * 2345`, where `1` is the external user ID and `2345` is the password (or whichever format you use). This password must first be created in the Jablotron system. > [!IMPORTANT] > **Do not leave the password field empty.** Without a password, TapHome still reads states but cannot switch PG outputs. The JA-121T sends states on its own, so the states of sensors and PG outputs keep updating even when the password field is empty. Only switching stops working, and it fails silently: the control in the app flips and returns to its previous state a few seconds later. See [Jablotron PG output cannot be switched from TapHome](https://taphome.com/en/troubleshooting/communication/jablotron-pg-not-switching/) for the full fix. ### Program PG outputs in Jablotron To get an immediate response from, for example, a motion sensor, it must be programmed as a **PG output** in Jablotron. Typical use cases: - **Armed status** of the house — to adjust blinds, heating, cooling and ventilation - **Motion sensor** — to turn on corridor lighting when there is motion at night - **Open windows in a zone** — to send a push notification when leaving the house with windows still open In the advanced settings of each PG you can define its device type to adjust the icon and configuration. ### Read-only device types (Reed contacts) ![Read-only device types for Jablotron Reed contacts in TapHome](https://taphome.com/images/compatibility/jablotron-ja-121t/read-only-devices_hu_66221c58bebfc62.jpg) ### Read/write device types (Switches) ![Read/write device types for Jablotron switches in TapHome](https://taphome.com/images/compatibility/jablotron-ja-121t/read-write-devices_hu_e4c69ff01fe53388.jpg) ## Troubleshooting Common issues related to this topic: - [Jablotron PG not switching](https://taphome.com/en/troubleshooting/communication/jablotron-pg-not-switching/) — Sensor and PG output states from Jablotron are read correctly, but PG outputs cannot be switched from TapHome [View all troubleshooting articles](https://taphome.com/en/troubleshooting/)