Overview
All data is mapped to Modbus coils (single-bit registers). The complete coil address space is organized as follows:
| Address Range | Count | Type | Description |
|---|---|---|---|
| 0x0000 – 0x0007 | 8 | Command (R/W) | Arm / Disarm per area (4 areas × 2) |
| 0x0008 – 0x000A | 3 | Command (R/W) | Global Arm / Disarm / Partial |
| 0x000B – 0x002E | 36 | Status (R) | Area status (4 areas × 9) |
| 0x002F – 0x008E | 96 | Status (R) | Detector status (96 detectors) |
| 0x008F – 0x0090 | 2 | Status (R) | System status (AC, Battery) |
| Total | 145 |
Area Command Coils (0x0000 – 0x0007)
These coils allow arming and disarming individual areas. Commands are pulse-type: only the ON edge triggers the action. Coils are automatically reset to 0 after execution.
| Address | Area | Action |
|---|---|---|
| 0x0000 | Area 1 | Arm |
| 0x0001 | Area 1 | Disarm |
| 0x0002 | Area 2 | Arm |
| 0x0003 | Area 2 | Disarm |
| 0x0004 | Area 3 | Arm |
| 0x0005 | Area 3 | Disarm |
| 0x0006 | Area 4 | Arm |
| 0x0007 | Area 4 | Disarm |
Note: When Partition Mode is OFF (global hub mode), only Area 1 coils are active. Use the global command coils for simplified operation.
Global Command Coils (0x0008 – 0x000A)
These coils provide system-wide control commands:
| Address | Command | Description |
|---|---|---|
| 0x0008 | Global Arm | Arm all areas |
| 0x0009 | Global Disarm | Disarm all areas |
| 0x000A | Global Partial | Night Mode (ON = activate, OFF = deactivate) |
Behaviour with Partition OFF (global hub mode)
The three states are mutually exclusive (Armed / Disarmed / Partial). Only the ON edge triggers the action. All commands target the hub globally.
Behaviour with Partition ON (group mode)
- Global Arm: sends an arm command to each configured area individually.
- Global Disarm: sends a disarm command to each configured area and deactivates Night Mode.
- Global Partial: always operates at hub level to activate or deactivate Night Mode.
Area Status Coils (0x000B – 0x002E) — Read Only
Each area has 9 status coils. With 4 areas, this gives 36 status coils in total. A coil value of ON (1) indicates the status is active.
Status Bit Layout per Area
| Offset | Status | Description |
|---|---|---|
| +0 | Disarmed | Area is disarmed and ready |
| +1 | Not used | |
| +2 | Not used | |
| +3 | Armed | Area is armed (total mode) |
| +4 | Partial Armed | Night mode / partial arm active |
| +5 | Fire | Fire alarm active |
| +6 | Not used | |
| +7 | Panic | Panic alarm active |
| +8 | Intrusion | Intrusion alarm active |
Detailed Address Map
| Area | Disarmed | - | - | Armed | Partial | Fire | - | Panic | Intrusion |
|---|---|---|---|---|---|---|---|---|---|
| Area 1 | 0x000B | 0x000C | 0x000D | 0x000E | 0x000F | 0x0010 | 0x0011 | 0x0012 | 0x0013 |
| Area 2 | 0x0014 | 0x0015 | 0x0016 | 0x0017 | 0x0018 | 0x0019 | 0x001A | 0x001B | 0x001C |
| Area 3 | 0x001D | 0x001E | 0x001F | 0x0020 | 0x0021 | 0x0022 | 0x0023 | 0x0024 | 0x0025 |
| Area 4 | 0x0026 | 0x0027 | 0x0028 | 0x0029 | 0x002A | 0x002B | 0x002C | 0x002D | 0x002E |
Detector Status Coils (0x002F – 0x008E) — Read Only
Each detector is mapped to a single coil, supporting up to 96 detectors per gateway. A coil value of ON (1) indicates an alarm or fault condition; OFF (0) indicates normal operation.
| Address | Detector |
|---|---|
| 0x002F | Detector 1 |
| 0x0030 | Detector 2 |
| ... | ... |
| 0x008E | Detector 96 |
Remember that detector statuses are only reported when the system is armed, in night mode, or when individual devices are set to Always Active in the AJAX app (see Zone Reporting Behaviour under Configuring the alarm system).
System Status Coils (0x008F – 0x0090) — Read Only
These coils report the power supply status of the AJAX alarm system. A coil value of ON (1) indicates a fault condition.
| Address | Status | Description |
|---|---|---|
| 0x008F | AC Fault | Main power supply failure |
| 0x0090 | Battery Fault | Battery low or failure |