> For the complete documentation index, see [llms.txt](https://help.security.gallagher.com/knowledge-hub/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.security.gallagher.com/knowledge-hub/products/cc-hardware/input-and-output-io-devices/io-devices-hbus.md).

# HBUS I/O devices

Identify current HBUS I/O devices, power requirements, and cable-run limits.

Identify currently supported HBUS I/O hardware. Use the variants and topology rules to plan an installation.

### Overview

Gallagher Security provides I/O devices that connect to a controller through the proprietary HBUS protocol.

HBUS units are uniquely serialized. When connected, the controller identifies and configures each device.

> ⚠️ **If an HBUS I/O device is replaced, Command Centre must be configured to recognize the replacement part.** Otherwise it cannot communicate with the Controller.

### Variants

<table><thead><tr><th width="156">Part Number</th><th width="455.2000732421875">Description</th><th>Install Note</th></tr></thead><tbody><tr><td>C300680</td><td>HBUS 8 In Board</td><td><a href="https://media.gallagher.com/asset/9b03e3d4-f047-4343-8b6d-6a66215ca9a9/3E3475-Install-Note-HBUS-8-IN-Board.pdf">3E3475</a></td></tr><tr><td>C300684</td><td>HBUS 8 In 4 Out Board</td><td><a href="https://media.gallagher.com/asset/354e80ec-ccb3-4d8c-a51f-ba9851f6c367/3E3474-Install-Note-HBUS-8-IN-4-OUT-Board.pdf">3E3474</a></td></tr><tr><td>C300688</td><td>HBUS 16 In 16 Out Board</td><td><a href="https://media.gallagher.com/asset/fba7160e-249b-4d7c-b300-ab3de90729ed/3E3473-Install-Note-HBUS-16-In-16-Out-Board.pdf">3E3473</a></td></tr><tr><td>C300660</td><td>HBUS 8 In 2 Out Door Module</td><td><a href="https://media.gallagher.com/asset/6cd63112-b329-4dbb-afdf-dc57d19c9908/3E3472-Install-Note-HBUS-8-In-2-Out-Door-Module.pdf">3E3472</a></td></tr><tr><td>C300665</td><td>HBUS 4 In 2 Out Door Module - Wiegand</td><td><a href="https://media.gallagher.com/asset/6b332bb2-8ade-4564-a7c6-a53143811188/3E4597-Install-Note-HBUS-4-In-2-Out-Door-Module-Wiegand.pdf">3E4597</a></td></tr><tr><td>C300698</td><td>HBUS 8 Port Hub</td><td><a href="https://media.gallagher.com/asset/f80c4a2c-5bcb-4a60-86b6-a75b5bf2acfe/3E4465-Install-Note-HBUS-8-Port-Hub.pdf">3E4465</a></td></tr></tbody></table>

Power differs across the range. The 8 In and 8 In 4 Out boards and both door modules are HBUS-powered. The **HBUS 16 In 16 Out Board requires a separate external 12 V DC supply**, and both hubs require separate external power.

> 📎 **Part-number note:** the 4 In 2 Out Wiegand door module is **C300665** (install note 3E4597). **C300660** is a different part, the HBUS 8 In 2 Out Door Module (install note 3E3472).

### Topology rules

* Maximum 24 HBUS units per cable run.
* Maximum cable distance 500 m from the Controller 7000. This requires **Command Centre vEL9.40 or later**.
* Topology must be **daisy-chain only**. T-junctions and star topologies are not permitted between HBUS devices.
* End devices on each cable run must be terminated with 120 ohm resistance.
* Ground shielded cable at the controller end only.

#### Recommended cables

| Cable                                | Format                                   | Max distance (data only) | Max distance (power + data) |
| ------------------------------------ | ---------------------------------------- | ------------------------ | --------------------------- |
| CAT 5e or better                     | 4 twisted pair, 2 x 0.2 mm² (24 AWG)     | 500 m                    | 50 m                        |
| Belden 9842 (shielded)               | 2 twisted pair, 2 x 0.2 mm² (24 AWG)     | 500 m                    | 50 m                        |
| SEC472                               | 4 x 0.2 mm² untwisted (24 AWG)           | 400 m                    | 50 m                        |
| SEC4142                              | 4 x 0.4 mm² untwisted (21 AWG)           | 400 m                    | 100 m                       |
| C303900/C303901 Gallagher HBUS Cable | 2 twisted pair data + 2 x 0.75 mm² power | 500 m                    | 200 m                       |

### Related documents

* [HBUS I/O Devices Datasheet](https://media.gallagher.com/asset/48be7e59-0d06-493b-9eec-c89180143cde/HBUS_IO_Devices_Datasheet.pdf)


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation by asking a question.

Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:

```
GET https://help.security.gallagher.com/knowledge-hub/products/cc-hardware/input-and-output-io-devices/io-devices-hbus.md?ask=<question>&goal=<user_goal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.