> For the complete documentation index, see [llms.txt](https://help.security.gallagher.com/smb/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/smb/installing-gallagher-smb/installing-the-hardware/connect-inputs-and-outputs.md).
# Connect Inputs & Outputs
Gallagher HBUS I/O Devices provide flexible, cost effective, secure input and output expansion options, and shared cabling with other HBUS devices. The HBUS communications protocol is based on the RS485 standard and allows each HBUS I/O Board to communicate with the Gallagher Controller over a distance of up to 500 m (1640 ft) at a speed of 1 Mb/s.
The following I/O Boards are compatible with the SMB Solution:
* Gallagher 8In Board
* Gallagher 8In 4Out Board
* Gallagher 16In 16Out Board
**Key Benefits**
* Multiple boards can be daisy chained together along the same cable run
* Unique identifier for all field devices
* IT grade authentication and encryption levels to prevent data tampering
**Variable end of line resistance**
* Configurable end of line resistance is supported for all Gallagher HBUS I/O boards.
**Controlling inputs and outputs**
* Making no high-level decisions, the HBUS I/O boards monitor the state of the balanced inputs and switches the output relays as instructed by the controller.
* All devices connected to a single I/O board must share the same physical resistor value, (i.e. individual devices cannot have different resistors, unless assigned to different boards). You can change the resistance value for an I/O board or add boards to the system if required, within the SMB Installer Portal.
* The HBUS 16In 16Out board can be utilized with the SMB Kit to expand the solution
---
# 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 dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:
```
GET https://help.security.gallagher.com/smb/installing-gallagher-smb/installing-the-hardware/connect-inputs-and-outputs.md?ask=&goal=
```
`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.
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.
