> For the complete documentation index, see [llms.txt](https://inacks.gitbook.io/is4310-wiki/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://inacks.gitbook.io/is4310-wiki/datasheet/memory-description/holdx-registers.md).
# HOLDx Registers
HOLDx Registers are Modbus Holding Registers available for use in your application. They can be accessed (read and written) by both the Modbus Master and the Microcontroller. The access can be individually or in block. Each register is 16 bits long and they are volatile RAM.
If your product is a sensor, these registers are typically written by the Microcontroller with sensed data, such as pressure, temperature, or humidity, and read by the Modbus Master.
If the product is an actuator, these registers are usually written by the Modbus Master with control data, such as relay states (on/off), motor speed, or solenoid valve positions, and read by the Microcontroller.
These registers can also serve as a bidirectional data exchange point, allowing both the Modbus Master and the Microcontroller to read and write data.
---
# 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://inacks.gitbook.io/is4310-wiki/datasheet/memory-description/holdx-registers.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.