# CO2 auto-zero period

### S**et CO2 auto-zero period**

Default auto-zero period, after the factory auto-zeroing, is 192 hours (8 days). During this period the lowest measured CO2 value is accepted as 400ppm and the auto-zero value is obtained automatically. If The period is 0, automatic auto-zero function is disabled, but the obtained or set with command auto-zero value is still used internally.

The command is described in Table 19.

| **Byte inde** | **Hex Velue** | **Meaning**                                 |
| ------------- | ------------- | ------------------------------------------- |
| 0             | 2A            | The command code.                           |
| 1             | 48            | Auto-zero period in hours. 0x48 = 72 hours. |

*Table 19*

**Example command:** 0x2A48 – The server sets CO2 auto-zero period to 72 hours.

### **Get CO2 auto-zero period**

| **Byte index** | **Sent request**   | **Received response**                             |
| -------------- | ------------------ | ------------------------------------------------- |
| 0              | 2B – Command code. | 2B – The command code.                            |
| 1              |                    | 48 –  Auto-zero period in hours. 0x48 = 72 hours. |

*Table 20*

**Example command sent from server:** 0x2B;

**Example command response:** 0x2B48 =>  CO2 auto-zero period is 72 hours.


---

# Agent Instructions: 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:

```
GET https://docs.mclimate.eu/mclimate-lorawan-devices/devices/mclimate-co2-sensor-and-notifier-lorawan/co2-sensor-lorawan-device-communication-protocol/co2-auto-zero-period.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
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.