# Read-write memory single Register write instruction(06)

{% hint style="info" %}
This instruction if for memory with 1 register length only, please refer to the [list](/qr/fp-as510-paddle-wheel-flowmeter-manual-en-v1/communication/modbus-rtu-protocol/read-write-memory-list.md).
{% endhint %}

## **Instruction example**

**Format of command (06) from master**

| Byte#                       | 1             | 2             | 3                       | 4                       | 5          | 6          | 7   | 8   |
| --------------------------- | ------------- | ------------- | ----------------------- | ----------------------- | ---------- | ---------- | --- | --- |
| Node ID                     | Slave Address | Function Code | Memory address to write | Memory address to write | Write data | Write data | CRC | CRC |
| <p>Example</p><p>01\~FF</p> | 01            | 06            | 00                      | 00                      | 00         | 01         | 48  | 0A  |

**Description of master command**

This example will change A01 pipe diameter option&#x20;

slave address: 01(address of this flowmeter)

‌function code: 06(Single Register write instruction)

Address of first reading register: 0000(memory address to write)

Write data: 0000 (1" PVC pipe)

‌CRC: C40B (Calculating error correcting code according to CRC algorithm)<br>

**Format of flowmeter response(06)**

| Byte#                       | 1             | 2             | 3                       | 4                       | 5          | 6          | 7   | 8   |
| --------------------------- | ------------- | ------------- | ----------------------- | ----------------------- | ---------- | ---------- | --- | --- |
| Node ID                     | Slave Address | Function Code | Memory address to write | Memory address to write | Write data | Write data | CRC | CRC |
| <p>Example</p><p>01\~FF</p> | 01            | 06            | 00                      | 00                      | 00         | 01         | 48  | 0A  |

**Description of flowmeter response example**

Valid command received. It will output the same command back to master.

‌slave address: 01(address of this flowmeter)

‌function code: 06(Single Register write instruction)

Address of first reading register: 0000(memory address to write)

Write data: 0000 (1" PVC pipe)

‌CRC: C40B (Calculating error correcting code according to CRC algorithm)<br>


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