# 讀寫型記憶體雙Register寫入指令(30)

{% hint style="info" %}
限使用在 Register 長度為 2 的記憶體，請參考[列表](/qr/fp-as510-paddle-wheel-flowmeter-manual-chinese-v2/communication/modbus-rtu-protocol/read-write-memory-list.md)。
{% endhint %}

| Register 位置 | 記憶體內容          | 資料型式     |
| ----------- | -------------- | -------- |
| 0001        | scale factor   | float 32 |
| 0304        | upper limit    | float 32 |
| 0306        | lower limit    | float 32 |
| 030B        | Total Target   | float 32 |
| 0406        | 0mA/4mA Value  | float 32 |
| 0408        | 20mA Value     | float 32 |
| 040B        | 0mA/4mA Adjust | float 32 |
| 040D        | 20mA Adjust    | float 32 |

## 指令範例

### 控制端發指令(30)格式

| Byte#      | 1             | 2             | 3        | 4        | 5    | 6    | 7    | 8    | 9   | 10  |
| ---------- | ------------- | ------------- | -------- | -------- | ---- | ---- | ---- | ---- | --- | --- |
| Node ID    | Slave Address | Function Code | 寫入的記憶體地址 | 寫入的記憶體地址 | 寫入資料 | 寫入資料 | 寫入資料 | 寫入資料 | CRC | CRC |
| 範例內容01\~FF | 01            | 30            | 00       | 01       | 40   | 20   | 00   | 00   | 98  | 0E  |

#### 控制端發訊範例說明

這個範例會改變 A02 Scale Factor 數值變成 2.50

slave address: 01(本流量計地址)

function code: 30(雙Register寫入指令)

讀取數據的啟始地址: 0001(要寫入記憶體地址)

寫入資料: 40 20 00 00(改變 A02 Scale Factor 數值變成 2.50)

CRC:  98 0E(依 CRC 算法計算出的糾錯碼)

### 流量計回覆(30)格式

| Byte#      | 1             | 2             | 3        | 4        | 5    | 6    | 7    | 8    | 9   | 10  |
| ---------- | ------------- | ------------- | -------- | -------- | ---- | ---- | ---- | ---- | --- | --- |
| Node ID    | Slave Address | Function Code | 寫入的記憶體地址 | 寫入的記憶體地址 | 寫入資料 | 寫入資料 | 寫入資料 | 寫入資料 | CRC | CRC |
| 範例內容01\~FF | 01            | 30            | 00       | 01       | 40   | 20   | 00   | 00   | 98  | 0E  |

#### 流量計回覆範例說明

寫入指令符合格式，會將收到的控制端指令回傳給 Master

slave address: 01(本流量計地址)

function code: 30(雙Register寫入指令)

讀取數據的啟始地址: 0001(要寫入記憶體地址)

寫入資料: 40 20 00 00(改變 A02 Scale Factor 數值變成 2.50)

CRC:  98 0E(依 CRC 算法計算出的糾錯碼)


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