# String read in RS485/RS232

YuDash devices use the built-in **Modbus RS485/RS232 interface** to receive ASCII/text data from serial instruments such as weather sensors, analyzers, or weighing systems. The interface is defined as custom Modbus registers, for a flexible **raw text inputs** parsing. 

The input string is defined with modbus register value of 60000 range.

mbReg: 60ABC:  ABC represent maximum bytes to be read from the input stream.

varType:  defines the format and handline of input read.

The input can be treated as String (ASCII) or HEX data:

1. String: Input treated as ASCII/text data. This is applicable for varType range 50-54.
2. Hex: The input is treated as HEX data. A two character output in capital letters (followed by a space) is written for every input hex byte. This is applicable for varType range 55-59.

<table><thead><tr><th width="119">varType</th><th width="102">Input Type</th><th>Input read behavior</th></tr></thead><tbody><tr><td>50</td><td>String</td><td>Terminate input read at new line (\n, or \r). Flush balance input buffer after read.</td></tr><tr><td>51</td><td>String</td><td>Do not terminal at newline. Read all input bytes based on mbReg.</td></tr><tr><td>52</td><td>String</td><td>Terminate read at new line (\n, or \r). Do not flush buffer after serial read.</td></tr><tr><td>55</td><td>Hex</td><td>Terminate input read at new line (\n, or \r). Flush balance input buffer after read. </td></tr><tr><td>56</td><td>Hex</td><td>Do not terminal at newline. Read all input bytes based on mbReg.</td></tr><tr><td>57</td><td>Hex</td><td>Terminate read at new line (\n, or \r). Do not flush buffer after serial read.</td></tr></tbody></table>

#### Sample Modbus Slave settings for String input

* **slaveID and mbRegCnt:** These value remain 1 as default.&#x20;
* **varName**: The output variable name (**voltage\_string**) in which output string will be stored for further processing.
* mbReg: 60050. A register number >6000 represent string input read. 50 represents maximum 50 bytes to be read from the input. This can be set based on estimated text input line from the instrument.
* varType: 50.  50 means we treat input as string (ASCII), terminate reading at a newline and flush the baalnce input buffer. This will be the typical setting for most of the use-cases.&#x20;

```json
// modbus settings for RS485 string read
  "modBusSlaves": [
    {
      "slaveID": "1",
      "mbRegCnt": 1,
      "mbArray": [
        {
          "varName": "voltage_string",
          "mbReg": "60050",
          "varType": "50",
          "varFactor": "1"
        }
      ]
    }
  ],
```


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