> For the complete documentation index, see [llms.txt](https://support.powerio.com/hub/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://support.powerio.com/hub/codesys-hvac/en/hvac-modbus-library/functionblocks/generic/modbusclient_rtu.md).

# ModbusClient\_RTU

## `ModbusClient_RTU` (FB) <a href="#modbusclient_rtu-fb" id="modbusclient_rtu-fb"></a>

`FUNCTION_BLOCK` ModbusClient\_RTU EXTENDS ModbusClientBase

### **Representation**

<figure><img src="/files/10aa9f6ba22b73266a1cf8f3d2befde8a8fbc5cc" alt=""><figcaption></figcaption></figure>

InOut:

| Scope       | Name                    | Type                      | Initial                                   | Comment                                                                                             | Inherited from   |
| ----------- | ----------------------- | ------------------------- | ----------------------------------------- | --------------------------------------------------------------------------------------------------- | ---------------- |
| Output      | `xConnected`            | `BOOL`                    |                                           | TRUE if connection has been established                                                             | ModbusClientBase |
| Output      | `xLicenceValid`         | `BOOL`                    |                                           | TRUE if a valid licence was found                                                                   | ModbusClientBase |
| Input       | `xResError`             | `BOOL`                    | FALSE                                     | <p>Input for resetting the error outputs (eErrorCode,<br>byErrorUnitID) (on every rising edge)</p>  |                  |
| Output      | `iSerialPortFb`         | `INT`                     | 0                                         | Feedback of the number of the serial interface                                                      |                  |
| Output      | `eBaudrateFb`           | `SysCom.SYS_COM_BAUDRATE` | SysCom.SYS\_COM\_BAUDRATE.SYS\_BR\_4800   | <p>Feedback of the transmission speed of the serial<br>interface</p>                                |                  |
| Output      | `eParityFb`             | `SysCom.SYS_COM_PARITY`   | SysCom.SYS\_COM\_PARITY.SYS\_NOPARITY     | Feedback of the parity per `BYTE` of the serial interface                                           |                  |
| Output      | `eStopBitsFb`           | `SysCom.SYS_COM_STOPBITS` | SysCom.SYS\_COM\_STOPBITS.SYS\_ONESTOPBIT | <p>Feedback of the number of stop bits per byte of the serial<br>interface</p>                      |                  |
| Output      | `eState`                | Client\_RTU\_StateCode    | Client\_RTU\_StateCode.IDLE               | Current state of the state machine                                                                  |                  |
| Output      | `byErrorUnitID`         | `BYTE`                    | 0                                         | Unit ID of the last error (0 = no device)                                                           |                  |
| Output      | `xError`                | `BOOL`                    | FALSE                                     | <p>Display of the error state (FALSE = no error, TRUE =<br>error)</p>                               |                  |
| Output      | `eErrorCode`            | Client\_RTU\_ErrorCode    | Client\_RTU\_ErrorCode.NO\_ERROR          | Display of the cause of the last error                                                              |                  |
| Input Const | `eStopBits`             | `SysCom.SYS_COM_STOPBITS` | SysCom.SYS\_COM\_STOPBITS.SYS\_ONESTOPBIT | <p>Specification of the number of stop bits per byte of the serial<br>interface</p>                 |                  |
| Input Const | `eParity`               | `SysCom.SYS_COM_PARITY`   | SysCom.SYS\_COM\_PARITY.SYS\_NOPARITY     | Specification of the parity per byte of the serial interface                                        |                  |
| Input Const | `eBaudrate`             | `SysCom.SYS_COM_BAUDRATE` | SysCom.SYS\_COM\_BAUDRATE.SYS\_BR\_38400  | <p>Specification of the transmission speed of the serial<br>interface</p>                           |                  |
| Input Const | `iSerialPort`           | `INT`                     | 2                                         | Specification of the number of the serial interface                                                 |                  |
| Input Const | `tTimeCheckComPort`     | `TIME`                    | TIME#5s0ms                                | <p>Time interval between two checking operations for the serial<br>interface in idle state</p>      |                  |
| Input Const | `tTimeoutDeviceReceive` | `TIME`                    | TIME#1s0ms                                | <p>Timeout period for monitoring the response telegram<br>(receiving)</p>                           |                  |
| Input Const | `tTimeoutDeviceSend`    | `TIME`                    | TIME#1s0ms                                | <p>Timeout period for monitoring the request telegram<br>(sending)</p>                              |                  |
| Input Const | `tTimeoutComConnect`    | `TIME`                    | TIME#1s0ms                                | <p>Timeout period for monitoring the establishment of the<br>connection to the serial interface</p> |                  |


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