ModbusRequest (FB)¶

FUNCTION_BLOCK ModbusRequest

InOut:

Scope	Name	Type	Initial	Comment
Input	`hComPort`	`RTS_IEC_HANDLE`
	`xExecute`	`BOOL`		Triggers sending a Modbus request on a rising edge following the PLCopen specification
	`xAbort`	`BOOL`		Aborts the current request if TRUE
	`usiSlaveAddr`	`USINT`		Slave address, range 1..247
	`uiFunctionCode`	`UINT`	3	Modbus function code
	`uiReadOffset`	`UINT`	0	Address offset to start reading from, range 0..65535
	`uiReadLen`	`UINT`	1	Number of registers to read, range 1..125
	`uiWriteOffset`	`UINT`	0	Address offset to start reading from, range 0..65535
	`uiWriteLen`	`UINT`	1	Number of registers to write, range 1..121
	`tTimeout`	`TIME`		Timeout for the request in ms
	`pWriteBuf`	POINTER TO BYTE		Pointer to a buffer holding the data to be send to the Slave
	`pReadBuf`	POINTER TO BYTE		Pointer to a buffer for writing the data received from a Slave
	`transmission`	MB_Transmission		transmission type (RTU or ASCII)
Output	`xBusy`	`BOOL`		Is TRUE as long as a request is in progress
	`xDone`	`BOOL`		Is TRUE if a request finished successfully
	`xError`	`BOOL`		Is TRUE if a request finished unsuccessfully
	`xAborted`	`BOOL`		Is TRUE after a request in progress has been aborted by “xAbort”
	`byModbusErrorCode`	`BYTE`		Specifies the current error as defined in the “MB_ErrorCodes” enumeration