Read (FB; Prefix filrd)

FUNCTION_BLOCK Read EXTENDS CBM.ETrigToA

This function block reads the file, which was previously opened via ”FILE.Open”. If less characters can be read than specified in ”szBuffer”, the function block returns an active ”xDone” and indicates the current number of characters in ”szSize”. The size of the target memory structure for the bytes to be read and the number of bytes to be read will not be checked.

If the stability of the pointer on the data structures and their contents cannot be guaranteed in case of an online change, an online change must be avoided.

InOut:

Scope	Name	Type	Comment	Inherited from
Input	xExecute	BOOL	Rising edge: Action starts Falling edge: Resets outputs If a falling edge occurs before the function block has completed its action, the outputs operate in the usual manner and are only reset if either the action is completed or in the event of an error. In this case, the corresponding output values (xDone, xError) are present at the outputs for exactly one cycle.	ETrigToA
	xAbort	BOOL	TRUE: Action is stopped immediately and all outputs are reset to their initial values.	ETrigToA
	udiTimeOut	UDINT	Defines the time (µs) after which an FB (e.g. requiring an external acknowledgement) aborts operation due to a timeout with error message.	ETrigToA
Output	xDone	BOOL	TRUE: Action successfully completed	ETrigToA
	xBusy	BOOL	TRUE: Function block active	ETrigToA
	xError	BOOL	TRUE: Error occurred, function block aborts action FALSE: No error	ETrigToA
	xAborted	BOOL	TRUE : Action aborted by user	ETrigToA
Input	hFile	CAA.HANDLE	File handle
	pBuffer	CAA.PVOID	Target address for the first byte to be read; can be retrieved via operator ADR
	szBuffer	CAA.SIZE	Maximum number of bytes to be read; can be retrieved via operator sizeof
Output	eError	ERROR	Local library error ID (0: no error; 5101: time out)
Output	szSize	CAA.SIZE	Current number of successfully read bytes; this value is already valid before xDone has been set