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