LGF_ShiftRegister (FB / V1.0.3)

Author: Siemens Digital Industry Support

Short description

The Function represents a shift register for any kind of Datatype (using variant).
It is possible to shift the elements in the array at bufferRegister to the left (index array[n]:=array[n+1]) or right (index array[n]:=array[n-1]).
It could be used for material tracking trough a machine or a process, e.g. for a rotary indexing table.

Note: As this is a real shift operation, it may cause some runtime effects while using big array sizes to move at the input bufferRegister.; Please consider that a FIFO or LIFO storage, based on indexes, could be used as well for most applications.

Block Interface


Bool	shiftLeft	error	Bool
Bool	shiftLeft	error	Bool
Bool	shiftRight	status	Word
Bool	shiftRight	status	Word
UInt	shiftRange	subFunctionStatus	Word
UInt	shiftRange	subFunctionStatus	Word
Bool	clear
Bool	clear
Bool	fill
Bool	fill
Variant	initialItem
Variant	initialItem
Variant	bufferRegister		Variant
Variant			Variant

Input parameter

Identifier	Data type	Default value	Description
shiftLeft	Bool	FALSE	Rising edge: Elements in the array `bufferRegister` shifted left. Elements moved from index `N` to `N - 1`. The element at index `N = 0`is overwritten
shiftRight	Bool	FALSE	Rising edge: Elements in the array `bufferRegister` shifted right. Elements moved from index `N` to `N + 1`. The element at index `N = lastIndex` is overwritten
shiftRange	UInt	1	Number of places to be shifted in the `bufferRegister` input array
clear	Bool	FALSE	Clear buffer elements in `bufferRegister` with `initalItem`
fill	Bool	FALSE	Overwrite buffer elements after shift operation. * `shiftLeft` - the most right element/s * `shiftRight` - the most left element/s overwritten by `initalItem`.
initialItem	Variant	---	Value with which the array at input `bufferRegister` is initialized (usually the default value)

Output parameter

Identifier	Data type	Description
error	Bool	FALSE: No error TRUE: An error occurred during the execution of the FB
status	Word	16#0000-16#7FFF: Status of the FB 16#8000-16#FFFF: Error identification (see following Table)
subFunctionStatus	Word	Status or return value of called FB's, FC's and system blocks

In/Out parameter

Identifier	Data type	Description
bufferRegister	Variant	Buffer / Register memory as ARRAY, which keeps the data. The data in the register is shifted left or right depending on the command.

Status & Error codes

Code / Value	Identifier / Description
16#0000	STATUS_NO_ERROR Status: Execution finished without errors
16#7000	STATUS_NO_CURRENT_JOBS Status: No current jobs, initial state
16#8200	ERR_NO_ARRAY Error: No array is present at the input `bufferRegister`
16#8201	ERR_CLEARING_WITHOUT_INITIAL_ITEM Error: Claering `bufferRegister` without an `initialItem` is not possible.
16#8202	ERR_FILL_WITHOUT_INITIAL_ITEM Error: Option `fill` the buffer after shift operation without an `initialItem` is not possible.
16#8203	ERR_WRONG_TYPE_INITIAL_ITEM Error: The data type of the input `initialItem` does not correspond to the data type of the array at the InOut parameter `bufferRegister`.
16#8401	ERR_MORE_THAN_ONE_COMMAND Error: More than one command present at the same time. Only one of the inputs `shiftLeft`, `shiftRight` or `clear` is allowed.
16#8402	ERR_IN_SHIFT_RANGE Error: The value at `shiftRange` must not exceed the maximum size of the Array at `bufferRegister`.
16#8610	ERR_CLEAR_BUFFER Error: While clearing buffer in block `MOVE_BLK_VARIANT``. Check `subFunctionStatus` code.
16#8611	ERR_SHIFT_BUFFER_LEFT Error: While shift buffer left in block `MOVE_BLK_VARIANT` - check `subFunctionStatus` code
16#8612	ERR_SHIFT_BUFFER_LEFT_FILL Error: While fill buffer after shift left in block `MOVE_BLK_VARIANT` - check `subFunctionStatus` code
16#8622	ERR_SHIFT_BUFFER_RIGHT Error: While shift buffer right in block `MOVE_BLK_VARIANT` - check `subFunctionStatus` code
16#8622	ERR_SHIFT_BUFFER_RIGHT_FILL Error: While fill buffer after shift right in block `MOVE_BLK_VARIANT` - check `subFunctionStatus` code

Change log

Version & Date		Change description
	01.00.00	Siemens Industry Online Support
	03.07.2018	First released version
	03.00.00	Simatic Systems Support
	09.04.2021	Refactoring and alignment to Datatype Variant Insert documentation