Bit Field Distribute with Target (BTDT)

This information applies to the CompactLogix 5370, ControlLogix 5570, Compact GuardLogix 5370, GuardLogix 5570, Compact GuardLogix 5380, CompactLogix 5380, CompactLogix 5480, ControlLogix 5580, and GuardLogix 5580 controllers. Controller differences are noted where applicable.

The BTDT instruction first copies the Target to the Destination. Then the instruction copies the specified bits from the Source, shifts the bits to the appropriate position, and writes the bits into the Destination. The Target and Source remain unchanged.

Available Languages

Ladder Diagram

This instruction is not available in a ladder diagram.

Function Block

Structured Text

BTDT(BTDT_tag);

Operands

Function Block

Operand	Type	Format	Description
BTDT tag	FBD_BIT_FIELD_DISTRIBUTE	structure	BTDT structure

Structured Text

Input Parameter	Data Type	Description
EnableIn	BOOL	If cleared, the instruction does not execute and outputs are not updated. If set, the instruction executes. Default is set.
Source	DINT	Input value containing the bits to move to Destination. Valid = any integer
SourceBit	DINT	The bit position in Source (lowest bit number from where to start the move). Valid = 0-31
Length	DINT	Number of bits to move. Valid = 1-32
DestBit	DINT	The bit position in Dest (lowest bit number to start copying bits into). Valid = 0-31
Target	DINT	Input value to move to Dest prior to moving bits from the Source. Valid = any integer

Output Parameter	Data Type	Description
EnableOut	BOOL	Indicates if instruction is enabled.
Dest	DINT	Result of the bit move operation.

See Structured Text Syntax
for information on the syntax of expressions within structured text.

Description

When true, the BTDT instruction first copies the Target to the Destination, and copies a group of bits from the Source to the Destination. The group of bits is identified by the Source bit (lowest bit number of the group) and the Length (number of bits to copy). The Destination bit identifies the lowest bit number bit to start with in the Destination. The Source and Target remains unchanged.

If the length of the bit field extends beyond the Destination, the instruction does not save the extra bits. Any extra bits do not wrap to the next word.

Affects Math Status Flags

Controllers	Affected Math Status Flag
CompactLogix 5380, CompactLogix 5480, ControlLogix 5580, Compact GuardLogix 5380, and GuardLogix 5580 controllers	Yes
CompactLogix 5370, ControlLogix 5570, Compact GuardLogix 5370, and GuardLogix 5570 controllers	No

See Math Status Flags.

Major/Minor Faults

None specific to this instruction. See Common Attributes for operand-related faults.

Execution

Function Block

Condition/State	Action Taken
Prescan	EnableIn and EnableOut bits are cleared to false.
Tag.EnableIn is false	EnableIn and EnableOut bits are cleared to false.
Tag.EnableIn is true	EnableIn and EnableOut bits are set to true. The instruction executes.
Instruction first run	N/A
Instruction first scan	N/A
Postscan	EnableIn and EnableOut bits are cleared to false.

Structured Text

Condition/State	Action Taken
Prescan	See Prescan in the Function Block table.
Normal Execution	See Tag.EnableIn is true in the Function Block table.
Postscan	See Postscan in the Function Block table.