Bit Field Distribute (BTD)

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.
The BTD instruction copies the specified bits from the Source, shifts the bits to the appropriate position, and writes the bits into the Destination.
Available Languages
Ladder Diagram
BTD_LD_avail_v31
Function Block
This instruction is not available in function block.
Structured Text
This instruction is not available in structured text.
Operands
There are data conversion rules for mixed data types within an instruction. See Data Conversion.
Ladder Diagram
Operand
Type
Format
Description
Source
SINT
INT
DINT
immediate
tag
Tag that contains the bits to move
Source bit
DINT
immediate (0-31)
Number of the bit (lowest bit number) from where to start the move
Must be within the valid range for the Source data type
Destination
SINT
INT
DINT
tag
Tag where to move the bits
Destination bit
DINT
immediate (0-31)
The number of the bit to which the data should be moved must be within the valid range for the Destination data type.
Length
DINT
immediate (1-32)
Number of bits to move
Description
When enabled, the BTD instruction 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 Source) and the Length (number of bits to copy). The Destination bit identifies the lowest bit number to start with in the Destination. The Source 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.
A SINT or INT tag is converted to a DINT value by zero-fill.
Affects Math Status Flags
No
Major/Minor Faults
None specific to this instruction. See Common Attributes for operand-related faults.
Execution
Ladder Diagram
Condition/State
Action Taken
Prescan
N/A
Rung-condition-in is false.
N/A
Rung-condition-in is true.
The instruction copies and shifts the Source bits to the Destination.
Postscan
N/A
Examples
Example 1
Ladder Diagram
BTD_LD_ex1_v31
When enabled, the BTD instruction moves bits within value_1.
BTD value_1 before BTD
Example 2
BTD_LD_ex2_v31
When enabled, the BTD instruction moves 10 bits from value_1 to value_2.
BTD Value_1_2 before and after BTD instruction
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