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SWAP |
  
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SWAP |
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Block that performs a swap between the odd bytes and consecutive even bytes into Value and sends the value to Result.
Ladder Representation
Block Structure
Variable Type |
Name |
Data Type |
Description |
VAR_INPUT |
EN |
BOOL |
Block enabling |
Value |
WORD DWORD |
Input variable to be swapped |
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VAR_OUTPUT |
ENO |
BOOL |
End of operation |
Result |
WORD UINT INT DWORD UDINT DINT REAL(*) |
Output value |
Operation
When this block has a TRUE value in EN, it changes the values of the odd bytes (1, 3, 5 and 7) and the consecutive even bytes (2, 4, 6 and 8, respectively) of the Value variable, storing the result in Result.
When EN has FALSE value, Result remains unchanged.
The ENO value forwards to the next Ladder block the EN value after the operation is completed.
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NOTA! Caution when using in Result a variable of REAL type, because the block does not perform type conversion, that is, it only reverses the bytes in memory. |
Block Flowchart
Example in Ladder
The example changes the position of byte 1 value of VALUE (0x44) with byte 2 of VALUE (0x3D), storing the final result (0x44_3D) in RESULT. The block ends with success and ENO output is activated.
The example changes the position of byte 1 value of VALUE (0x96) with byte 2 of VALUE (0xA8) and byte 3 of VALUE (0x0D) with byte 4 of VALUE (0x00), storing the final result (0x0D_00_96_A8) in RESULT. The block ends with success and ENO output is activated.
Example in ST
The example below displays the instructions for applying the example above in the ST language.
VAR VALUE : DWORD := 16#3d44; RESULT : DINT; END_VAR
RESULT := FB_SWAP(EN:=DI1, Value:=VALUE, ENO=>DO1);
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