Description
You can use the "Shift left" instruction to shift the content of the operand at the input IN bit-by-bit to the left and query the result at the OUT output. The input N is used to specify the number of bit positions by which the specified value should be moved.
If the value at the input N is "0", the value at input IN is copied unchanged to the operand at output OUT.
If the value at the input N is greater than the number of available bit positions, the operand value at input IN is shifted to the left by the available number of bit positions.
The bit positions in the right part of the operand freed by shifting are filled with zeros.
The following figure shows how the content of an operand of the WORD data type is shifted by six bit positions to the left:
Parameters
The following table shows the parameters of the instruction "Shift left":
|
Parameters |
Declaration |
Data type |
Memory area |
Description |
||
|---|---|---|---|---|---|---|
|
S7-1200 |
S7-1500 |
S7-1200 |
S7-1500 |
|||
|
EN |
Input |
BOOL |
BOOL |
I, Q, M, D, L or constant |
I, Q, M, D, L, T, C or constant |
Enable input |
|
ENO |
Output |
BOOL |
BOOL |
I, Q, M, D, L |
I, Q, M, D, L |
Enable output |
|
IN |
Input |
Bit strings, integers |
Bit strings, integers |
I, Q, M, D, L or constant |
I, Q, M, D, L or constant |
Value to be shifted. |
|
N |
Input |
USINT, UINT, UDINT |
USINT, UINT, UDINT, ULINT |
I, Q, M, D, L or constant |
I, Q, M, D, L or constant |
Number of bit positions by which the value is shifted. |
|
OUT |
Output |
Bit strings, integers |
Bit strings, integers |
I, Q, M, D, L |
I, Q, M, D, L |
Result of the instruction |
You can select the data type of the instruction from the "???" drop-down list of the instruction box.
For additional information on valid data types, refer to "See also".
Example
The following example shows how the instruction works:
The following table shows how the instruction works using concrete operand values:
|
Parameters |
Operand |
Value |
|---|---|---|
|
IN |
TagIn_Value |
0011 1111 1010 1111 |
|
N |
Tag_Number |
4 |
|
OUT |
TagOut_Value |
1111 1010 1111 0000 |
If the "TagIn" operand has signal state "1", the instruction is executed. The content of the operand "TagIn_Value" is shifted four bit positions to the left. The result is output at the "TagOut_Value" output. If the instruction is executed without errors, the ENO enable output has the signal state "1" and the "TagOut" output is set.