Shift And Rotate; Shr (Shift Right) And Shl (Shift Left) Instructions - Siemens S7-1200 System Manual

7.10

Shift and rotate

7.10.1

SHR (Shift right) and SHL (Shift left) instructions

Table 7- 143 SHR and SHL instructions
LAD / FBD SCL
out := SHR(
in:=_variant_in_,
n:=_uint_in);
out := SHL(
in:=_variant_in_,
n:=_uint_in);
For LAD and FBD: Click the "???" and select the data types from the drop-down menu.
1
Table 7- 144 Data types for the parameters
Parameter Data type
IN Byte, Word, DWord
N UInt
OUT Byte, Word, DWord
● For N=0, no shift occurs. The IN value is assigned to OUT.
● Zeros are shifted into the bit positions emptied by the shift operation.
● If the number of positions to shift (N) exceeds the number of bits in the target value (8 for
● ENO is always TRUE for the shift operations.
Table 7- 145 SHL example for Word data
Shift the bits of a Word to the left by inserting zeroes from the right (N = 1)
IN 1110 0010 1010 1101
S7-1200 Programmable controller
System Manual, 03/2014, A5E02486680-AG
Byte, 16 for Word, 32 for DWord), then all original bit values will be shifted out and
replaced with zeros (zero is assigned to OUT).
OUT value before first shift:
After first shift left:
After second shift left:
After third shift left:
Description
Use the shift instructions (SHL and SHR) to shift the bit pattern of
parameter IN. The result is assigned to parameter OUT.
Parameter N specifies the number of bit positions shifted:
SHR: Shift bit pattern right
•
SHL: Shift bit pattern left
•
Description
Bit pattern to shift
Number of bit positions to shift
Bit pattern after shift operation
Basic instructions
7.10 Shift and rotate
1110 0010 1010 1101
1100 0101 0101 1010
1000 1010 1011 0100
0001 0101 0110 1000
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