Siemens Simatic S5-101U - Conversion Functions; Shift Operations

5.2.2 Conversion functions
One's complement
The value in accumulator
1
is converted. The result
can be processed in the
accumulator.
Example
The contents of data word
DW 64 are to be inverted
bit by bit and stored in
data word DW 78.
STL
I Explanation
The contents of data word L DW 42
DW 42 are to be interpreted
as a
fixed-pqint number and
stored in data word
DW 35
with inverted sign.
Load data word
DW 64 into
accumulator
1.
Form the one's complement
of the contents of accumula-
tor
1. The result is in
accumulator
1.
Transfer the contents of ac-
cumulator
1 into data word
DW 78.
5.2.3 Shift operations
Load data word DW 42 into
accumulator
1.
Form the two's complement of
the contents of accumulator
1.
The result is in accumulator 1.
Transfer the contents of ac-
cumulator
1 into data word DW 35.
Cperation I Description
I The parameter of this
j statement specifies the
number of bit positions
by which the contents
of accumulator 1 are
shifted to the left
(SLW) or to the right
(SRW). Any bit positions
that become free when
shifting are padded
with zeros.
SLW
0 to 15
SRW
0 to 15
Shift left
Shift right
Example
The last four bits of the
hexadecimal number
14AFH
in data word DW 1 are to
be truncated and the new
hexadecimal number
D14AH
resulting stored in .data
word DW 3.
Note
:
Shift operations are unconditional operations. The last bit shifted out can be
examined by means of a jump operation. A jump can be made with
JZ if the bit is
"0" and with JN or JP if the bit is "1".
STL
L DW 1
SR W 4
T DW 3
Explanation
Load data word
1 into accu-
mulator
1.
Shift the contents of ac-
cumulator
1 four bit posi-
tions to the right.
The bit positions that become
free when shifting are padded
with zeros.
Transfer the contents of ac-
cumulator
1 to data word DW 3.