Rockwell Automation 1775-S5_SR5,D17756.5.5 User Manual PLC-3 FAMILY I/0 User Manual
Page 103
Programming DH and DH+
Message Procedures
Chapter 6
6-12
Since the leftmost bit of an expression is the sign bit, this means that the
right bit shift on a 32-bit value does not change the sign of the numeric
value. The rightmost bits still shift out of the value and are lost as shown
in the following examples:
GRINDER = (GRINDER >> 1)
GRINDER Value:
Bit Pattern (32Ćbits):
Decimal Value:
Before operation
100...00000101
-2147483643
After operation
110...00000010
-1073741822
$H0:1 = ($H0:1 >> 1)
$H0:1 Value:
Bit Pattern (32Ćbits):
Decimal Value:
Before operation
010...00000101
1073741829
After operation
001...00000010
536870914
Comparison Operators
Comparison operators result in a value of 1 if the comparison is true and 0
(zero) if the comparison is false. For example:
$I12:24 = ($CACC:1.GE.$CACC:2)
If the accumulated value of counter 1
is:
Then the scanner stores this value in
input file 12 word 24:
greater than or equal to the accumulated
value of counter 2
1
less than the accumulated value of
counter 2
0