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7–2
Special Programming
SUBTRACT PREVIOUS COUNT FROM CURRENT COUNT. STORE IN 0077.
CURRENT
PREVIOUS
IJ/IK
SCAN
COUNT
COUNT
0113
0577
1
GET
GET
125
168
IF THE DIFFERENCE IS GREATER THAN A CONSTANT (COUNT PASSED THROUGH
ZERO), THEN INCREMENT THE COUNT. THE CONSTANT MUST BE LESS THAN 1/2 THE
TOTAL COUNTS OF THE IJ/IK (HALF OF 999 OR 4095).
NEW/OLD
COUNT
CONSTANT
DIFF.
0077
0072
2
<
GET
043
400
AFTER PASSING THROUGH 0: IF THE SIGN OF THE DIFFERENCE IS NEGATIVE
THEN INCREMENT THE COUNT, IF POSITIVE THEN DECREMENT THE COUNT.
PASSED
DIFF.
THROUGH
VALUE
ZERO
NEGATIVE
0076
0077
3
00
16
DIFF.
PASSED
VALUE
THROUGH
POSITIVE
ZERO
0077
0076
4
16
00
DISPLAY THE TOTAL COUNT AND MOVE THE CURRENT COUNT TO THE PREVIOUS COUNT
MOST
CURRENT
SIGNIF
IJ/IK
DIGITS
COUNT
0052
0113
5
GET
GET
125
002
Publication 1771 UM006B-EN-P - June 2002
Figure 7.1
Ladder Logic for Extending the Count Beyond 999 (PLC-2 Program)
NEW/OLD
COUNT
DIFF.
0077
-
043
PASSED
THROUGH
ZERO
0076
00
MOST
SIGNIF
DIGITS
0052
Ctu
Pre 999
Acc 002
MOST
SIGNIF
DIGITS
0052
Ctd
Pre 999
Acc 002
PREVIOUS
SCAN
COUNT
0577
Put
168
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