Rockwell Automation 1771-IJ_IK IK ENCODER/COUNTER MODULES - Manual (Page 56)

7–2 Special Programming
Publication 1771ĆUM006B-EN-P - June 2002
Figure 7.1
Ladder Logic for Extending the Count Beyond 999 (PLC-2 Program)
0113
125
0577
168
-
0077
043
GET GET
COUNT
IJ/IK
CURRENT
COUNT
SCAN
PREVIOUS
DIFF.
COUNT
NEW/OLD
0072
400
0077
043
0076
00
<
CONSTANT DIFF.
COUNT
NEW/OLD
ZERO
THROUGH
PASSED
SUBTRACT PREVIOUS COUNT FROM CURRENT COUNT. STORE IN 0077.
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).
0076
00
0077
16
Ctu
0052
Pre 999
ZERO NEGATIVE
VALUE
DIFF.
DIGITS
SIGNIF
MOST
AFTER PASSING THROUGH 0: IF THE SIGN OF THE DIFFERENCE IS NEGATIVE
THEN INCREMENT THE COUNT, IF POSITIVE THEN DECREMENT THE COUNT.
THROUGH
PASSED
Acc 002
0076
00
0077
16
Ctd
0052
Pre 999
ZERO POSITIVE
VALUE
DIFF.
DIGITS
SIGNIF
MOST
THROUGH
PASSED
Acc 002
0052
002
0113
125
Put
0577
168
DIGITS COUNT
IJ/IK
CURRENT
COUNT
SCAN
PREVIOUS
SIGNIF
MOST
DISPLAY THE TOTAL COUNT AND MOVE THE CURRENT COUNT TO THE PREVIOUS COUNT
1
2
3
4
5
GET
GET GET