Rockwell Automation 1772-LV Mini-PLC - 2/15 Programmable Controller (Series B) Programming and Operations - Manual (Page 61)

Advanced Instruction Set
Chapter 6
6Ć4
Figure 6.2
Rungs for Measuring Scan Time
031
15
CTU
031
PR 999
031
13
AC 000
Rung 1
CTU
031
PR 999
AC 000
Rung 2
?
031
14
RTO
032
0.1
PR 999
Rung 3
AC 000
: G G
010
032
Store
1 Rung 4
Store
2
Store
3
:
031
14
CTR
031
PR 100
Rung 5
AC 000
031
14
RTR
032
Rung 6
0.1
PR 999
AC 000
Here is an explanation of each rung:
Rung 1: The count increments its accumulated value each time this rung is true.
Rung 2: This rung enables the counter to increment on the next scan. If we did
not have this rung, the counter would always be true and it would not
increment. Remember: Counters increment only on false to true transitions.
Rung 3: The timer times in tenths of seconds when we are counting. This value
is displayed on the industrial terminal screen.
Rung 4: The actual scan time is displayed beneath store 2 and store 3 in
milliseconds.
Rung 5: An input device is controlling the counter.