Rockwell Automation 1771-IJ_IK IK ENCODER/COUNTER MODULES - Manual (Page 40)

5–10 Single Transfer Programming
Publication 1771ĆUM006B-EN-P - June 2002
Figure 5.6
Scan Counter Ć PLCĆ2 Processors
030
CTU
PR003
AC000
030
CTU
PR003
AC000
Branch End
Instruction
15957
The output instruction of both rungs in Figure 5.6 is an up-counter
(CTU) instruction. The first rung, since it is unconditional, is always
true. The second rung, since a branch end instruction by itself is
always false, sets the conditions for the counter as false. Because an
up-counter (CTU) increments for each false to true transition, CTU
030 registers one count each time the program scan occurs.
Scan Counter Ć PLC Processor
Figure 5.7 shows an example scan counter that can be used for a
PLC processor. Because the I/O and program scans of this processor
are asynchronous, this scan counter differs in form and operation
from the scan counter for PLC-2 processors.
Figure 5.7
Scan Counter Ć PLC Processor
200
CTU
PR006
AC000
3
Rung
1
2
11111
11111
L
20017
20017
/
No.
15958
/