Cycle Time Calculation Example - Omron CJ2 CPU UNIT SOFTWARE User Manual

12-2-4 Cycle Time Calculation Example

Example 1: Application Based on Basic Instructions and Basic I/O Units
The following example shows the method used to calculate the cycle time when only Basic I/O Units
are connected in the PLC and the program consists of 20K steps of basic and data movement
instructions. Here, a CJ2H-CPU6@-EIP CPU Unit is used.
Conditions
Item
CPU Unit
CJ-series CPU Rack
User program
Peripheral USB port connection
Fixed cycle time processing
Serial port connection
Peripheral servicing with other
devices (Special I/O Units, CPU
Bus Units, and file access)
Calculation Example
Process name
(1) Overseeing
(2) Program execution
(3) Cycle time calculation
for minimum cycle time
(4) I/O refreshing
(5) Peripheral servicing
Cycle time
CJ2 CPU Unit Software User's Manual
CJ2H-CPU6@-EIP
CJ1W-ID261 64-point Input
Units
CJ1W-OD261 64-point Out-
put Units
20 Ksteps
Yes and no
No
No
No
Calculation
---
0.016 µs × 10,000 + 0.14 µs/
3 steps × 10,000
(Fixed cycle time not set)
0.0039 ms × 2 + 0.0039 ms × 2 0.0164 ms
(Peripheral USB port connec-
tion only)
(1) + (2) + (3) + (4) + (5)
12 CPU Unit Cycle Time
Details
2 Units
2 Units
LD instructions: 10 Ksteps
MOV instructions: 10 Ksteps
(LD: Each instruction is 1 step.
MOV: Each instruction is 3 steps.)
Processing time
Programming Programming Device
Device connected to not connected to
peripheral USB port peripheral USB port
0.20 ms 0.20 ms
0.63 ms 0.63 ms
0 ms 0 ms
0.0164 ms
0.1 ms 0 ms
0.95 ms 0.85 ms
12
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