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Computing the Cycle Time Section 10-4
10-4-4 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 CJ1H-
CPU6@H-R CPU Unit is used.
Conditions
Calculation Example
Example 2: Application Containing Calculations and Special I/O Units
The following example shows the method used to calculate the cycle time
when Basic I/O Units and Special I/O Units are connected in the PLC and the
program consists of 20K steps of basic instructions, data movement instruc-
tions, and floating-point calculation instructions. Here, a CJ1H-CPU6@H-R
CPU Unit is used.
Conditions
Item Details
CPU Unit CJ1H-CPU6@H-R
CJ-series CPU Rack CJ1W-ID261 64-point Input Units 2 Units
CJ1W-OD261 64-point Output Units 2 Units
User program 20 Ksteps LD instructions: 10 Ksteps
MOV instructions: 10 Ksteps
Note
• LD: Each instruction is 1 step.
• MOV: Each instruction is 3 steps.
Peripheral port connection Yes and no
Fixed cycle time processing No
RS-232C port connection No
Peripheral servicing with other
devices (Special I/O Units, CPU
Bus Units, and file access)
No
Process name Calculation Processing time
With Programming
Device
Without Programming
Device
(1) Overseeing --- 0.13 ms 0.13 ms
(2) Program execution 0.016 µs × 10,000 + 0.14 µs/
3 steps × 10,000
0.63 ms 0.63 ms
(3) Cycle time calculation (Fixed cycle time not set) 0 ms 0 ms
(4) I/O refreshing 0.0039 ms × 2 + 0.0039 ms × 2 0.0164 ms 0.0164 ms
(5) Peripheral servicing (Peripheral port connected only) 0.1 ms 0 ms
Cycle time (1) + (2) + (3) + (4) + (5) 0.8764 ms 0.7764 ms
Item Details
CPU Unit CJ1H-CPU6@H-R
CJ-series CPU Rack CJ1W-ID261 64-point Input Units 2 Units
CJ1W-OD261 64-point Output Units 2 Units
CJ1W-AD081 Analog Input Unit 2 Units
CJ1W-NC413 Position Control Unit 2 Units
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