Cycle Time Calculation Example - Omron CJ - 08-2008 Operation Manual

Computing the Cycle Time

10-4-4 Cycle Time Calculation Example

Example 1: Application Based on Basic Instructions and Basic I/O Units
Conditions
Item
CPU Unit
CJ-series CPU Rack
User program
Peripheral port connection
Fixed cycle time processing
RS-232C 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 (Fixed cycle time not set)
(4) I/O refreshing
(5) Peripheral servicing
Cycle time
Example 2: Application Containing Calculations and Special I/O Units
Conditions
Item
CPU Unit
CJ-series CPU Rack
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.
CJ1H-CPU6@H-R
CJ1W-ID261 64-point Input Units
CJ1W-OD261 64-point Output Units
20 Ksteps
Yes and no
No
No
No
Calculation
---
0.016 µs × 10,000 + 0.14 µs/
3 steps × 10,000
0.0039 ms × 2 + 0.0039 ms × 2
(Peripheral port connected only) 0.1 ms
(1) + (2) + (3) + (4) + (5)
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.
CJ1H-CPU6@H-R
CJ1W-ID261 64-point Input Units
CJ1W-OD261 64-point Output Units
CJ1W-AD081 Analog Input Unit
CJ1W-NC413 Position Control Unit
Details
2 Units
2 Units
LD instructions: 10 Ksteps
MOV instructions: 10 Ksteps
Note
• LD: Each instruction is 1 step.
• MOV: Each instruction is 3 steps.
Processing time
With Programming
Device
0.13 ms
0.63 ms
0 ms
0.0164 ms
0.8764 ms
Details
2 Units
2 Units
2 Units
2 Units
Section 10-4
Without Programming
Device
0.13 ms
0.63 ms
0 ms
0.0164 ms
0 ms
0.7764 ms
467