12 CPU Unit Cycle Time
12-12
CJ2 CPU Unit Software User’s Manual
z 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 instruc-
tions, data movement instructions, and floating-point calculation instructions. Here, a CJ2H-CPU6@-
EIP CPU Unit is used.
Conditions
Calculation Example
Item Details
CPU Unit CJ2H-CPU6@-EIP
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 Posi-
tion Control Unit
2 Units
User program 20 Ksteps LD instructions: 12 Ksteps
MOV instructions: 6 Ksteps
+F instructions: 2K steps
(LD: Each instruction is 1 step.
MOV: Each instruction is 3 steps.
+F: Each instruction is 4 steps)
Peripheral USB port connection Yes and no
Fixed cycle time processing No
Serial port connection No
Peripheral servicing with other
devices (Special I/O Units, CPU
Bus Units, and file access)
No
Process name Calculation
Processing time
Programming Device
connected to built-in
USB port
Programming Device
not connected to built-
in USB port
(1) Overseeing --- 0.20 ms 0.20 ms
(2) Program execution 0.016 ms × 12,000 + 0.14 µs/
3 steps × 6,000 + 0.24 µs/
4 steps × 2,000
0.59 ms 0.59 ms
(3) Cycle time calculation
for minimum cycle time
(Fixed cycle time not set) 0 ms 0 ms
(4) I/O refreshing 0.0041 ms × 2 + 0.0041 ms × 2
+ 0.05 ms × 2 + 0.17 ms × 2
0.4564 ms 0.4564 ms
(5) Peripheral servicing (Peripheral USB port connec-
tion only)
0.1 ms 0 ms
Cycle time (1) + (2) + (3) + (4) + (5) 1.35 ms 1.25 ms
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