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Computing the Cycle Time Section 10-4
Parallel Processing with Asynchronous Memory Access (CJ1-H CPU Units Only)
Program Execution Cycle The program execution cycle time depends on the following conditions.
• Type and number of instructions in the user program (in all cyclic tasks
that are executed during a cycle, and within interrupt tasks for which the
execution conditions have been satisfied).
• Type and number of Basic I/O Units
• Type and number of Special I/O Units, CJ-series CPU Bus Units, and type
of services being executed.
• Specific servicing for the following Units
• Data link refreshing and the number of data link words for Controller
Link and SYSMAC LINK Units
• Remote I/O for DeviceNet (Master) Units and the number of remote
I/O words
• Use of protocol macros and the largest communications message
• Socket services for specific control bits for Ethernet Units and the num-
ber of send/receive words
• Fixed cycle time setting in the PLC Setup
• File access in file memory, and the amount of data transferred to/from file
memory
• Fixed peripheral servicing time in the PLC Setup
The program execution cycle time is the total time required for the PLC to per-
form the five operations shown in the following tables.
Cycle time = (1) + (2) + (3) + (4) + (5)
Peripheral Servicing Cycle
Time
The peripheral servicing execution cycle time depends on the following condi-
tions.
• Type and number of Special I/O Units, CJ-series CPU Bus Units, and type
of services being executed.
• Type and frequency of event servicing requiring communications ports.
• Use of peripheral and RS-232C ports
Details Processing time and
fluctuation cause
(1) Overseeing I/O bus check, etc.
• CJ1H-CPU
@@H-R:
0.28 ms
• CJ1@-CPU
@@H/CJ1G-
CPU
@@P: 0.3 ms
(2) Program execution Same as for Normal Mode. Same as for Normal Mode.
(3) Cycle time calcula-
tion
Waits for the specified
cycle time.
Same as for Normal Mode.
(4) I/O refreshing Same as for Normal Pro-
cessing Mode.
Same as for Normal Pro-
cessing Mode.
(5) Partial peripheral
servicing
Servicing file access Same as for Normal Pro-
cessing Mode.
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