Omron NJ Series

Appendices
A-14
NJ-series CPU Unit Software User’s Manual (W501)
Guidelines are provided below for calculating the various processing times.
Use the following formula for the I/O refresh processing time.
I/O refresh processing time = I/O refresh overhead time
+ (Larger of the EtherCAT slave processing time and the CJ-series Unit
processing time)
The following describes how to determine the I/O refresh overhead time, EtherCAT slave processing
time, and CJ-series Unit processing time used in the above formula.
 I/O Refresh Overhead Time
The I/O refresh overhead time is given by the following table, depending on whether there are Ether-
CAT slaves and CJ-series Units.
 EtherCAT Slave Processing Time
Use the following formula for the EtherCAT slave processing time.
 (I/O refresh time for each EtherCAT slave  Number of slaves) - 70 [s]
In the above formula,  represents the total processing time for all EtherCAT slaves.
If the result that is calculated from the above formula is a negative number, the EtherCAT slave pro-
cessing time is regarded as 0 s.
The method for calculating the I/O refresh time for each EtherCAT slave is provided later.
Common
processing
time
System com-
mon pro-
cessing 1
• Variable refresh processing (if there
are accessing tasks) is performed.
• Motion input processing
• Data trace processing
Performed. Performed. Performed.
System com-
mon pro-
cessing 2
• Variable refresh processing (if there
are refreshing tasks) is performed.
• Variable access processing external to
the Controller to ensure concurrency
with task execution
Performed. Performed. Performed.
System over-
head time
Other system common processing Performed. Performed. Performed.
I/O Refresh Processing Time
EtherCAT slaves CJ-series Units I/O refresh overhead time [s]
Present –60
None Present 30
Processing Processing contents
Primary
periodic
task
Priority-16
periodic
task
Priority-17
and prior-
ity-18 peri-
odic tasks