Omron CJ1W-EIP21 Operation Manuals page 313

3. I/O Refreshing Time
You must calculate the processing time for I/O refreshing between the EtherNet/IP Unit and the CPU
Unit. (I/O refreshing is when the data is actually transferred.)
The following two elements are relevant.
• Number of Fragments
Even if the data size of the tag data links is equal to or less than the maximum link data size that
can be sent and received for each EtherNet/IP Unit (369,664 bytes), the data transfer between the
CPU Unit and the EtherNet/IP Unit must be fragmented if the data transfer size that can be pro-
cessed by the CPU Unit in one transfer is exceeded. The maximum data transfer sizes are given
below.
Data Transfer Sizes for Each Data Transfer with the CPU Unit
Output/send data: Approx. 14,810 bytes max.
Input/receive data: Approx. 14,810 bytes max.
• I/O Refresh Processing Time
The actual I/O refresh processing time depends on the following conditions.
(Number of nodes × 1 ms) + I/O refresh time* + 1 task period
*1.I/O Refreshing Time Guidelines
I/O refresh processing type
Input refreshing
Output refreshing
4. Actual Time Required for Data Transfer
The actual time that is required for data transfer is calculated as follows based on the values found
for (2) and (3) above.
Task period × (Number of data transfers (2) + Number of fragments (3) − 1) + I/O refresh pro-
cessing time (3)
CJ-series EtherNet/IP Units Operation Manual for NJ-series CPU Unit (W495)
12 Communications Performance and Communications Load
Total link data size
20 bytes
0.3 ms
0.1 ms
1,444 bytes 2,888 bytes
0.5 ms 0.7 ms
0.3 ms 0.6 ms
12,864
8,664 bytes bytes or
more
1.6 ms 2.1 ms
1.2 ms 2.3 ms
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