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I/O Response Time in Tag Data Links Section 10-3
The maximum number of tag data link words that can be transferred by one
EtherNet/IP Unit or CJ2H built-in port is 184,832 words. However, if the num-
ber of tag data link words exceeds the number of words that can be
exchanged with the CPU Unit at one time, the data will be divided and trans-
ferred in multiple data exchanges. The following table shows the number of
words that each CPU Unit can exchange at one time.
The number of data exchanges may double as given in the following table
according to the relation with the CPU Unit’s cycle time and the data process-
ing time of the EtherNet/IP Unit or CJ2H built-in port.
Note (1) With CS/CJ-series PLCs, consecutive data area words specified in the
tag set will be transferred together if possible. Up to 19 send data blocks
can be processed in one data transmission; up to 20 receive data blocks
can be processed in one data transmission. If there are more blocks, the
data will be divided and transferred in separate data transmissions.
(2) The preceding data processing time approximation is the standard formu-
la when a higher priority processing event does not occur in peripheral
servicing. For example, if an instruction such as SEND, RECV, or FAL is
executed, the instruction’s processing will have higher priority, so the data
processing time may be longer.
10-3-3 Effect on the CPU Unit’s Cycle Time
The CPU Unit’s cycle time is affected when the EtherNet/IP Unit or CJ2H built-
in port refreshes tag data and status data with the CPU Unit. This effect
depends on the size of the tag data links, and can be approximated with the
values in the following table. When there are multiple EtherNet/IP Units or
CJ2H built-in ports, the effect is cumulative.
CPU Unit Number of words per data transmission
CS/CJ Series Output/Send: About 7,405 words max. (If there are more words,
the data will be divided.)
Input/Receive: About 7,405 words max. (If there are more words,
the data will be divided.)
Note The total amount of send data and receive data that can be
exchanged at one time is about 14,810 words maximum.
SYSMAC CJ2
Series
Output/send: About 6,432 words max. (If there are more words, the
data will be separated into multiple transmissions.)
Input/receive: About 6,432 words max. (If there are more words,
the data will be separated into multiple transmissions.)
Note The total amount of send data and receive data that can be
transferred at one time is about 12,864 words maximum.
Condition Number of data transmissions
CPU Unit’s cycle time
> EtherNet/IP Unit or CJ2H built-in port
data processing time
Number of data transmissions
based on the data size
CPU Unit’s cycle time
≤ EtherNet/IP Unit or CJ2H built-in port
data processing time
Number of data transmissions × 2
based on the data size