Omron CJ1W-C113 - REV 02-2008, Operation Manual

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Reading Data with IORD Section 5-5
5-5-6 Precautions when Using IORD
IORD is an instruction which transfers all specified data with a single execu-
tion. Therefore, it increases the cycle time for the ladder program by the time
required to transfer the data.
Refer to Appendix A Performance Characteristics for details on the times
required for transferring positioning sequences. Use them as reference values
for setting cycle time monitoring time.
When using IORD, be sure to transfer data in complete units, and do not start
or end transfer in the middle of data. For example, with X axis sequence #0,
the data unit consists of three words (addresses: 1000 to 1002). If the transfer
is started or ended part-way through, an IORD format error (error code 8700)
will be generated.
Using IORD, a maximum of 128 words of data in consecutive addresses can
be transferred at one time.
5-5-7 IORD Program Example
In this example, speeds #0 and #1 written in 5-4 Writing Data with IOWR are
read. The conditions to be set are the same as those used in the example of
writing the data. The beginning word for the DM Area where the read data is
to be stored is set at D00500.
Note Depending on the timing of IORD instructions, transfer errors may not be
reflected in the CPU Unit. (For details, refer to
5-1 Transferring and Saving
Data. )
CPU Unit
Unit number
Data transfer
PCU (NC413: unit number 2)
Data area
Speed #0
Speed #1