Omron CJ - INSTRUCTIONS REFERENCE MANUAL 07-2009 Reference Manual page 844

Function
IORD(222) reads the number of words designated in S+1 from the memory area of the Special I/O Unit
or CPU Bus Unit whose unit number is designated by S and outputs the data to D. Only Special I/O
Units or CPU Bus Units mounted on CPU Racks or Expansion I/O Racks can be designated. Refer to
the operation manual of the Special I/O Unit or CPU Bus Unit from which data is being read for specific
details for each Unit.
S
S+1
Hint
• When IORD(222) is executed, the execution results are reflected in the condition flags. In particular,
the Equals Flag turns ON when reading is completed. Input the condition flags such as the Equals
Flag with output branching from the same input conditions as the IORD(222) instruction.
• If the Special I/O Unit or CPU Bus Unit is busy, the reading operation will not be executed. Use the
Equals Flag to create a self-maintaining program, as shown below, so that IORD(222) will be
executed with each cycle until the reading operation is executed.
B
A
• When the input condition is met, self maintenance is performed by output A and IORD(222) is
executed with each cycle until the Equals Flag turns ON. When the reading is completed and the
Equals Flag turns ON, output B turns ON and the self maintenance is cleared.
• Be sure to place condition flags directly after IORD(222) instructions, and not after any other
instructions. If a condition flag is placed after another instruction, it will be affected by the execution
results of that instruction.
Precaution
• IORD(222) can be used in an interrupt task, which allows high-speed processing of specific I/O data
with an interrupt. If IORD(222) is used in an interrupt task, always disable cyclic refreshing of the
specified Special I/O Unit by turning ON the corresponding Special I/O Unit Cyclic Refreshing
Disable Bit in the PLC Setup.
• When cyclic refreshing of the specified Special I/O Unit is enabled in the PLC Setup (the
corresponding Special I/O Unit Cyclic Refreshing Disable Bit is OFF), a non-fatal Duplicate Refresh
Error will occur and the Interrupt Task Error Flag (A402.13) will go ON in the following cases.
• Words allocated to the same Special I/O Unit were already refreshed by IORF(097) or
FIORF(225).
• Words allocated to the same Special I/O Unit were read or written by IORD(222) or IOWR(223).
CS/CJ/NSJ Series Instructions Reference Manual (W474)
Unit number of Special I/O Unit
or CPU Bus Unit
Desig-
nated
number
of words
read.
IORD
C
S
D
=
B
A
3. Instructions
3
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