Omron SYSMAC CJ - REFERENCE MANUAL 01-2008 Reference Manual page 1006

Basic I/O Unit Instructions
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 instruc-
tion, it will be affected by the execution results of that instruction.
IORD(222) can be used in an interrupt task, which allows high-speed pro-
cessing of specific I/O data with an interrupt. If IORD(222) is used in an inter-
rupt 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 (A40213) 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) (CJ1-H-R CPU Units only).
• Words allocated to the same Special I/O Unit were read or written by
IORD(222) or IOWR(223).
B
IORD
C
S
D
=
B
A
Section 3-23
967