6-9
6 I/O Memory Areas
CJ2 CPU Unit Software User’s Manual
6-2 I/O Area
6
6-2-1 Input Bits
When the immediate refreshing variation of an instruction is specified by inputting an exclamation
point just before the instruction and the instruction’s operand is an input bit or word, refreshing is
performed as described below. This immediate refreshing is performed in addition to the normal I/O
refreshing performed once each cycle.
z Bit Operands
Just before the instruction is executed, the ON/OFF status of the 16 I/O points allocated to the word
containing the specified bit will be read to the PLC.
z Word Operands
Just before the instruction is executed, the ON/OFF status of the 16 I/O points allocated to the spec-
ified word will be read to the PLC.
z Example
In the following example, CIO 1.01 is allocated to switch 1, an external switch connected to the input
terminal of an Input Unit. The ON/OFF status of switch 1 is read and reflected in CIO 1.01 just
before !LD 1.01 is executed.
When the IORF(097) (I/O REFRESH) instruction is executed, the input bits in the specified range of
words are refreshed. This I/O refreshing is performed in addition to the normal I/O refreshing per-
formed once each cycle.
The following IORF(097) instruction refreshes the status of all I/O points in I/O Area words CIO 0 to
CIO 3. The status of input points is read from the Input Units and the status of output bits is written
to the Output Units.
Immediate Refreshing
IORF(097) Refreshing
1.01
!LD 1.01
CIO 1.01
↑
CPU UnitInput Unit
Read
just
before
in-
struc-
tion
execu-
tion.
Switch 7
Switch 1
Switch 0
Ladder symbol Mnemonic
0
3
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