Mitsubishi Q02CPU User Manual

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3.8 I/O Processing and Response Lag
3
SEQUENCE PROGRAM CONFIGURATION AND
EXECUTION CONDITIONS
3.8 I/O Processing and Response Lag
The CPU module performs I/O processing in a refresh mode.
Using direct access I/O in a sequence program, however, allows the CPU module to
perform direct mode I/O processing corresponding to each instruction.
This section explains these I/O processing modes and response lags of the CPU module.
(a) Refresh mode( Section 3.8.1)
The refresh mode batch-accesses I/O modules before start of sequence program
operation.
(b) Direct access mode( Section 3.8.2)
The direct mode accesses an I/O module when each instruction is executed in a
sequence program.
To access an I/O module in the direct mode, use the direct access input or direct
access output in a sequence program.
(1) Differences between refresh mode and direct access mode
Since the direct access mode makes direct access to an I/O module at execution of
an instruction, it imports input data faster than the refresh mode.
However, its instruction processing time is longer than that of the refresh mode.
The direct access mode is available for the I/O used with the I/O modules and
intelligent function modules mounted on the main base unit and extension base units.
The differences between the refresh mode and the direct access mode are shown in
Table3.7.
* 1: The Basic model QCPU cannot use the I/O of the I/O link mounted on extension base units.
Table3.7 List of differences between refresh mode and direct access mode
Item Refresh mode Direct access mode
I/O module mounted on base unit
Available Available
I/O of intelligent function module mounted on
base unit
I/O of I/O link mounted on extension base
unit
*1
I/O used in CC-Link IE controller network,
MELSECNET/H network system or CC-Link
system
Available N/A

Mitsubishi Q02CPU Specifications

General

Brand	Mitsubishi
Model	Q02CPU
Category	Controller
Language	English