Data Communication And I/O Processing; Data Communication; I/O Processing And Response Delay - Mitsubishi Electric MELSEC iQ-R-R00CPU User Manual

1.3

Data Communication and I/O Processing

Data communication

In data communication, data such as I/O signals, buffer memory, and link device of the CPU module and intelligent function
module are communicated.
There are two modes for data communication: refresh mode which automatically sends\receives the module data into the
device or label of the CPU module at END processing and direct mode which accesses when an instruction is executed in a
program.
When data communication is conducted for the module where a major error occurs, the following operation is performed:
• When access by the contact instruction is executed for the controlled module, non-running, rather than an error, is returned.
When direct access by other instructions is executed, "Major error in module" (error code: 2450) occurs.
• No error occurs when direct access for the non-controlled module is executed.

I/O processing and response delay

The CPU module performs the I/O processing in the refresh mode. Using the direct access input/output in a program,
however, allows the CPU module to perform I/O processing in the direct mode at the time of each instruction execution. This
section describes these I/O processing modes of the CPU module and response delays.
Refresh mode
The CPU module performs I/O processing collectively at a specified timing. The following table lists the refresh timing which
can be specified. ( Page 48 Refresh mode)
Refresh timing
When END processing is performed
At the execution time of specified
program
*1 There are modules which performs the refresh processing at a specified END processing rather than at every END processing. (
User's manual for the module used)
Direct mode
The CPU module performs I/O processing when each instruction is executed in a program. To access input/output modules in
the direct mode, use the direct access input or direct access output in a program. ( Page 50 Direct mode)
Differences between refresh mode and direct mode
The direct mode directly accesses I/O modules at execution of an instruction. Therefore, data is input faster than when it is
input in refresh mode. Processing time required for each instruction, however, takes longer. The following table lists the
availability of the refresh mode and the direct mode for each input and output.
Item
Input/output modules
Input/output of intelligent function modules
Remote input/output in CC-Link IE Controller Network, CC-Link IE Field Network,
CC-Link IE Field Network Basic, MELSECNET/H, or CC-Link
Description
The refresh processing is performed in every END processing
The refresh processing is performed before and after specified program execution. ( Page 65 Group setting for
refresh)
*1
.
Refresh mode
Enabled
1 RUNNING A PROGRAM
1.3 Data Communication and I/O Processing
Direct mode
Enabled
Disabled
47
1