Mitsubishi MELSEC LJ71C24, User Manual

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8 DATA COMMUNICATION USING THE MC PROTOCOL
8.1 Data Communication
8.1.1 Formats and applications of the data communication frames
The MC protocol uses the following communication frames for data communication.
The external device must communicate data in the data format appropriate to the MC
protocol.
Available communication frame
Code of communication
data
Reference
QnA compatible 3C frame Formats 1 to 4 ASCII code
QnA compatible 4C frame Format 5 Binary code
QnA compatible 2C frame
A compatible 1C frame
Formats 1 to 4 ASCII code
MELSEC-Q/L MELSEC
Communication Protocol
Reference Manual
(1) QnA compatible 3C and QnA compatible 4C frames
These frames are mainly used to access all devices and files of the Q/L/QnACPU
from the external device.
It is also possible to access ACPU devices.
(2) QnA compatible 2C frame
This frame can access the device memory of LCPU station (host station) on
which the L series C24 is connected and Q/L/QnACPU stations linked by
multidrop connection.
(3) A compatible 1C frame
This frame has the same message structure as when accessing the
programmable controller CPU using an A series computer link module.
POINT
The message format and control procedure are the same as when accessing the
programmable controller using the conventional modules listed below.
• A series computer link module
• QnA series serial communication module
• Q series C24
The external device side can access the L series C24 with a program used for
accessing the programmable controller via a conventional module.
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