Chapter 4 Messages Of Serial Communication Module; Types And Purposes Of Messages; Formats And Codes; Frame - Mitsubishi Electric MELSEC IQ-R series Reference Manual

4
MESSAGES OF SERIAL COMMUNICATION
MODULE
This section explains the specifications of the messages of MC protocol and access range when connecting with serial
communication from an external device.
4.1

Types and Purposes of Messages

The messages of MC protocol can be classified as shown in the following table depending on the supported device and its
intended purpose.

Formats and codes

There are five formats for the message that can be used for serial communication module.
Setting value Format
1 Format 1
2 Format 2
3 Format 3
4 Format 4
5 Format 5
Set the format with the communication protocol setting of Engineering tool.
Communication using binary code shorten the communication time since the amount of communication data
is reduced by approximately half as compared to the one using ASCII code.

Frame

This section explains the types and purposes of the frames (data communication messages) used by the external device to
access the supported devices using MC protocol.
The frames for serial communication modules are as follows:
Frame Features and purposes
4C frame Accessible from external devices with the maximum
access range.
3C frame These message formats are simplified compared to the
4C frame.
Data communication software for MELSEC-QnA series
2C frame
programmable controllers can be used.
1C frame These frames have the same message structures as
when accessing the CPU module using an MELSEC-A
series computer link module.
Data communication software for MELSEC-A series
programmable controllers can be used.
4 MESSAGES OF SERIAL COMMUNICATION MODULE
28
4.1 Types and Purposes of Messages
Code of communication data
ASCII code
ASCII code
ASCII code
ASCII code
Binary code
Remarks

Format with block number appended
Format enclosed with STX and ETX
Format with CR and LF appended at the end
Can be used by 4C frame.
Compatible message format
Dedicated protocols for MELSEC-QnA series serial
communication modules (QnA extension frame).
Dedicated protocols for MELSEC-QnA series serial
communication modules (QnA frame).
Dedicated protocols for MELSEC-QnA series serial
communication modules (QnA simplified frame).
Dedicated protocols for MELSEC-A series computer link
modules
Reference
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Format
Formats 1 to 5
Formats 1 to 4