Message Format And Control Procedure - Mitsubishi Electric MELSEC iQ-F Series FX5 User Manual

Message format and control procedure

This section describes the message format and the control procedures when performing the data communication using the 3E
frame.
Data format
The data format for communicating between the built-in Ethernet port and the external device consists of header and
application data.
■Request message
Header
Subheader
destination
■Response message
Header
Subheader
destination
Header
This header is for TCP/IP and UDP/IP.
Add the header for external equipment to CPU module (command message) at the external equipment side before sending
the message (normally the header is added automatically).
It is not necessary to set the header for CPU module to external equipment (response message) by the user because the
header is added by the CPU automatically.
Application data
Application data is divided into subheader and text.
The subheader indicates whether a message is the command message or the response message. (Refer to  Page 17
Subheader configuration.)
Text is the request data (command) and the response date (response) in each function. (For details on each function, refer to
Page 39 List of Commands and Functions or and after.)
■When communicating data in ASCII code
External equipment
CPU module
3 MESSAGE FORMAT
16
3.1 Message Format
Request Request Request
destination destination
network station No. module I/O
No. No.
Application data
Request Request Request
destination destination
network station No. module I/O
No. No.
Application data
Subheader Text (command)
4 bytes The text differs
depending on
the function.
Application data
Request Request Reserve Command Subcommand Request
destination data
multidrop length
station No.
Request Response End
destination data length code
multidrop
station No.
The text differs depending
whether the command
4 bytes
Subheader
Application data
Response
data
on the function and
ends normally or not.
Text (response)
data