Mitsubishi Electric MELSEC iQ-R Series User Manual page 401

Precautions
■When setting to nonprocedural protocol
Exclusive control of the received data is necessary when data is communicated using the nonprocedural protocol since all of
the connected stations receive the data.
■When setting to MC protocol
When data communication is performed using the MC protocol, only the C24, of which station number is specified in the
massage, performs the process designated by the command.
Furthermore, when data communication is performed with 2C/3C/4C frame of the MC protocol, the header information for
interlink operation is added to messages directed to other stations linked by multidrop connection.
● Processing performed by C24 connected to a target device
• C24 adds the header information to the command massages directed to other stations, which was received from the target
device, and transmits them to the other stations through the other interface.
• C24 deletes the header information from the response messages received from the other stations, and transmits them to
the target device through the other interface. (The header information is also sent during the multidrop connection using the
interlink operation setting.)
● Operation of the accessed station
• The accessed station processes the request contained in a command message, adds the header information to a response
message, and sends it using the interface that received the command message.
The header information for the interlink operation, which is added by C24 to a message is as shown below.
• When communicating with ASCII code (Formats 1 to 4)
The following 13- or 15-character header information is added immediately before the control code (ENQ/
STX/ACK/NAK) at the head of each message (13 characters for Formats 1, 3 and 4; 15 characters for
Format 2).
• When communicating in binary mode (Format 5)
The following 10-byte header information is added immediately before the control code (DLE + STX) at the
head of each message.
(In ASCII code communication)
Existence in Format 2
E
N
Q
H L H L H L H L H L H L
Header information (13/15 characters)
Do not use the above settings for the following cases because the interlink operation cannot be performed.
• When using RJ71C24-R2.
• When a target device is not connected to either of the interfaces.
• When communicating data using the predefined or bidirectional protocol.
• When communicating data using the modem function.
"STX" in Format 3
(In binary code communication)
E D S
N E T
Q L X
H L H L L H
Header information (10 byte)
D S
E T
L X
L H L H
21 INDEPENDENT/LINKED OPERATION OF INTERFACE
21.2 Setting and Data Flow of Interlink Operation
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