Mitsubishi Melsec-L Series User Manual page 93

(In ASCII code communication)
Existence in Format 2
E
N
Q
H L H L H L H
- -
Header information (13/15 characters)
(3) Restrictions
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(b) When setting the CH2 side to MC protocol
When data communication is performed using the MC protocol, only the
C24 having the station number designated in the message performs the
process designated by the command.
Furthermore, when data communication is performed using QnA
compatible 2C/3C/4C frames of the MC protocol, the header information for
linked operation is added to messages directed to other stations linked by
multidrop connection.
1) Processing performed by the C24 connected to an external device
• The header information is added to the command messages received
from the external device that are directed to other stations and sends
them to the stations through the other interface.
• The header information is deleted from the response messages
received from other stations and sends them to the external device
using the other interface.
(The header information is also sent during m:n connection.)
2) Operation of the accessed station
The accessed station processes the request contained in the command
message, adds the header information to a response message, and
sends it using the interface that received the command message.
REMARKS
The following describes the header information that is added by the C24 to a
message in linked operation.
1) 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 start of each message
(13 characters for Formats 1, 3 and 4; 15 characters for Format 2).
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 start of each message.
"STX" in Format 3
E
N
Q
L H L H L H L H L
Do not use the above settings for the following cases, because linked operation
cannot be performed.
1) When using the LJ71C24-R2.
2) When an external device is not connected to either of the interfaces.
3) When using the predefined or bidirectional protocol.
4) When communicating data using the modem function.
(In binary code communication)
D S
L T
E X
L H L H
Header information (10 byte)
7 SETTINGS FOR THE C24
D S
L T
E X
L H
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