Handling Transparent And Additional Codes For Bidirectional Protocol Data Communication - Mitsubishi Electric MELSEC iQ-R Series User Manual

16.5
Handling Transparent and Additional Codes for
Bidirectional Protocol Data Communication
This section explains how to handle the transparent codes and additional codes during data communication using the
bidirectional protocol.
Adding/deleting additional code designation code
The data designated by the additional code is added to/deleted from the data to be transmitted or received.
Data range of transmit/receive processing
The range of transmitted/received data to which processing to transmit/receive transparent codes and additional codes is
performed includes data length, data portion, and error code of a message.
Head code (ENQ, ACK, NAK) and sum check code of each message are not included.
Ex.
Transmission sequence
Target device
E
Data section
N
Data
(Designated transmission
Q
CPU module
length
data)
L H
C24 performs the following processing during data transmission/reception.
■At the time of request data reception
When an additional code set for reception is detected, C24 removes the additional code data and perform data reception
processing by treating the immediately succeeding 1-byte data as a part f the received data during the reception of a request
data.
■At the time of response message transmission
When transparent code/additional code data set for transmission is detected, C24 transmits data by adding the additional
code designation data immediately before it during the transmission of the response message to data reception.
■At the time of request data transmission
When transparent code/additional code data set for transmission is detected, C24 transmits data by adding the additional
code designation data immediately before it during data transmission.
■At the time of response message reception
When an additional code set for reception is detected, C24 removes the additional code data and perform data reception
processing by treating the immediately succeeding 1-byte data as a part of the received data during the reception of the
response message to data transmission.
Sum
check
code
L H
*

16.5 Handling Transparent and Additional Codes for Bidirectional Protocol Data Communication

*
A N Error
(When (When
C A
code
normal) abnormal)
K K
L H
Applicable data range
*
16 TRANSPARENT CODES AND ADDITIONAL CODES
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