Data Communication Using The Bidirectional Protocol - Mitsubishi Melsec-L Series User Manual

11 DATA COMMUNICATION USING THE BIDIRECTIONAL PROTOCOL

This communication enables data transfer between an external device and a CPU
module using the data format and transmission control procedure for the bidirectional
protocol.
The feature of this data communication is that a response message is sent from the
data receiving side to the data sending side, informing if the communication was
completed.
Use this to check if the data communication was completed normally.
Sequence programs for sending and receiving data are required on the CPU module
side.
When receiving data
Communication programs using the bidirectional protocol can be easily replaced
with those of the predefined protocol by the predefined protocol support function of
GX Works2.
With the predefined protocol, programs can be run only by starting communication
according to the specified protocol, and this can reduce the number of steps
considerably.
For the communication using the predefined protocol, refer to Chapter 9.
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11 DATA COMMUNICATION USING THE BIDIRECTIONAL PROTOCOL
1) External device sends data to the C24
Data
ENQ
length
When normal
When abnormal
2) The C24 notifies whether the data
communication has been completed
normally by a response message.
POINT
Sum
check
Any data
code
ACK
Error
NAK
code
11
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