Mitsubishi MELSEC LJ71C24, Руководство пользователя

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1 SERIAL COMMUNICATION MODULE FUNCTIONALITY
(3) Nonprocedural protocol
Fixed or variable length messages can be received in accordance with the
external device specifications.
Nonprocedural protocol enables communication between an external device and
the CPU module by freely setting the data format and transmission control
procedures.
It is used for the data communication using the protocols of external devices,
such as measuring instruments, barcode readers, etc.
Any data
Send
Receive
Any data
(4) Bidirectional protocol
The bidirectional protocol enables communication between an external device
and the CPU module using the data format and communication control
procedures for the bidirectional protocol.
Use this protocol to check if the communication is successfully completed.
The data communication is performed as follows.
ENQ
Data
length
When receiving data
Any data
Sum
check
code
ACK
When normal
NAK
Error
code
When abnormal
1) External device sends data to the C24
2) The C24 notifies whether the data
communication has been completed
normally by a response message.