Omron SYSDRIVE 3G3RV, User Manual

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Communications Functions
6-
97
n
Protocol Macro Function
The
protocol macro function makes it possible to customize a communications protocol in order to create a
macro
according to the specifications of the serial communications port of a general-purpose peripheral
device.
The
protocol macro function is mainly used for the following jobs.
• Creation
of the message communications frame
• Creation
of Send & Recv procedures for the message communications frame
Creating a Message
The
message can be created according to the communications specifications of the general-purpose peripheral
device
(Inverter) as a counterpart.
A
DSR message can include variables to set data in the I/O memory (such as data memory) of the CPU Unit or
write
response data to the I/O memory.
Each
component of a message is in the memory of the Communications Board. Therefore, the CPU Unit can
just
execute the PMCR instruction to send or receive the data, with no need to write ladder programs for the
communications
protocol.
Fig 6.62 Creating a Message
Step to Send and Receive Messages
Sending
and receiving messages as a single step includes step-type commands, such as Send, Recv, Send &
Recv,
and Wait commands.
The
step can be finished or switched to another step according to the result of the step.
Fig 6.63 Sending and Receiving Messages
TERMS
This manual uses the terms “message, DSR message, and response” to express the communications data
exchanged.
Message: A DSR message or response.
DSR message: A message sent by the Master for instructions to the Inverter.
Response: A message that the Inverter returns in compliance with a DSR message from the Master.
PMCR Instruction
SYSDRIVE 3G3RV
Send
CPU Unit
DSR message
Reception
Response
Serial Communications Board
PMCR Instruction
SYSDRIVE 3G3RV CPU Unit
Next process
according to
the result.
Step 0
To step n according
to the result
Serial Communications Board