Rockwell Automation Allen-Bradley DriveLogix 5730, Руководство пользователя

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7-10 Communicating with Devices on an ControlNet Link
MSG instruction to keep the connection open (cache) or to close it after
sending the message.
Connected messages are unscheduled connections on ControlNet.
If a MSG instruction uses a connection, you have the option to leave the
connection open (cache) or close the connection when the message is done
transmitting.
The following is from the 5720 manual and is a place holder. We need to put
real information here!
The controller has the following limits on the number of connections that
you can cache:
This type of message: And this communication method: Uses a connection:
CIP data table read or write X
PLC2, PLC3, PLC5, or SLC (all types) CIP
CIP with Source ID
DH+ X
CIP generic CIP Optional
(1)
block-transfer read or write X
(1)
You can connect CIP generic messages, but for most applications, we recommend you leave CIP generic messages unconnected.
If you: Then:
Cache the connection The connection stays open after the MSG instruction is done. This
optimizes execution time. Opening a connection each time the
message executes increases execution time.
Do not cache the
connection The connection closes after the MSG instruction is done. This frees up
that connection for other uses.
If you have this software
and firmware revision: Then you can cache:
11.x or earlier
•
block transfer messages for up to 16 connections
•
other types of messages for up to 16 connections
12.x or later up to 32 connections