Allen-Bradley 2100-ENET, Руководство пользователя

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48 Rockwell Automation Publication 2100-UM006A-EN-P - July 2013
Chapter 6 Using Explicit Messaging
Performing Explicit
Messages There are five basic events in the Explicit Messaging process. The details of each
step varies depending on the type of controller being used. Refer to the
documentation for your controller.
Figure 10: Explicit Message Process
Explicit Message Descriptions
• You format the required data and configure the ladder logic program to
send an Explicit Message request to the scanner or bridge module
(download).
• The scanner or bridge module transmits the Explicit Message Request to
the slave device over the network.
• The slave device transmits the Explicit Message Response back to the
scanner. The data is stored in the scanner buffer.
• The controller retrieves the Explicit Message Response from the scanner’s
buffer (upload).
• The Explicit Message is complete.
For information on the maximum number of Explicit Messages that can be
executed at a time, refer to the user manual for the scanner or bridge and/or
controller that is being used.
ControlLogix Examples
For supported classes, instances, and attributes, refer to the appropriate end
device user manual.
IMPORTANT
There must be a request message and a response message for all Explicit
Messages, whether you are reading or writing data.
Ethernet
Switch
Configure and send Explicit
Message Request
Complete Explicit
Message
Retrieve Explicit
Message Response
TIP
To display the Message Configuration dialog box in RSLogix 5000 software, add a
message instruction (MSG), create a new tag for the message (Properties: Base tag
type, MESSAGE data type, controller scope), and click the
button in the
message instruction.