Rockwell Automation 20-750-DNET PowerFlex DeviceNet Option Module - Manual (Page 67)

Rockwell Automation Publication 750COM-UM002B-EN-P - October 2012 67
Using Explicit Messaging Chapter 6
Performing Explicit
Messaging There are five basic events in the Explicit Messaging process. The details of each
step will vary depending on the type of controller being used. See the
documentation for your controller.
Figure 12 - Explicit Message Process
For information on the maximum number of Explicit Messages that can be
executed at a time, see the documentation for the scanner and/or controller that
is being used.
IMPORTANT There must be a request message and a response message for all Explicit
Messages, whether you are reading or writing data.
Event Description
➊ You format the required data and set up the ladder logic program to send an Explicit Message request to the
scanner module (download).
➋ The scanner module transmits the Explicit Message Request to the slave device over the network.
➌ The slave device transmits the Explicit Message Response back to the scanner. The data is stored in the
scanner buffer.
➍ The controller retrieves the Explicit Message Response from the scanner’s buffer (upload).
➎ The Explicit Message is complete.
➎
➊
➋ ➌
➍
Complete Explicit
Message
Retrieve Explicit
Message Response
Set up and send Explicit
Message Request
Network Network