Rockwell Automation 25-COMM-D PowerFlex 525 DeviceNet Adapter - Manual (Page 56)

56 Rockwell Automation Publication 520COM-UM002A-EN-E - April 2013
Chapter 6 Using Explicit Messaging
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.
Explicit Messaging Process
For information on the maximum number of Explicit Messages that can be
executed at a time, see the documentation for the bridge or scanner and/or
controller that is being used.
CompactLogix Examples
For supported classes, instances, and attributes, see Appendix C , DeviceNet
Objects .
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 or bridge module (download).
➋ The scanner or bridge 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
Esc Sel
1 (Front) 1 (Front) 1 (Front)
2 (Rear) 00:00:BC:2E:69:F6
Complete Explicit
Message
Retrieve Explicit
Message Response
Set up and send Explicit
Message Request
Network Network
TIP To display the Message Configuration screen in RSLogix 5000/Logix Designer,
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.
IMPORTANT The explicit messaging examples in this section can be performed using any
software version of RSLogix 5000/Logix Designer.
The read and write messaging examples in this section are for parameters
which use Class Code 0x93.
The Message Configuration has a Service Type of “Parameter Read” which is
Class code 0x0F, Parameter Object.