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Rockwell Automation Publication 2100-UM006A-EN-P - July 2013 47
Chapter
6
Using Explicit Messaging
This chapter provides information and examples that explain how to use Explicit
Messaging to configure and monitor the connected device.
About Explicit Messaging Explicit Messaging is used to transfer data that does not require continuous
updates. With Explicit Messaging, you can configure and monitor a slave device’s
parameters on the network.
Topic Page
About Explicit Messaging 47
Performing Explicit Messages 48
ControlLogix Examples 48
ATTENTION: Risk of injury or equipment damage exists. The examples in this
publication are intended solely for purposes of example. There are many
variables and requirements with any application. Rockwell Automation does not
assume responsibility or liability (to include intellectual property liability) for
actual use of the examples shown in this publication.
ATTENTION: Risk of equipment damage exists. If Explicit Messages are
programmed to write parameter data to nonvolatile storage (NVS) frequently,
the NVS quickly exceeds its life cycle and causes the E3 Plus module to
malfunction. Do not create a program that frequently uses Explicit Messages to
write parameter data to NVS.
IMPORTANT
When an explicit message is performed, by default no connection is made
because it is an unconnected message. When timing of the message
transaction is important, you can create a dedicated message connection
between the controller and the end device by checking the Connected box on
the Communications tab message configuration dialog box during message
setup. These message connections are in addition to the I/O connection.
However, the trade off for more message connections is decreased network
performance. If your application cannot tolerate this, do not check the
Connected box, which is recommended.