Rockwell Automation 20-COMM-I Interbus Adapter - Manual (Page 64)

6-2 Using Explicit Messaging (PCP Communications)
There are five basic events in the Explicit Messaging process defined
below. The details of each step will vary depending on the controller.
Refer to the documentation for your controller.
Important: There must be a request message and a response message
for all Explicit Messages, whether you are reading or
writing data.
Figure 6.1 Explicit Message Process
Event
1. Format the required data and set up the ladder logic program to send
an Explicit Message request to the scanner module (download).
2. The scanner module transmits the Explicit Message Request to the
slave device over the Interbus network.
3. The slave device transmits the Explicit Message Response back to
the master.
4. The controller retrieves the Explicit Message Response.
5. The Explicit Message is complete.
Running Explicit Messages
➊
➍
➎
Retrieve Parameter
Message Response
Complete Parameter
Message
PWR STS
PORT MOD NET A NET B
➋
➌
Set up and send
Parameter Message
20COMM-UM007A-EN-P.book Page 2 Tuesday, January 22, 2002 10:52 AM