Rockwell-automation 20-750-DNET PowerFlex DeviceNet Option Module Instrukcja Użytkownika Pobierz pdf (Strona 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

➋➌

➍

Complete Explicit

Message

Retrieve Explicit

Message Response

Set up and send Explicit

Message Request

Network Network

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Rockwell-automation 20-750-DNET PowerFlex DeviceNet Option Module Instrukcja Użytkownika Strona 67