Rockwell Automation FactoryTalk View Machine Edition Users Guide - Manual (Page 141)

9 • Set up alarms
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connection (1) to the Remote Ack connection, and the alarm at Location 2 is
acknowledged.
How the Remote Ack Handshake connection works
This connection is used to notify the data source that the remote acknowledgement has
been detected by FactoryTalk View.
When the application starts, the Remote Ack Handshake connection has a value of 1.
When the Remote Ack connection value changes, the Remote Ack Handshake
connection’s value toggles from 1 to 0. The next time the Remote Ack value changes, the
Remote Ack Handshake value toggles from 0 to 1.
The Remote Ack Handshake value toggles whether or not the new Remote Ack value
matches a trigger value.
Ensure alarm messages are read by the data source before
sending new messages
This section explains how the Message, Message Notification, and Message Handshake
connections work.
To ensure an alarm message is read by the data source before FactoryTalk View sends a
new message, use message handshaking. While message handshaking is in effect for an
alarm message, FactoryTalk View cannot send a new message to the alarm trigger’s
Message connection.
Methods of alarm message handshaking
Alarm handshaking works by setting the alarm trigger’s Message Notification connection
to 1. As long as the Message Notification connection is set to 1, new messages cannot be
sent to the Messages connection. How the Message Notification connection is reset to 0
depends on how you set up alarm message handshaking.
There are two ways you can use alarm message handshaking:
 To hold the message at the data source for a specific period of time.
 To hold the message at the data source until the data source notifies FactoryTalk View
that the message has been read.
Choose the method that best suits your application needs and communication system.