Rockwell Automation FactoryTalk View Machine Edition Users Guide - Manual (Page 143)

9 • Set up alarms
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How messages are queued
FactoryTalk View can queue up to 128 messages while it waits for the Message
Notification connection to be reset to 0. Queued messages are sent to the data source on a
first in, first out basis.
If the alarm message queue fills before the Message Notification connection is reset to 0,
an error message is sent to FactoryTalk Diagnostics.
How the Message connection works
This connection is used to send the message associated with a trigger value to the data
source.
The message is sent only if the alarm message’s Message to Tag option is selected.
If you are going to generate text alarm messages in multiple languages, make sure the tag
assigned to this connection can accommodate the string length of the messages in each
language. For information about using multiple languages, see Chapter 12.
How the Message Notification connection works
This connection is used to notify FactoryTalk View that an alarm message has been sent to
the data source and FactoryTalk View must wait to send another message.
When the application starts, the Message Notification connection is set to 0. When a
message is written to the Message connection, the Message Notification connection value
changes to 1. When the hold time expires, or the Message Handshake connection changes
to a new non-zero value, the Message Notification connection value changes from 1 to 0.
Messages for an alarm trigger are queued if the Message Notification connection is set
to 1.
How the Message Handshake connection works
Use the Message Handshake connection to reset the Message Notification connection
when the data source has read the alarm message.
Set up the data source to send a new non-zero value to the Message Handshake
connection when it has read the message at the Message connection.
Connections that apply to all alarms
These connections apply to all alarms:
 Silence—Assign a tag to this connection to notify the data source that all alarms have
been silenced (for applications that will run on a personal computer only).