Rockwell Automation FactoryTalk View Machine Edition Users Guide - Manual (Page 142)

F ACTORY T ALK V IEW M ACHINE E DITION U SER ’ S G UIDE
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Hold the message for a specific period of time
To set up an alarm trigger’s alarm message handshaking so that the message at the
Message connection is held for a specific period of time, assign a tag to the Message
Notification connection and specify a hold time in the Advanced tab of the Alarm Setup
editor.
How handshaking works
This method of alarm message handshaking works as follows:
1. When an alarm occurs, the alarm message is sent to the Message connection.
2. The Message Notification connection is set to 1.
As long as the Message Notification connection is set to 1, FactoryTalk View cannot
send new messages to the data source.
3. The hold time timer begins timing.
4. When the hold time has expired, the Message Notification connection is reset to 0 and
FactoryTalk View can send a new message to the Message connection.
Hold the message until the data source acknowledges that it
has read the message
To set up an alarm trigger’s alarm message handshaking so that the message at the
Message connection is held until the data source notifies FactoryTalk View that it has read
the message, use two connections: the Message Notification connection and the Message
Handshake connection.
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.
How handshaking works
If you use the Message Handshake connection, handshaking works like this:
1. When an alarm occurs, the alarm message is sent to the Message connection.
2. The Message Notification connection is set to 1.
As long as the Message Notification connection is set to 1, FactoryTalk View cannot
send new messages to the data source.
3. When the data source has read the message, it sends a new non-zero value to the
Message Handshake connection.
4. The Message Notification connection is reset to 0 and FactoryTalk View can send a
new message to the Message connection.