Rockwell Automation FactoryTalk View Site Edition Users Guide - Manual (Page 373)

14 • S ETTING UP F ACTORY T ALK SYSTEM AVAILABILITY
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Managing HMI data in an online redundant system
To help ensure that HMI data generated in an online redundant system is as accurate and
accessible as possible, keep the following considerations in mind.
Synchronize time clocks on redundant computers
HMI servers manage the synchronization of HMI tag alarm states, between primary and
secondary servers.
For example, if there are five unacknowledged alarms at the primary server when it fails,
the same five alarms will be show at the secondary server, when the failover is complete.
Alarm states are also synchronized when the system switches back to the primary server.
To ensure tight synchronization of alarm states, synchronize clocks on the primary and
secondary HMI server computers to a time server.
If the clocks are not synchronized, when a failover occurs, multiple alarms or inconsistent
information might be shown in HMI tag alarm summaries, on connected clients.
In Alarm Messages
Out of Alarm Messages
Acknowledge Messages
Identification
Out of Alarm Label
Deadband Any change The change takes effect, for any new or existing alarm
transactions associated with the modified tag.
TIP: The AlarmAcceptEdits command will not apply
changes to the contents of User Default messages, for the
InAlarm Messages, Out of Alarm Messages, and
Acknowledge Messages properties.
Acknowledge (bit) Any change The change takes effect, for any new or existing alarm
transactions associated with the modified tag.
If an Acknowledge Bit tag is added with the Auto Reset
property set to True, the Acknowledge Bit tag is set to 0.
Handshake (bit) Any change The change takes effect, for any new or existing alarm
transactions associated with the modified tag.
If a Handshake Bit tag is added, and alarming is started
with handshaking turned on (AlarmOn /H), and if the
alarm tag is in alarm, the Handshake Bit tag is set to 1.
If a Handshake Bit tag is added with the Auto Reset
property set to True, and alarming is started with
handshaking turned on (AlarmOn /H), and if the alarm
tag is not in alarm, the Handshake Bit tag is set to 0.
You can set up a Microsoft Windows domain to include a time-synchronization service. For
details, see Windows Help for setting up the domain.
If this property Is changed to this value This is what happens when AlarmAcceptEdits is run