Rockwell Automation FactoryTalk Historian SE 3.0 H2H Interface User Guide - Manual (Page 94)

UniInt Failover Configuration
88
Detailed Explanation of Synchronization through a Shared File
(Phase 2)
In a shared file failover configuration, there is no direct failover control information passed
between the data source and the interface. This failover scheme uses five Historian tags to
control failover operation, and all failover communication between primary and backup
interfaces passes through a shared data file.
Once the interface is configured and running, the ability to read or write to the Historian tags
is not required for the proper operation of failover. This solution does not require a
connection to the Historian Server after initial startup because the control point data are set
and monitored in the shared file. However, the Historian tag values are sent to the Historian
Server so that you can monitor them with standard Rockwell Automation client tools.
You can force manual failover by changing the ActiveID on the data source to the backup
failover ID.
Business Network
Process Network
IF-Node1
PI-Interface.exe
/host=PrimaryPI
/UFO_ID=1
/UFO_OTHERID=2
/UFO_TYPE=HOT
/UFO_SYNC=\\FileSvr\UFO\Intf_PS_1.dat
IF-Node2
PI-Interface.exe
/host=SecondaryPI
/UFO_ID=2
/UFO_OTHERID=1
/UFO_TYPE=HOT
/UFO_SYNC=\\FileSvr\UFO\Intf_PS_1.dat
DataSource
DCS/PLC/Data Server
Client
Process Book
DataLink
PrimaryPI
PI Server
Role = 1
SecondaryPI
PI Server
Role = 2
Data register 0
.
.
.
Data register n
FileSvr
.\UFO\Intf_PS_1.dat
The figure above shows a typical network setup in the normal or steady state. The solid
magenta lines show the data path from the interface nodes to the shared file used for failover
synchronization. The shared file can be located anywhere in the network as long as both
interface nodes can read, write, and create the necessary file on the shared file machine.
Rockwell Automation strongly recommends that you put the file on a dedicated file server
that has no other role in the collection of data.
The major difference between synchronizing the interfaces through the data source (Phase 1)
and synchronizing the interfaces through the shared file (Phase 2) is where the control data is
located. When synchronizing through the data source, the control data is acquired directly
from the data source. We assume that if the primary interface cannot read the failover control