Kepware - RedundancyMaster

Reliable data collection


Kepware RedundancyMaster

The Kepware RedundancyMaster increases the reliability and availability of your data acquisition by combining different OPC servers into redundant pairs. Each server pair is then sent to the client as one RedundancyMaster server which ensures the correct data flow based on server availability. If for any reason the OPC client loses its communication with its primary OPC, the secondary OPC will take over without any system downtime.

Easy to use

RedundancyMaster is very easy to use. It takes a few minutes to establish a second OPC server as secondary. After that you select which one is the primary and secondary and that’s it. There is no need for changes to the OPC since RedundancyMaster uses a drop-in application. Besides all this RedundancyMaster also has the option to use email-notifications, link and object monitoring and diagnostics logging.

Connection Mode

There are 3 possible modes in which RedundancyMaster can operate. Which mode is selected, defines when the RedundancyMaster activates and switches form the primary to the secondary server. There are 3 different modes for the RedundancyMaster:

Cold (Active machine only)

The RedundancyMaster will only connect to the primary server in this mode, all the client requests will be handled by the primary server. If the primary server fails, the RedundancyMaster will connect with the secondary server. This mode is perfect for people who want to minimise the amount of system resources that are allocated since there will only be one connection to one server at any given time. It also reduces network traffic since there is no need to poll the inactive machine in addition to the active machine, as in other modes.

The drawback to this setting is the amount of time it takes to fail-over to the inactive server. When communication loss is detected with the active server, the application needs to establish the connection to the inactive server, subscribe to all items on behalf of the client, and initiate the appropriate callback mechanisms.


  • Reduced network traffic
  • Minimised amount of resources that are allocated
  • Larger switch-time compared to other modes

Warm (Both machines, items on active machine)

The RedundancyMaster will connect with both the primary server as the secondary server, but only items from the primary server will be active, this means that only the primary server will send data notifications. If the primary server fails, the RedundancyMaster will connect quicker with the secondary server. The benefits are that fail-over time is minimised over "cold" mode operation, since the redundancy application will only have to initialise data callbacks to the inactive server to begin receiving data. If you need to minimise the loss of data in your application, and at the same time want to minimise network traffic, you should use this connection mode.


  • Minimised network traffic
  • Increased amount of resources that are allocated
  • Switch-time is minimized

Hot (Both machines, items on both machines)

The RedundancyMaster is connected with both the primary and the secondary server. Both these servers will send data notifications. If the primary server fails, the secondary server will instantly take over without any switch-time at all. The benefit of this setting is that fail-over time occurs immediately after detecting the loss of the active server. If loss of data is very crucial to your application, you should use this connection mode.


  • Increased network traffic
  • Increased amount of resources that are allocated
  • No switch-time


Manual - RedundancyMaster

A manual from Kepware.


Data Sheet - RedundancyMaster

A data sheet from Kepware.