Automatic failover for redundant networks and devices

Minimize downtime due to failed networks and devices

The Media-Level Redundancy plug-in for TOP Server is included for use with all compatible drivers.  This powerful component allows redundant failover for network, network type and device and is supported for the following drivers (click here for a list of drivers not supported):

  • Serial or Ethernet drivers
  • Modbus Plus drivers operating in client mode
  • The OPC UA Client driver

Simply select the Media-Level Redundancy plug-in as one of the components to install when installing TOP Server - it's included at no additional charge.

In the event of a failure, Media Level Redundancy allows the duplicate device or redundant network to take over without interrupting communication.  This minimizes data loss, maximizing uptime and increasing the availability of your critical industrial data.

Two types of redundancy for greater flexibility

TOP Server supports two types of redundancy, providing users with the flexibility to meet the specific needs of their unique device architecture.

Communications Path Redundancy provides redundant network paths to communicate to a critical device.

Device Pair Redundancy is where you configure two devices as a redundant pair where one is primary and the other is secondary.

These modes of redundancy can either be used together or separately to provide the level of reliability your application requires at all levels of downstream communications from TOP Server.

Communications Path Redundancy minimizes downtime due to network issues

Communications Path Redundancy involves establishing redundant physical connections to the same device, such as having both an Ethernet and serial connection to the same device.

Since it is possible to specify a Network Interface (NIC) card at the channel level, this mode can also be used to enable network redundancy, as well, for Ethernet devices either supporting multiple connections or that have multiple network modules.

This type of redundancy decreases the likelihood of lost communications due to the cabling or communications module in a particular device.



Device Pair Redundancy minimizes downtime due to device issues

Device Pair Redundancy involves having two identical devices running the same logic, allowing fail over in the event that one of the devices becomes disabled.

Device Pair Redundancy decreases the likelihood of downtime caused by an issue with the actual device or controller affecting responsiveness to TOP Server requests.


Specialized system tags allow monitoring of redundant failover conditions from your client

Each redundancy definition has a set of specific read-only system tags created in the _System tag group for the primary device. These tags can be used to observe the current failover status from any client application, including whether the primary or secondary connection is current active and how many failovers have occurred since the last reset of the counter.

For full details, please refer to the Media-Level Redundancy plug-in help file (which also installs with TOP Server).


Even server-level redundancy is possible with Redundancy Master

With critical data it’s important to have redundant systems, when that means having redundant data gathering too. For full redundancy, including OPC DA server redundancy, you can add the Redundancy Master to make this easy and transparent to your OPC DA client applications.

OPC UA Server Redundancy

If you are operating TOP Server as an OPC UA Server and need redundancy, the Cogent DataHub is the solution and supports scenarios from simple to complex.

Learn More About DataHub Redundancy for OPC UA or DA


Important Notes:

  • Media-Level Redundancy includes support for a Switch On Trigger mode, where the switch over for the primary to the secondary can be based on a tag value, quality, or time on inactivity as well as On Failure.
  • The TOP Server also has always supported device and network redundancy through standard system tags which you can use to switch which device your connected to or even which Ethernet Network your connected through. However, it is recommended to take full advantage of the redundancy capabilities available with the Media Level Redundancy plug-in for the best performance.
  • For a list of drivers that do NOT support Media-Level Redundancy, please click here.

Get Started Now

The demo is the full product once licensed. Once a client application connects to the  TOP Server, the TOP Server runtime will operate for 2 hours at a time. At the end of the 2 hour demo period, the demo timer must be reset by restarting the TOP Server runtime service.

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