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In today’s process control environment, OPC is becoming the protocol of choice. There are many OPC Servers offered by companies specializing in connectivity and PLC, DCS and equipment manufacturers often offer an OPC server interface as part of their product suite.
The standard has empowered software vendors to create OPC client applications that easily access real-time data from any piece of equipment offered by any vendor.
Data from the factory floor is more available now than ever before. However, accessing this data often means connecting over corporate or insecure public networks.
Networking OPC between computers can be challenging. The networking protocol for OPC is DCOM, which was not designed for industrial real-time data transfer. DCOM can be difficult to configure, responds poorly to network breaks, and has serious security flaws.
Using DCOM between different LANs, such as connecting between manufacturing and corporate LANs, or between different Windows domains is sometimes impossible to configure.
Using OPC over DCOM also requires more network traffic than some networks can handle because of bandwidth limitations or due to the high traffic already on the system.
To overcome these limitations, there are “tunnelling” software packages,an alternative to DCOM, to transfer OPC data over a network. Let’s take a closer look at how tunnelling solves the issues associated with DCOM, and how the OPC DataHub from Cogent Real-Time Systems provides a secure, reliable, and easy-to-use tunnelling solution with many advanced features.
 To Learn more: Download the free Secure OPC Tunneling White Paper or attend the free live webcast on Friday 31 October.
In addition to Tunneling, the OPC DataHub can function as an OPC client, DDE client, DDE Server, OPC Server, Web Server, and more, giving it incredible capabilities that NO OTHER TUNNELING SOLUTION can offer. Learn more about OPC DataHub
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OPC DataHub
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Other tunneling products
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The OPC DataHub keeps all OPC transactions local to the computer, thus fully protecting the client programs from any network irregularities.
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Other products expose OPC transactions to network irregularities, making client programs subject to timeouts, delays, and blocking behavior. Link monitoring can reduce these effects, while the OPC DataHub eliminates them.
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The OPC DataHub mirrors data across the network, so that both sides maintain a complete set of all the data. This shields the clients from network breaks as it lets them continue to work with the last known values from the server. When the connection is re-established, both sides synchronize the data set.
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Other products pass data across the network on a point by point basis and maintain no knowledge of the current state of the points in the system. A network break leaves the client applications stuck with no data to work with.
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A single tunnel can be shared by multiple client applications. This significantly reduces network bandwidth and means the customer can reduce licensing costs as all clients (or servers) on the same computer share a single tunnel connection.
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Other tunnelling products require a separate network connection for each client-server connection. This increases the load on the system, the load on the network and increases licensing costs.
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