Advanced OPC Tunnelling

What is OPC Tunnelling?

OPC Tunnelling is a method of networking data between an OPC Server and an OPC Client, without using the problematic DCOM protocol offered by Microsoft.

The problem with DCOM

DCOM is a Microsoft networking protocol used by OPC servers and clients to communicate over a network. It was not designed for use in modern industrial control applications and so has a number of issues, most notably:

• DCOM is difficult to configure, even for the experienced user and getting DCOM to work between different networks can sometimes be impossible.
• Sometimes integrators try to get around these problems by defining very broad access permissions on all computers. However, in an industrial setting, you typically don't want the server and client computers to have the same login permissions, which means using DCOM can actually compromise your network security standards.
• When a DCOM connection is broken, there are very long timeout delays before each side is notified of the problem. In a production environment, these long delays without warning can be a very real problem.
• Recently, DCOM networking has been show to have serious security flaws that make it vulnerable to hackers and viruses. This is particularly worrying to companies who network data across Internet connections or other links outside the company.

Why use the OPC DataHub for tunnel connections?

The OPC DataHub provides a secure SSL network connection that completely avoids all of the problems associated with DCOM.

• The OPC DataHub gives you a secure SSL connection to tunnel your data across a network.
• The OPC Tunnel is very easy to configure and does not require you to change Windows permissions on any of your computers.
• The DataHub implements its own heartbeat and timeout to give you immediate response and automatic recovery from network interruptions.
• You can connect over the Internet or outside the company firewall with complete confidence using secure SSL networking.
• You can network data between OPC DataHubs running on many different platforms, including Windows NT, 2000, XP, 2003 and Vista.
• And the OPC DataHub offers the option to password protect the OPC Tunnel connections for added security.

What is OPC Advanced Tunnelling?

The OPC DataHub also adds the following advanced features:

• The ability to network OPC data from Windows to Linux and QNX applications.
• A powerful built-in scripting language lets you fully customize your OPC applications by attaching custom code to process events and point changes.
• Full read and write support for Excel for accurate reporting and real-time Excel analysis of your plant data.
• The OPC DataHub also has the ability to aggregate data from multiple OPC Servers into a common data set, giving you a single point of access to all of your plant data.
• Support for the latest Web 2.0 technologies lets you build powerful web applications for process visualization and control.
• Full read and write access to ODBC databases so you can log data to SQL/Access/Oracle, or integrate database information into your OPC applications.