Applies To:
  • CitectSCADA

Configuring DCOM security to allow OPC clients to access remote OPC servers is sometimes not possible i.e. across domains, through firewalls, across the internet etc. Even in a local environment where DCOM configuration should be possible, it is often prohibitively difficult. However there are alternatives.

Proprietary Solutions:

Products such as MatrikonOPC Tunneller offer another route to bypassing DCOM. In this case, Tunneller is installed on both client and server PCs, interfacing with the true OPC client and server via local COM. The two copies of Tunneller then communicate with one another using one of a number of supported protocols, including HTTP.


The OPC XML-DA specification defines an alternative mechanism for remote OPC communications. XML-DA is based on SOAP, and generally uses HTTP as its transport. As a result XML-DA is likely to work through firewalls, and also offers the possibility of cross-platform OPC.

Various products exist which allow OPC (COM) clients and servers to communicate remotely via an XML-DA bridge/gateway.


Advosol, DCOM bridge.