Installing the OpenOPC utility

The OpenOPC application allows Ardexa to read data from Windows machines that are running OPC-DA, via a TCP port, that is; not using Windows DCOM. OPC-DA uses the in-secure Windows DCOM utility to authenticate over an Ethernet network.

As per this Ardexa article (, we DO NOT recommend modern plants use OPC-DA, and we advise strongly against their use, and advise strongly that they be replaced with a more secure solution as soon as possible.

The following instructions provided guidance on how to install the OpenOPC utility to read data from OPC-DA servers. The following software installations must be done on the same Windows machine that is hosting the OPC DA server.


Download the OpenOPC installer from this site: The documentation for the OpenOPC utility can be accessed from this site:


Double click the executable icon for the OpenOPC installer. During installation, make sure the following options are selected or deselected:

Select Next to proceed

Agree to the Licence to proceed

Make sure Command line client and OPC Gateway service are only selected. Un-tick everything else. This is important otherwise you will get errors during the install.

Select the default directory for installation. Once this is done, select Finish to finalize the installation.


Once the install is complete, make the following changes to the OpenOPC Gateway Service. The service administration app can be accessed (from most Windows versions) as Control Panel -> System and Security -> Administrative Tools -> Services.

Open the Services admin app and check that the “OpenOPC Gateway Service” is marked as “started”. Double click on the service name and open the “Recovery” tab. Make sure all the Recovery options are changed to “Restart the Service”, change “Reset fail count after” to 7 days and Change “Restart Service After” to 5 minutes. See the figure below. Make sure "OK" is selected to save these changes.

NOTE The COM driver MUST be run by a single user. If you see errors like "Server already started" or "Server failed", this means that if there are multiple tools trying to access the COM driver via an OPC driver (e.g. OpenOPC and some SCADA tool), then the COM driver MUST NOT be configure to run as "Launching User". Instead, it should run as a "Specific user" and the OpenOPC Service and the SCADA tool should also run as this same user.

  • Open Component Services

  • Computers -> My Computer -> DCOM Config -> AUTOMATIONWORX OPC-Server 3.0

  • Right click -> properties

  • Identity tab

  • Select "this user", user: ardexa, password: ardexa

  • click OK

Firewall Configuration

OpenOPC offers a service, whereby other machines can access data via TCP Port 7766. If the Windows machine is running a firewall, it will need to be configured to allow inbound connections. The firewall service administration app can be accessed (from most Windows versions) as Control Panel -> Windows Firewall -> Advanced Settings. Then undertake the following tasks:

Select "Inbound Rules" from the left had tab, and right click to set up a "New Rule...".

Select "Port", to allow a specific TCP Port

Select TCP and the Specific port of 7766

Select "Allow the Connection"

Select all 3 options

Name the rule as "openopc", and select "Finish"

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