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 (https://app.gitbook.com/@ardexa/s/knowledge/configure/plugins/access-to-opc-da-data), 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

Download the OpenOPC installer from this site: https://sourceforge.net/projects/openopc/files/openopc/1.3.1/OpenOPC-1.3.1.win32-py2.7.exe/download. The documentation for the OpenOPC utility can be accessed from this site: https://github.com/sightmachine/OpenOPC/blob/master/doc/OpenOPC.pdf

Installation

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.

Configuration

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.

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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Outline
Download
Installation
Configuration
Firewall Configuration