Introduction
Welcome to this presentation on OPC Connection Best Practice. My name is Randy and I am the presenter today. Today’s presentation will take about 45 minutes, including questions and answers. If you have a comment or a question, please use the chat interface at the bottom right-hand side of your desktop. The organizers will pass me your questions and I will include them in the webinar as we move along. If I don’t get your question during the slide presentation itself, I will answer it at the end. I will also send an email responding to each individual question.
Overview
Today’s presentation covers OPC Connections Best Practice. We’re going to talk about the problem definition, the proposed solution, and I will show you OPC Expert Viewer — specifically how to go through connections, collect data, store the data, and perform analysis on it. We’ll also look at troubleshooting messages, which is really the key feature of OPC Expert: helping you troubleshoot and diagnose connection problems.
At the end, I’ll show you how to get a copy of this webinar recording and where you can get a link to download the software.
The Problem: OPC Connectivity
OPC connectivity is very common. When you have a PLC, an OPC server, and an OPC client from any manufacturer or vendor, lots of OPC applications are available. But the connectivity itself is often very problematic, especially that very first connection. So when you have a problem, how exactly do you start to troubleshoot it?
What we need is a way to troubleshoot the connection between your server and your HDMI, historian, or analytical application. That’s where OPC Expert comes in. Specifically: data goes from your PLC into an OPC server, and OPC Expert lets you troubleshoot that connection. If OPC Expert can get through to the OPC server, your application will be able to as well.
What We’ll Cover Today
We will connect to local OPC servers — both UA and DA — and troubleshoot a connection to a remote OPC server. We’ll even collect data and put it into a historian so you can analyze your process data.
Key Features of OPC Expert
Windows Support
OPC Expert supports all Windows versions from Windows XP through Windows 11, and Windows Server from 2003 through 2022 and beyond. Whatever Windows operating system you’re using, it’s supported.
Non-Windows Operating Systems
For those asking about Linux or other non-Windows operating systems, you can get OPC data on those systems as well. OPC Expert helps with that using REST API and web services. We have a separate webinar on that topic.
OPC Protocol Support
OPC Expert supports OPC UA, OPC UA HA, and OPC UA A&C. For OPC Classic, it supports OPC DA, OPC HDA, and OPC Alarms and Events. There are also additional connections including MQTT, Modbus, and REST API.
Communication Profiles
All OPC UA communication profiles are supported. You can connect to local and remote OPC servers using DCOM, TCP/IP, HTTP, or HTTPS. OPC Expert tests those connections and provides accurate, verbose diagnostics.
Architecture
Everything I’m about to show you is included within OPC Expert. Inside OPC Expert you have an OPC DA and OPC UA client feeding into an intelligent engine. Also included are an OPC Alarms and Events client, OPC HDA, and UA HA.
From the intelligent engine, data can be sent to an OPC DA or UA server — allowing you to convert, for example, from OPC DA to UA, or UA to DA, or OPC ANC to HDA. You can also send data to Excel via Microsoft’s Real Time Data engine (RTD), to MQTT with a publisher/subscriber/broker setup, to databases such as Microsoft SQL, MySQL, or Access, or out via REST API and web services. A client API toolkit is also included for building your own OPC clients and servers.
In this webinar, since we’re focused on diagnosing connection problems, we’re concentrating specifically on the client connections — how a local connection is made, how a remote connection is made, and how to store that data.
Demo: Connecting to Local OPC Servers
OPC Expert is a single executable — there’s no installation, no Windows Registry changes. When you double-click it, OPC Expert extracts all the files it needs right in place. When you’re done, you can simply delete it. This makes it suitable for audited systems where you need to put something on and take it right back off.
When you browse the local computer, you’ll see a list of OPC DA servers, Alarms and Events servers, and HDA servers. Some servers have multiple entries — for example, one for DA and one for alarms and events. Using the Properties view on any server, you can see the Prague ID, description, port, process ID, and the server executable — information that’s sometimes difficult to find on its own.
To subscribe to data, you can drag and drop tags or double-click them. The interface shows value, timestamp, quality, data type, and number of updates received. A green checkmark indicates everything is working. You can connect to multiple OPC DA servers and OPC UA servers in the same session — OPC Expert treats them identically.
Demo: Connecting to a Remote OPC Server
To connect to a remote computer, right-click Entire Network and add a computer by name. An automated browse will attempt to find computers, but on most networks this fails. In that case, simply enter the computer name manually.
Firewall Error
When the browse fails, OPC Expert shows a detailed error message. In this case, it told me the cause was likely a firewall blocking the connection, and the suggested action was to deactivate the firewall on the remote computer. Once the firewall was turned off and I re-browsed, the OPC servers appeared immediately.
Authentication Error
After connecting, an exclamation mark appeared on the data items. The error message explained that while we were able to connect to the OPC server, we were not receiving asynchronous callbacks — meaning no data updates. This is usually caused by authentication problems. OPC Expert told me exactly how to fix it: go to Computer Management, then Local Users and Groups, and ensure the OPC server’s user account exists on this machine.
To find the OPC server’s user account, I right-clicked the server in OPC Expert and went to Properties. This showed me the process name (Simulate2) and the user account it was running under (Sam). I confirmed this in Task Manager on the remote computer. I then created a local account named Sam and set the password. Once that was done, OPC Expert immediately recognized that things were working and the items changed to green checkmarks.
Testing UA Connections
For OPC UA connections, you can use the Connect Custom option to test different connection mechanisms — anonymous, username/password, or certificate-based. You can try different security modes and see immediately which ones succeed or fail and why. Once you identify a working connection profile, you connect and subscribe to data just as you would with OPC DA.
Demo: Archiving and Historian
With data coming in from both local and remote servers, select all subscribed tags with Ctrl+A and create a new archive. Storage options include Microsoft SQL Server, SQLite, MySQL, Amazon, a network share, or a CSV file. OPC Expert has data management built in. Once configured, OPC Expert creates a historian that begins storing data immediately — you can see the status shown as Live.
Running as a Windows Service
By default, OPC Expert is not running as a service. To continue collecting data after closing the application, go to Tools and select Install as a Windows Service. You can run it as a local system account or a specific account. Once installed, OPC Expert Archive Server appears in Windows Services and runs with minimal CPU overhead. You can then close the OPC Expert interface and the archive server continues running in the background.
When you reopen OPC Expert, it automatically reconnects to the running service and resumes displaying collected data. You can then right-click any tag, select Read History, specify a time range, and retrieve the stored data points. The trend viewer — also included in OPC Expert — uses the REST API internally, which means you can view trend data from a phone or any browser.
Demo: Alarms and Conditions
OPC Expert also supports OPC UA Alarms and Conditions and OPC Classic Alarms and Events. After connecting to an OPC UA server that provides alarm simulation, right-click and select OPC UA Alarms and Conditions to either monitor alarms in real time or archive them to a CSV, SQL, or other destination. The live alarm view shows severity, state changes, and condition updates as they arrive. OPC Expert also includes a web view so you can monitor alarms from a phone.
Summary
What we covered today: connecting to local OPC servers, troubleshooting remote OPC DA connections including firewall and authentication issues, testing OPC UA connection profiles, collecting and archiving data to a historian, running OPC Expert as a Windows service, reading historical data, and monitoring OPC alarms and conditions.
Remember: if your application can’t connect, OPC Expert most likely won’t be able to connect either. And when OPC Expert can connect, it gives you verbose information about any errors and helps you troubleshoot exactly what’s going on.
Getting OPC Expert and Additional Resources
OPC Expert and OPC Rescue are both free to download. The OPC servers demonstrated today — including the Kepware server and the simulation server — also have free demo versions available on our website. With OPC Expert you can also thread, bridge, and tunnel connections, and we have separate videos showing how to do all of that.
If you want to learn more about OPC and how these connections work, you can attend one of our Hands-On Workshops and earn your Certified OPC Professional designation. Workshops are available publicly and privately, on-site or remote, with a live instructor. You can find upcoming dates at opc.com.
We will email you this webinar recording along with a link to download OPC Expert, links to viewer examples, and an invitation to our next webinar. If you have questions, you can reach us by email at info@opcti.com or by phone. You can also explore OPC Expert directly at expert.com/viewer.
