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Support

iOPCPlayer for macOS · OPC UA client & NodeSet editor · Mac App Store

Need a hand with iOPCPlayer? You're in the right place. The fastest way to reach me is by email, and most common questions are answered below.

Contact

Email support, direct to the developer: lucasappsupport@gmail.com. I read and answer every message personally. Please include your macOS version, the app version (iOPCPlayer ▸ About iOPCPlayer), and a short description of what you were doing. I typically reply within a few business days.

Prefer a public, searchable thread? You can also open a ticket on GitLab Issues. Please don't post passwords, private endpoints, or certificates there.

Getting started

iOPCPlayer works fully offline and ships with a built-in demo: no account, server, or credentials needed.

Launch iOPCPlayer.
In the sidebar, under Tools, choose Simulation Server.
Click Try Demo Now: this loads a sample model with live, animated values and starts the embedded OPC UA server.
Click Connect Client to this Server, then Connect in the connection dialog that opens.
Browse the address space, read attributes, and create subscriptions to watch values update in real time.

To connect to your own server instead, use Connection ▸ Connect… and enter your endpoint URL (for example opc.tcp://host:4840).

Frequently asked questions

Can I use iOPCPlayer to control a machine or plant?

No. iOPCPlayer is not for safety-critical control and is not certified or approved for industrial use (for example to IEC 61508 or IEC 62443). It is a tool for testing OPC UA connections, exploring servers and running benchmarks. Do not use it to operate, control or safeguard machines, plants or processes where a failure could harm people, damage equipment or stop production. When you connect to a live plant, use a profile with Read only (live plant): writing, method calls, alarm acknowledgement and node management are then blocked.

How do I reopen the main window after closing it?

Use Window ▸ Show Main Window (⌘0), or click the app's icon in the Dock.

The app says the OPC UA client is unavailable.

This means the bundled open62541 library did not load. As the in-app notice says: reinstall iOPCPlayer from the Mac App Store, then restart the app. If it persists, email me with your macOS version and the app version.

I can't connect to my server.

Check the endpoint URL and that the server is reachable from your Mac (firewall, network).
For secure endpoints (Sign / Sign & Encrypt), you'll be asked to trust the server's certificate on first connect.
Error 0x80120000 (BadCertificateInvalid) on a secure endpoint means the server does not trust the app's certificate yet. The app creates its client certificate automatically: mark it as trusted on the server, then connect again.
If macOS asked whether iOPCPlayer may access your local network and you declined, allow it under System Settings ▸ Privacy & Security ▸ Local Network.
For a quick local test, use the built-in Simulation Server (see Getting started above).

How do I make text larger?

iOPCPlayer follows the macOS accessibility settings: open System Settings ▸ Accessibility ▸ Display to adjust text and display options system-wide. All app windows are also freely resizable, so you can give any view more room.

Where is my data stored? Is anything collected?

Nothing is collected. All data stays on your Mac. See the Privacy Policy for details.

How do I import or edit an OPC UA model?

Use File ▸ Open NodeSet… to import a NodeSet2 XML, or open the Professional Editor (⌥⌘E) to create and edit models, then export back to XML or generate C++.

What happens when the connection drops?

iOPCPlayer reconnects on its own, waiting a little longer after each failed attempt (up to 30 seconds). If the server still holds your session, the app simply continues it; otherwise it opens a new session and re-creates every subscription, monitored item and the event monitor with the same settings, so the Data Monitor continues. A banner and the sidebar show “Reconnecting…” with the next attempt; click Retry Now (also in the sidebar's context menu and as Connection ▸ Retry Now, ⌥⌘R) to try at once instead of waiting.

A manual reconnect (Connection ▸ Reconnect, ⌥⌘R) keeps your subscriptions too. Only Disconnect (⇧⌘K) drops them, and it asks first. A connection opened from a read-only profile stays read-only after every reconnect. If the server rejects the login or the certificate, the automatic reconnect stops, because retrying would not help: fix the cause, then choose Retry Now. If a server stays silent, a keepalive notices it within seconds and forces a fresh connection. Use Connection ▸ Performance Test… ▸ Long-run monitor to record drops, availability and latency over hours.

Can I connect to several servers at once?

Yes. Choose Add Server… in the sidebar or Connection ▸ Add Server Connection… (⌥⌘K). Every server appears in the sidebar with its own traffic light; a click shows it in the window while the others keep running. Connection ▸ Multi-Server Stress Test… puts load on several servers at the same time. Only test servers you are allowed to load.

How do I save and restore my monitored items (workspaces)?

iOPCPlayer keeps a workspace for every server automatically: its subscriptions, monitored items with their sampling and filter settings, the event monitor and logged nodes. They are saved on your Mac when they change, when you disconnect and when you quit. The next time you connect to that server, a banner offers to restore them. To restore without asking, turn on Restore a server's last workspace automatically under Settings ▸ Connection ▸ Workspace; Restore the last session at launch offers the servers that were open when you quit.

To keep a setup with several servers, choose File ▸ Save Workspace…. It writes an .iopcworkspace file with all connections, subscriptions and items, but never passwords. Open it with File ▸ Open Workspace… or a double-click in Finder: servers you are already connected to get the items added, servers without security and login connect directly, and all others open the connection dialog as usual. File ▸ Monitored Items imports and exports plain item lists as CSV or JSON. Window ▸ All Servers Monitor (⌥⇧⌘A) shows the monitored items of every connection in one table with a shared trend.

My server is behind a firewall that only allows outgoing connections. Can I still connect?

Yes, with reverse connect. In the connection dialog, switch from Connect to Server to Wait for Server (Reverse). iOPCPlayer then listens on a port of your Mac (4844 by default), and the server opens the connection: configure the server to connect to opc.tcp://<your Mac>:4844. Enter the server's ApplicationUri under Expected Server URI so that only this server is accepted. For Sign or Sign & Encrypt, the server certificate must already be trusted (Connection ▸ Certificates…). macOS may ask whether iOPCPlayer may accept incoming connections; allow it, and make sure no firewall between the server and your Mac blocks the port.

How do I make sure I don't change anything on a live plant?

Turn on Read only (live plant) in the connection dialog. The setting is saved with the server's profile and applied before connecting. It blocks writing values, method calls, alarm acknowledgements, adding or deleting nodes and history updates; reading, browsing, subscriptions and history reads keep working. Read-only connections show a lock in the sidebar. Connection ▸ Read-Only Mode switches it for the connection you are looking at; turning it off asks first.

How do I find the servers on my network?

In the connection dialog, click Find Servers…. Enter the address of a discovery server (a Local Discovery Server, or the server itself) and choose Find Servers, or Find on Network (LDS-ME) for a discovery server with the multicast extension. Browse with Bonjour lists servers that announce themselves on your local network. Choose Use to take over a server's address. Only servers that register with a discovery server or announce themselves via Bonjour appear; for all others, enter the URL directly.

Discovery and connections on your local network need the macOS Local Network permission. If macOS asked and you declined, allow iOPCPlayer under System Settings ▸ Privacy & Security ▸ Local Network.

The server certificate is expired or not yet valid. Can I trust it anyway?

No. Secure connections never accept a certificate outside its validity period, and iOPCPlayer offers no override. If the certificate has expired, ask the server's operator to renew it. If it is not yet valid, or expired although it should not be, the clock of the server or of your Mac is probably wrong: check date, time and time zone on both. The app's own client certificate can be checked, exported and renewed under Connection ▸ Certificates…; after renewing it, mark the new certificate as trusted on the server again.

If a server you trusted before presents a different certificate, iOPCPlayer shows a warning with the old and the new SHA-256 fingerprint. Cancel is the default, and replacing the trusted certificate needs a second confirmation. Compare the fingerprint with the operator before you replace it.

How do I read averages or minimum and maximum values from the server's history?

Open the History tab for the node (or choose Read Server History… in the browser's context menu) and switch the mode to Aggregated. Pick an aggregate, such as Average, Minimum, Maximum, Interpolative, Time Average, Total, Count or Delta, and an interval; Automatic aims at about 300 values for the chosen range. The server computes the values (HistoryReadProcessed), so the result depends on what it supports. If it does not compute an aggregate, iOPCPlayer tells you; try another one or read the raw values. The built-in simulation server keeps raw history only. Results can be shown as a chart, continued with Load More and exported as CSV or JSON.

How do I keep the Data Monitor visible while browsing?

Choose View ▸ Show Data Monitor Panel (⌥⌘5). The panel sits to the right of the browser or above it (switch with the layout button in the panel), or can be popped out into its own window. Drag nodes from the browser into it; dropping an object adds all of its data points.

Structure values from my server show as raw bytes.

iOPCPlayer reads the server's type definitions automatically. If a value still shows as raw bytes, open Window ▸ Data Points, switch to Server Types and choose Identify Server Types; servers that publish neither a DataTypeDefinition nor a type dictionary cannot be decoded.

Reporting a bug

Email lucasappsupport@gmail.com or open a GitLab issue with: the steps to reproduce, what you expected, what happened, your macOS version, and the app version.

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