OPC UA Simulator

The simulator makes your PC behave like one or more OPC UA servers, so an OPC UA client — a SCADA system, a gateway, an MES connector or your own code — can be developed and tested before the real server exists, or after it has gone back to the customer.

• Standards-compliant servers. The OPC UA side is the open-source node-opcua stack, so a client sees a real server: GetEndpoints, FindServers, secure channels, sessions, Browse, Read, Write and subscriptions.
• Any number of servers. Each has its own endpoint opc.tcp://host:port/path, security modes, sign-in rules and identity. Each appears as a tab.
• Security as in the field. None, Sign and SignAndEncrypt endpoints with a self-signed server certificate made on first start; anonymous sessions allowed or refused; user name and password checked against the users you enter.
• An address space from a table. Dotted names become folders and variables under Objects. Boolean to Double, String and DateTime, scalar or array, each with a description, unit, writable or read-only access and a status code.
• Live values. Fixed, random between limits, incrementing, toggling or pulsed booleans, strings cycling through a list, a DateTime following the clock. Changes to the table apply to the running server at once.
• Full visibility. Every service call is logged with the client address, the service, the nodes touched and the result.

1. Start the simulator. On Windows, run tamidas-opcua-simulator.exe: on the first start it unpacks itself into your application-data folder, then opens the web UI in your browser at http://localhost:8083. The window it runs in can stay minimised.
2. Press + Add server, give it a name, keep port 4840 (the OPC UA default) or choose another, and press Save. The server starts and its tab opens with the endpoint it serves.
3. Press Upload CSV / XLS and take the sample file offered in the dialog: a pump house with a pump, a meter, an array, a variable that answers a bad status, and a clock. Fourteen variables appear and their values start moving.
4. Point your client at the endpoint shown on the tab, for example opc.tcp://192.168.1.20:4840/Simulator, browse Objects and read PumpHouse.Pump1.Speed. Every call appears in the request log at the foot of the page.

An OPC UA client finds a server by its endpoint URL, agrees on security, opens a session and then browses, reads, writes or subscribes. The simulator answers every step like a real server does.

Inside the simulator, each server is one node-opcua server instance built from the variable table of its tab. The simulation updates the values on the server's update interval (section 4.5), and a change you make to the table — a new variable, a removed one, a different mode — is applied to the running server without a restart.

A server is one simulated OPC UA server. Every server appears as a tab named after it, with its endpoint, status and sessions above its variable table.

Adding a server

Press + Add server. A panel slides in from the right.

Press Save. The server is created, started, and its tab opens. If it could not start — for example the port is in use — the server is still created and the reason is shown on the tab; fix the setting with Edit and start it again.

Endpoint

Security and sign-in

What the server says about itself

Application name, application URI, product name, manufacturer and software version are what the server reports in GetEndpoints and FindServers and what a client shows in its server list. Fill them in to mimic a particular vendor's server, or leave the defaults.

Start, stop, edit, remove

Stop closes the server's sessions and port; Start brings it back with the same table. Edit opens the panel again; saving restarts the server when the endpoint or security changed. Remove deletes the server and its variables. Servers run independently: one can be stopped while the others answer.

Simulation

Update interval (ms) is how often the random, incrementing and toggling values of this server change, 1000 ms by default. A client that subscribes with a shorter sampling interval sees the same value repeated until the next update.

The variable table of a tab is the server's address space under Objects. Each row is one variable; the dots in its name are the folders above it.

Press + Add variable for a new row, edit cells in place, and press Save changes: the running server takes the new table at once, and a browsing client sees the variable appear or disappear. Download CSV exports the table in the import format.

The Mode column says how a value moves on the server's update interval.

The sample table shows one of each: a random pump speed and temperature, an incrementing energy total, a toggling run feedback, a pulsed alarm, a cycling recipe name and a clock.

A client may write a variable whose Writable column is Yes, with a value of the variable's own data type. The simulator then freezes that variable: it keeps the written value and stops simulating it, so the client reads back exactly what it wrote — the way a setpoint or a command bit behaves on a real server. Edit the row and save to resume simulation.

Every write, accepted or refused, is in the request log with its result.

Press Upload CSV / XLS and drop a .csv, .xls or .xlsx file, or browse for one. Replace current table starts from the file; Append adds its rows to the table.

Mandatory columns: Name (the dotted browse path) and Type (OPC UA names, or PLC names such as DINT, REAL, BOOL). Optional: Elements, Mode, Min, Max, Step, Decimals, Unit, Description, Writable, Quality, Value (comma-separated for arrays), Period, Prob, Width. Column names are matched by name, in any order. A row the importer cannot use — an unknown type, a name that would be both folder and variable — is skipped and listed with the reason; the others are imported.

Every service call to every server is logged: the time, the client's address, the server, the service (OpenSecureChannel, CreateSession, ActivateSession, Browse, Read, Write, CreateSubscription, Publish and the rest), a detail such as the nodes touched, how many items, the result and the time it took. Pause stops the list moving while you read it; Clear empties it. The last entries are kept while the simulator runs; they are not written to disk.

• Methods, events and alarms, and history (HistoryRead).
• Custom structured data types, and any vendor's information model.
• Redundancy and registration with a discovery server.

A client that needs one of these will find it missing, as it would on a server that does not implement it; the request log shows the refused service.

• Modbus Logic OPC UA Explorer finds the simulated servers on this PC and the network, shows their endpoints as GetEndpoints reports them, and scans the address space with every variable's value, type, access and status. It is the client the simulator's own tests run with.
• Modbus Logic Edge Software: add an OPC UA Client node, enter the endpoint and the node ids (ns=1;s=PumpHouse.Pump1.Speed), and the gateway polls the simulator like a PLC. Mark variables writable to test writes from the gateway.
• Any other OPC UA client works the same way. A client that verifies server certificates will ask once to trust the simulator's self-signed certificate; a client that presents its own certificate is accepted automatically.

Without OPCUA_SIM_DATA the data folder is data next to the executable, or the user's application-data folder when that is not writable. On first start the executable unpacks itself into %LOCALAPPDATA%\TamidaS\OpcUaSimulator on Windows, ~/Library/Application Support/TamidaS/OpcUaSimulator on macOS and ~/.local/share/tamidas/opcua-simulator on Linux. Delete that folder to start clean.