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Modbus TCP Simulator in 5 Minutes with SPX: Quickstart

This is a hands-on quickstart. For a technical overview of register maps, scaling, endianness, scenarios, and automation workflows, see Modbus Simulator.

Simulation timeline for the “Auto Heat Step” scenario — spx_eurotherm_3216_temp. The model emulates a Eurotherm 3216 PID temperature controller, streaming realistic process and sensor values so you can validate live updates, alarm/limit behavior, and downstream automation responses during rapid setpoint changes and transient conditions.
Simulation timeline for the “Auto Heat Step” scenario — spx_eurotherm_3216_temp. The model emulates a Eurotherm 3216 PID temperature controller, streaming realistic process and sensor values so you can validate live updates, alarm/limit behavior, and downstream automation responses during rapid setpoint changes and transient conditions.

In this quickstart you’ll launch a realistic Modbus TCP device simulation in about five minutes using SPX. The flow is intentionally simple: download the SPX package, run the setup wizard, start the local stack, open the SPX UI, select a ready-made Modbus TCP instance, and verify it using a standard Modbus client tool. The result is a repeatable “virtual device lab” environment you can use for integration testing, demos, and regression baselines without a hardware lab.


Tip #1 - Install SPX and select Smart Building Pack


  1. Get your Product Key + installer package

    1. Log in and open Product & Keys: https://www.simplephysx.com/keys

    2. Copy your SPX Product Key

    3. Download the installer package (e.g. spx-examples-<version>.zip)

  2. Extract the ZIP

    1. Unzip the package into a dedicated folder (e.g. spx-examples-<version>/). You should see platform launchers like spx-setup.*.

  3. Run the Setup Wizard (spx-setup.*)

    1. From the extracted folder, start the launcher for your OS:

      1. Windows: double-click spx-setup.bat

      2. macOS: double-click spx-setup.command

      3. Linux desktop: double-click spx-setup.desktop

      4. Terminal (macOS/Linux): ./spx-setup.sh

  4. In the wizard: select Industrial Pack + paste your key

    1. Select Industrial Pack (ENTER accepts recommended defaults)

      Terminal window displaying four software package options with details on protocols and services. Prompt for package selection.

    2. Paste your SPX Product Key when prompted

      Terminal window showing SPX installation script with protocol options, package numbers, and SPX Product Key prompt on a dark background.

    3. Review the summary and choose Start the stack now

    Note: For the full, always up-to-date installation instructions (including prerequisites and OS-specific launchers), see the SPX Installation Guide in the docs: https://docs.simplephysx.com/getting-started/installation-guide.

Tip #2 - Open the SPX UI


Industrial Pack instances list in the SPX web UI on localhost:3000, showing available simulator instances including spx_s7_1500_process_cell.
SPX web UI (localhost:3000): Industrial Pack instance catalog — choose a ready-to-run simulator such as spx_eurotherm_3216_temp.

You should see the SPX interface with a list of available instances from the Industrial Pack.


Tip #3 - Start the Modbus TCP simulator instance


  • From the list of available instances, select:

    spx_s7_1500_process_cell


Dashboard showing 5 instances running with names and models listed. A red arrow points to an edit icon beside the last instance.
From the Industrial Pack list, select spx_eurotherm_3216_temp and click Open/View Instance to access the instance details and controls.

  • Open the instance and confirm:

    • Status: Running

    • Modbus TCP connection details (host/port)

    • A register/attribute view (values visible and updating if the model is dynamic)

Tip: If the model includes physics-driven behavior or scenarios, register values can evolve realistically over time.

Dashboard showing process data graph with temperature, pump speed, and flow metrics. Various colored lines on the graph indicate changes over time.
Instance details for spx_eurotherm_3216_temp — status, OPC UA connection info, live attributes, and scenario controls (e.g., HeatUp Cycle*) in one place.*

Tip #4 - Verify it with a Modbus client


To validate the simulator is live, connect using any Modbus TCP client, for example:

• QModMaster (free, cross-platform)

• Modbus Poll (Windows)

• your gateway / SCADA / HMI software


Use the connection details from SPX instance view, typically:

  • Host: localhost

  • Port: [PORT from the SPX instance] (often 502, but use the value shown in SPX)


Dashboard interface with a communication table on the left and a graph on the right. Red arrow points at port value 5029. The mood is technical.

In your Modbus client:

  1. Connect to the Modbus TCP server

  2. Read a few registers (holding registers are a common starting point)

  3. Confirm values are returned consistently

  4. If the model supports it, write a value and observe the state change (optional)



Expected outcome (what “done” looks like)


You can read (and optionally write) registers reliably, confirming the simulator behaves like a real Modbus TCP device.


Next: customize and extend (coming next)


Next we’ll take this same instance and:


  • Tweak the model in the editor and reload it

  • Generate a new variant via an LLM workflow

  • Run scenario-driven tests and capture reproducible baselines


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