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Troubleshooting & FAQ

Connection Issues​

"Connection refused"​

Cause: Controller is not reachable or wrong port.

Solutions:

  • Verify the controller's IP address and port
  • Check that the controller is powered on and connected to the network
  • Verify no firewall is blocking TCP port 4545 (or your configured port)
  • Try pinging the controller: ping <IP address>

"Connection timed out"​

Cause: Network path issue or controller not responding.

Solutions:

  • Check physical network connectivity (cable, switch, Wi-Fi)
  • Verify you're on the same network/VLAN as the controller
  • Try a longer timeout in the Keep Alive field

Connection drops after a few seconds​

Cause: Keep-alive messages not being sent or controller timeout is shorter than expected.

Solutions:

  • Ensure Keep Alive Time is set to 10 seconds or less
  • Check that the controller's expected keep-alive interval matches your setting
  • Look at the log for MID 9999 messages — they should appear at the configured interval

No response to MID 0001​

Cause: Wrong protocol variant selected.

Solutions:

  • Try a different variant (Rexroth, BMW, Ford)
  • Check the controller documentation for the correct variant
  • Look at the raw bytes in the log — if the header looks scrambled, the variant is likely wrong

MID Panel Issues​

"DocumentedPossibleErrors" appears in sent messages​

Known issue: The Open Protocol Interpreter library (v6.1.1) adds error metadata to sent MIDs. This is cosmetic and does not affect the actual message sent to the controller.

Fields don't match my controller​

Solution: Try a different revision in the MID panel's revision dropdown. Different controller firmware versions support different revisions with different field sets.

Scripting Issues​

"function main() not found"​

Cause: Your script doesn't define a main() function.

Solution: Every script must have:

function main()
    -- your code here
end

"attempt to call a nil value"​

Cause: Calling a method that doesn't exist or using wrong syntax.

Solutions:

  • Use colon syntax for method calls: session:Connect() not session.Connect()
  • Check spelling of method names against the API Reference
  • Ensure session, log, and assert are lowercase

Script hangs / doesn't complete​

Causes:

  • WaitForMid() waiting for a MID that never arrives
  • Infinite loop in your script

Solutions:

  • Click Stop to cancel the test
  • Use reasonable timeouts (5000–30000ms)
  • Use TryWaitForRawResponse() instead of WaitForRawResponse() if timeout is expected
  • Add log:Info() calls to track where the script is stuck

LSP diagnostics not working​

Cause: lua-language-server binary missing or corrupted.

Solution: Reinstall the application — the installer automatically deploys the language server.

Then restart the Test Suites window.

Log Issues​

Log is too cluttered​

Solutions:

  • Enable Hide Alive to filter out MID 9998/9999 keep-alive messages
  • Use Wireshark mode to focus on individual message details
  • Clear the log periodically

Log entries disappear​

Expected behavior: The log auto-trims at 11,000 entries, keeping the most recent 10,000.

General Issues​

Application won't start​

Solutions:

  • Verify .NET 8 Desktop Runtime is installed: dotnet --list-runtimes
  • Reinstall from the installer (it will download the runtime if missing)

"Demo features disabled" message​

Solution: Load a license file. See Licensing.

High DPI display issues​

The application supports DPI-aware scaling. If panels appear too small or too large:

  • Check Windows display scaling settings (Settings → Display → Scale)
  • The application respects the system DPI setting

FAQ​

Q: Can I connect to multiple controllers simultaneously? A: The main application connects to one controller at a time. However, Lua scripts can create multiple independent sessions using createSession().

Q: Which Open Protocol versions are supported? A: The application supports Open Protocol with Rexroth, BMW, and Ford header variants. 78 MIDs are implemented across 23 groups.

Q: Can I save my panel layout? A: Panel positions are saved automatically when you close the application.

Q: Where are my test scripts stored? A: %APPDATA%\Haller + Erne GmbH\heOPTester\Tests\

Q: Can I use external Lua libraries? A: Only in Unrestricted Mode (per workspace). Enable it in the Test Suites toolbar. Standard mode blocks require, io, and os for security.

Q: What's the maximum number of concurrent tests? A: 5 concurrent test runs, each with its own TCP connection.

Q: How do I export test results for CI/CD? A: Use Generate Report → JUnit XML. This format is compatible with Jenkins, GitHub Actions, and most CI systems.