[BUG] dSPACE reconnection after TrafficLayer restart - needs testing

[yunlishao]

Describe the bug
Need to verify if dSPACE/Simulink client can properly reconnect to TrafficLayer after restart. Previously, reconnection failed after first use. Issue #66 added graceful shutdown, but unclear if this fully resolves dSPACE reconnection.

To Reproduce

1. Start TrafficLayer.exe with EnableXil: true (XIL port 420)
2. Connect dSPACE/Simulink model - verify simulation works
3. Stop Simulink model
4. Close TrafficLayer.exe (any method)
5. Restart TrafficLayer.exe
6. Attempt to reconnect Simulink model
7. Check if connection succeeds or fails

Expected Behavior
After #66 graceful shutdown, dSPACE should reconnect without errors.

Investigation Needed

• Test reconnection with current code (post PR #66/graceful shutdown #74)
• Verify shutdown signal (state=0) reaches XIL clients
• Check Simulink S-function handles shutdown properly
• Verify socket cleanup on both sides

Environment

• MATLAB/Simulink/dSPACE version: 2024a
• SUMO version: 1.21

Additional context
Related to closed #66 (graceful shutdown). May need dSPACE-side socket cleanup or SO_REUSEADDR configuration. Test with config_RS_SimulinkRS.yaml.

[yunlishao]

Progress Update

With the graceful shutdown of TrafficLayer and SUMO now implemented, we can successfully re-establish connections.

What's the remaining piece we didn't realize last time

The only missing piece is in the generateTimeStepTrigger function:

• The timeInPrevious variable needs to be reset when connectionState is not 3 (not connected)
• This ensures the timing logic restarts cleanly on reconnection

What's Working

After fixing this function, we can

• Disconnect and reconnect as many times as needed
• Graceful shutdown helps ensure clean disconnection on both sides

Next Steps

Need to cleanup the Simulink block to properly handle this timing reset, then we can close this issue and the associated PR.

Verified through testing that multiple disconnect/reconnect cycles now work correctly.

[yunlishao]

Suggestion: Convert RealSim Core to Library Block

RealSim components are currently embedded in template models. Converting to a Simulink library block would:

• ✅ Propagate bug fixes (like reconnection handling) automatically to all test scenarios
• ✅ Prevent accidental user modifications to core components
• ✅ Ensure consistent behavior across dSPACE and standard Simulink
• ✅ Simplify debugging by isolating core vs. user code

Implementation: Create CommonLib/RealSimLibrary.slx with locked, masked subsystems. Templates reference library blocks instead of embedded copies.