Troubleshooting

This page covers common issues you may encounter in Sim Assist, along with their solutions, performance optimization tips, and browser compatibility information.

Common Issues

Simulation Won't Start

• No program assigned — Ensure your project has at least one PLC program and it is assigned to a task. Check Project Settings → Tasks.
• Compilation errors — Open the Problems panel at the bottom of the editor. Fix all errors before starting the simulation. Warnings do not prevent execution but should be reviewed.
• Missing I/O bindings — If your program references variables that are not bound to scene objects, the simulation may refuse to start. Check the I/O Mapping panel for unresolved bindings.

OPC UA Connection Fails

• Verify the endpoint URL includes the correct protocol, IP address, and port (e.g., opc.tcp://192.168.1.100:4840).
• Check that the bridge server is running and reachable from your browser.
• Ensure the PLC's OPC UA server is active and accepting connections.
• For secured connections, confirm the Sim Assist client certificate is trusted on the PLC. See the OPC UA Integration page for detailed steps.

3D Model Import Errors

• Unsupported format — Sim Assist supports glTF (.gltf, .glb), FBX, OBJ, and STEP formats. Convert your model if it uses a different format.
• File too large — Models over 50 MB may fail to upload. Reduce polygon count or split the model into smaller parts.
• Missing textures — When importing glTF or OBJ files, ensure texture files are included in the same directory or embedded in the file. Use .glb format to bundle everything into a single file.
• Incorrect scale — If your model appears extremely large or small, check the export units from your CAD software. Sim Assist uses meters as the base unit.

Variables Not Updating During Simulation

• Confirm the variable is not being overwritten by another part of your program later in the scan cycle.
• Check if the variable is forced to a fixed value in the watch panel (indicated by an orange highlight).
• Verify the I/O binding direction — an output variable must be bound as an output, not an input.

Performance Optimization

If the simulation runs slowly or the 3D viewport stutters:

• Reduce polygon count — Simplify 3D models before importing. Use your CAD software's decimation or simplification tools. Aim for under 500,000 total polygons in a scene.
• Limit physics bodies — Each object with physics enabled adds computational load. Only enable physics on objects that need collision detection or movement.
• Close unused browser tabs — Other tabs consume memory and CPU that the simulation needs.
• Increase cycle time — If your PLC logic does not require fast execution, increase the cycle time from 10 ms to 50 ms or 100 ms. This frees CPU for rendering.
• Disable shadows — In View → Rendering Settings, turn off dynamic shadows for a noticeable framerate improvement.
• Use instancing — If your scene has many identical objects (e.g., boxes on a conveyor), use the instance feature instead of individual copies. Instances share geometry data and render much faster.

Browser Compatibility

Sim Assist is a browser-based application with the following requirements:

To check your browser's capabilities, visit Settings → System Info within Sim Assist. This page runs a compatibility check and reports any issues.

Known Browser-Specific Issues

• Safari — WebGL performance is lower than Chromium-based browsers. Complex scenes may stutter.
• Firefox — Large model imports may be slower due to differences in the JavaScript engine's handling of binary data.
• Incognito/Private mode — Storage quotas are reduced, which can cause issues with large projects. Use normal browsing mode.

Getting Help

If you cannot resolve an issue using this guide:

• Community Forum — Search or post in the Sim Assist community forum. Other users and team members actively answer questions.
• Support — Contact the support team through Help → Contact Support in the application. Include your browser version, a description of the issue, and any error messages from the browser console (F12 → Console tab).
• Documentation — Browse the full documentation for detailed guides on each feature.