Testing & diagnosing connections

The Test button

Every connection has a Test button that runs a one-shot connection attempt and reports round-trip latency on success or the error on failure, without enabling the connection or touching your variables. Use it after every settings change.

Status indicators

The Connections sidebar shows a live status dot per connection (green = connected, red = failing) along with the last error message and last-connected time in the properties panel.

Fault-finding checklist

Work down; each step assumes the previous passed.

1. Ping the PLC from your PC. No reply → networking (subnet, cable, firewall), not the twin.
2. Test the connection.
   • Timeout → wrong IP, or a firewall dropping the port (S7: TCP 102 · ADS: TCP 48898 · UA: the endpoint port, typically 4840).
   • Refused / rejected → reached the device, but: S7 → PUT/GET not permitted or wrong rack/slot; ADS → missing route or wrong AMS Net ID/port; UA → security policy/mode mismatch or bad credentials.
3. Connection green but a variable reads nothing → the address: typo, S7 DB still optimized, symbol not in the ADS symbol table, or wrong UA namespace index.
4. Value updates but is nonsense → data type mismatch, or a missing unit conversion.
5. Motion is stuttery → polling interval too slow for the axis; drop it to 50–100 ms.

Still stuck? Signal trace confirms whether the raw value is arriving before you debug the scene side, and Troubleshooting covers the non-PLC failure modes.