# Timing and retries

## Node-bus timeout targets

The protocol assigns these master-side limits:

| Operation | Timeout |
|---|---:|
| Standard command | 10 ms |
| Ping | 400 µs |
| Flash or firmware upgrade | 3 s |

After a timeout the master retries according to its policy; after retries are
exhausted the node is treated as unavailable. These are RS-485 transaction
targets. Ethernet transport adds its own UDP timeout and retry layer.

## Responsiveness

Nodes should answer ordinary requests promptly and must not keep interrupts
disabled for long periods. Firmware should return a ping ACK
within 100 µs. Long flash operations are the explicit exception and therefore
have their own timeout class.