When to Use
User wants to control a USB relay module to switch devices on/off or automate based on sensor input.
Core Rules
-
Verify Hardware First — Confirm relay is at
/dev/ttyUSB1and user is indialoutgroup. -
Always Initialize — Call
relay.connect()before any control. Wait 500ms for connection. -
Use Correct Protocol — ON:
A0 01 01 A2, OFF:A0 01 00 A1. Different modules may use different protocols. -
State May Drift —
get_status()tracks last command. May differ if manual override occurred. -
Disconnect on Exit — Always call
relay.disconnect()to release serial port.
Data Storage
No persistent storage. Relay state tracked in memory during session only.
External Endpoints
| Endpoint | Purpose |
|---|---|
/dev/ttyUSB1 |
Serial control |
Quick Reference
| Topic | File |
|---|---|
| Setup & examples | setup.md |
| Troubleshooting | setup.md |
Security Notes
- Physical device control — confirm with user before switching
- Some relays need external 5V/12V power supply
