Supported hardware
Adapters and device requirements
Check this before buying anything. The adapter and the Android device both have to be right, and the USB requirement rules out some phones entirely.
Android device
What the phone or tablet needs
| Requirement | Detail |
|---|---|
| Android 11+ | Older releases are not supported. |
| USB OTG / host mode | Required for any USB adapter. ProtocolWatcher declares USB host as a required feature, so Google Play hides the app on devices without it. |
| Bluetooth | Needed for Bluetooth Classic (SPP) and Bluetooth LE adapters. No USB support required. |
| Wi-Fi | Needed for Wi-Fi/TCP adapters and Modbus TCP. No USB support required. |
CAN
CAN and CAN FD adapters
| Adapter | Connection | Notes |
|---|---|---|
| PEAK PCAN-USB | USB (OTG required) | Classic CAN. Industrial-grade; the reference choice for work that has to hold up under scrutiny. |
| PEAK PCAN-USB FD | USB (OTG required) | Classic CAN and CAN FD. |
| CANable / SLCAN-class | USB (OTG required) | Inexpensive open hardware speaking the SLCAN protocol. Suitable for monitoring, transmit and DBC-decoded work; firmware quality varies between clones. |
Heavy vehicles usually present a 9-pin Deutsch (J1939-13) connector rather than the 16-pin OBD-II socket, so budget for the right cable as well as the adapter.
OBD-II
ELM327 interfaces
| Transport | Connection | Notes |
|---|---|---|
| ELM327 USB | USB (OTG required) | Wired, lowest latency of the four. |
| ELM327 Bluetooth Classic | Bluetooth SPP | No USB support needed on the device. |
| ELM327 Bluetooth LE | BLE | No USB support needed on the device. |
| ELM327 Wi-Fi | TCP over Wi-Fi | No USB support needed on the device. |
ELM327 clones vary widely in firmware quality. They are fine for OBD-II; CAN and UDS work should use a real CAN adapter, which the app talks to directly.
Modbus and serial
Serial links
| Link | Connection | Notes |
|---|---|---|
| Modbus RTU | USB serial or Bluetooth serial | USB variants need OTG. |
| Modbus TCP | Network | No adapter hardware required. |
| Raw serial | USB, Bluetooth SPP/BLE, or TCP | Configurable framing. |
No hardware yet
Evaluate before you buy
Demo Mode simulates every protocol, so you can work through the live monitor, decode views, filtering and export before choosing an adapter.