Custom (Serial)
The Custom (Serial) entry is the registry's last-resort fallback for in-house, white-label, or non-listed devices that speak a serial-compatible fiscal protocol. It exists so that an integrator can bring up a previously-unsupported AMEF without waiting for a registry entry — at the cost of manual configuration and no auto-detect guarantees. By design it sits at the bottom of the probe order so it is matched only when nothing else claims the connection.
At a glance
| Protocol id | Family | Default TCP port | Default baud | Transports | Probe order |
|---|---|---|---|---|---|
custom.serial | custom | 8000 | 9600 | Serial, TCP | 11 |
Choose a transport
Custom is the only protocol in the registry that does not advertise Bluetooth — the supported set is Serial and TCP only. If you need a Bluetooth-capable fallback, you have to use one of the listed protocols instead. USB-attached devices, as everywhere else in the registry, are reached through a USB-to-Serial bridge (CDC-ACM or FTDI) and addressed as Serial. Wi-Fi is not a supported transport; see the Wi-Fi note in Supported devices.
Use the connection defaults
The defaults — TCP port 8000 and 9600 baud — are conservative starting points that work with the widest range of off-the-shelf fiscal hardware. Both should be expected to need overriding for any specific device: consult the device's protocol manual and set port, baud, and any framing options manually during pairing.
Watch for known quirks
If the device works under Custom but you expect to deploy it at scale, please request a first-class registry entry — see the Requesting a new device section in Supported devices.
Pair the printer manually
Custom pairing is the only flow that materially differs from the standard one: instead of accepting auto-detect, you choose Serial or TCP explicitly, then enter port, baud, and (for Serial) any framing options the device requires. Test prints will surface the most common misconfigurations (wrong baud, wrong framing, wrong port). The full walkthrough is in Pairing your fiscal printer.
Next steps
- Supported devices — full compatibility matrix and request-a-device guidance.
- Pairing your fiscal printer — operational pairing flow on Android.
- Troubleshooting — when a paired device goes offline or refuses to print.