python-fi50x

A transport-agnostic Python driver for the FI-50X UHF RFID reader (ISO-18000-6C / EPC Gen2) over its ASCII-over-UART protocol.

The library knows only the reader protocol — framing, the command set, typed responses, error-code handling and CRC-16 verification. It talks to a pluggable transport, so the same driver runs against a real serial port or a scripted fake in tests, and can be wrapped by any service (a RabbitMQ worker, a REST API, a CLI) on top.

• Import name: fi50x
• Distribution name: python-fi50x (like python-decouple → import decouple)

Features

• Inventory: single (Q) and multi-tag (U, U<slotQ>) EPC reads, drained to completion and de-duplicated
• Memory read/write (R/W) with correct hex address/length framing and word-length validation
• Tag management: access password (P), kill (K), lock/unlock (L), select/filter (T)
• Read-with-EPC (UR/QR), TX power and frequency-regulation get/set
• Typed results (Tag, ReadResult, WriteResult) and a typed exception hierarchy for reader error codes
• Gen2 CRC-16 verification of EPC reads
• TagTracker helper to turn inventory sweeps into new/lost tag events
• Thread-safe: a transport lock serialises full command/response transactions

Scope note: GPIO, frequency tuning, baud switching, command logging and the AA binary protocol are not implemented yet. See doc/PROTOCOL.md for the complete protocol reference.

Installation

pip install python-fi50x

Requires Python ≥ 3.8 and a serial connection to the reader (USB-UART). From source:

git clone https://github.com/pavelkim/python-fi50x
cd python-fi50x
pip install -e .[dev]

Quickstart

from fi50x import RFIDReader, Bank, Regulation

# Open the serial port (default baud 38400).
reader = RFIDReader.open("/dev/ttyUSB0")

print("firmware:", reader.firmware_version())
print("reader id:", reader.refresh_reader_id())

# Optional configuration
reader.set_regulation(Regulation.EU)   # 865–868 MHz
reader.set_power_dbm(20)               # register = dBm + 2, handled for you

# Inventory — read every tag currently in the field
for tag in reader.inventory().tags:
    print(tag.epc, "crc_ok" if tag.crc_valid else "crc?")

# Read 4 words of USER memory, then write two words back
data = reader.read(Bank.USER, address=0, length=4).data
reader.write(Bank.USER, address=0, data="DEADBEEF")   # leading zeros preserved

reader.close()

RFIDReader is also a context manager (with RFIDReader.open(port) as reader:). For tests or non-serial links, construct it directly with a Transport: RFIDReader(my_transport).

Continuous scanning with new/lost detection

from fi50x import RFIDReader, TagTracker

reader = RFIDReader.open("/dev/ttyUSB0")
tracker = TagTracker(miss_tolerance=2)   # tolerate a couple of missed sweeps

for result in reader.stream_inventory(interval=0.1):
    delta = tracker.update(tag.epc for tag in result.tags)
    for epc in delta.new:
        print("+ NEW ", epc)
    for epc in delta.lost:
        print("- LOST", epc)

A ready-to-run version of this is python-fi50x-scan.py:

./python-fi50x-scan.py --port /dev/ttyUSB0 --mode changes   # only new/lost tags
./python-fi50x-scan.py --port /dev/ttyUSB0 --mode stream     # every tag, every sweep
./python-fi50x-scan.py --help

Error handling

Reader error codes are raised as typed exceptions (all subclasses of ReaderError), so callers can react to specific conditions:

from fi50x import MemoryLockedError, InsufficientPowerError, NoTagError

try:
    reader.write(Bank.EPC, 2, "30001234")
except MemoryLockedError:
    ...   # bank is locked
except InsufficientPowerError:
    ...   # move the tag closer / raise power and retry
except NoTagError:
    ...   # nothing in the field

Configuration

The example script reads config from CLI flags, falling back to environment variables (a local .env is loaded if python-decouple is installed). See .env.example:

Development

pip install -e .[dev]
pytest                 # run the test suite (no hardware needed — uses a fake transport)
tox                    # test across Python versions
tox -e build           # build the sdist + wheel into dist/

Tests run entirely against a scripted FakeTransport, so no reader is required.

Protocol reference

The full FI-50X command specification — framing, every command, error codes, regulation and baud tables, examples and the Gen2 memory map — is in doc/PROTOCOL.md. Original vendor datasheets are in doc/.

License

MIT © Pavel Kim