sllurp is a Python library to interface with RFID readers. It is a pure-Python implementation of the Low Level Reader Protocol (LLRP).

These readers are known to work well with sllurp, but it should be adaptable with not much effort to other LLRP-compatible readers:

• Impinj Speedway (R1000)
• Impinj Speedway Revolution (R220, R420)
• Impinj Speedway xPortal
• Motorola MC9190-Z (handheld)
• Kathrein ARU2400
• Zebra FX9600

File an issue on GitHub_ if you would like help getting another kind of reader to work.

sllurp is distributed under version 3 of the GNU General Public License. See LICENSE.txt for details.

.. _GitHub: https://github.com/ransford/sllurp/

Branch modifications

This branch modifies the package heaviliy to make it suitable for fast re-configurations of the reader, i.e. connecting, changing a rospec parameter, inventoring, changing a rospec parameter, inventoring, ..., disconnecting.

As the twisted socket only allows one connection after import, we had to implement an own transport class using the standard socket of python. There is a new module reader where specific reader classes can inherit from the LLRPClient. We also modified the llrp, llrpproto and llrpdecoder modules to handle impinj specific extensions we need. Also, llrp_ is now completely rewritten to be state-less and does not depend on twisted. That way, the code is much cleaner and there is no hassle with chaining deferreds.

.. _reader: sllurp/reader.py .. _llrp: sllurp/llrp.py .. _llrp_proto: sllurp/llrp_proto.py .. _llrp_decoder: sllurp/llrp_decoder.py

Quick Start

.. code:: python

from sllurp.reader import R420

reader = R420('192.168.4.2')

freqs = reader.freq_table
powers = reader.power_table

tags = reader.detectTags(powerDBm=powers[-1], freqMHz=freqs[0], 
    mode=1002, session=2, population=1, duration=0.5, searchmode=2)

for tag in tags:
    print(tag)

Tag access

Example code for changing Tags EPC

.. code:: python

from sllurp.reader import R420
#import logging
#logging.basicConfig(filename='log.txt', level=logging.DEBUG)

reader = R420('192.168.4.2') # connect to reader

# setup access spec
epcLen = 12 # total number of bytes
epcRawStart = b'\x12\x34\x56\x78' # let the raw EPC URI start with these bytes
epcRawUri = epcRawStart+b'\x00'*(epcLen-len(epcRawStart)) # fill up with zeros
# note: 1 Word = 2 Bytes
writeSpecParam = {
    'OpSpecID': 0,
    'MB': 1,
    'WordPtr': 2,
    'AccessPassword': 0,
    'WriteDataWordCount': len(epcRawUri)//2,
    'WriteData': epcRawUri,
}
reader.startAccess(writeWords=writeSpecParam, opCount=0) # set opCount to 1 to stop after 1 write operation
# Actually adds and enables an access spec.
# It is executed with the next inventory round (reader.detectTags())

'''
readSpecParam = {
    'OpSpecID': 0,
    'MB': 1,
    'WordPtr': 0,
    'AccessPassword': 0,
    'WordCount': 8
}
reader.startAccess(readWords=readSpecParam)
'''

print('Before changing:')
tags = reader.detectTags(powerDBm=16, antennas=(1,)) # remove antennas argument or set to (0,) to use all antenna ports
for tag in tags:
    print(tag)
# At this point, the access spec is deleted

# Normal inventory
print('After changing:')
tags = reader.detectTags(powerDBm=16, antennas=(1,))
for tag in tags:
    print(tag)

Logging

.. code:: python

import logging

logging.basicConfig(filename='llrp.log', level=logging.DEBUG)

GUI

Currently, the GUI supports only the classes defined in reader_.

.. code:: python

from sllurp.gui import InventoryApp
app = InventoryApp() # start the GUI

The GUI can also be started with python -m sllurp.gui

Known Issues

Reader mode selection is confusing_, not least because the LLRP specification traditionally conflated ModeIndex and ModeIdentifier. If you're using sllurp inventory, you probably want to use --mode-identifier N instead of -mode-index. Check your reader's manual to see what mode identifiers it supports via the C1G2RFControl parameter, or run sllurp --debug inventory against a reader to see a dump of the supported modes in the capabilities description.

.. _confusing: https://github.com/ransford/sllurp/issues/63#issuecomment-309233937

Contributing

Want to contribute? Here are some areas that need improvement:

• Reduce redundancy in the encode_* and decode_* functions in llrp_proto.py.
• Support the AccessSpec primitive (basis for tag read and write).
• Write tests for common encoding and decoding tasks.
• Make get_reader_config use the fabric library to connect to readers via SSH.
• Generalize LLRP support beyond Impinj readers. Remove Impinj-specific assumptions.

Authors

Much of the code in sllurp is by Ben Ransford, although it began its life in August 2013 as a fork of LLRPyC. Many fine citizens of GitHub have contributed code to sllurp since the fork.

.. _Ben Ransford: https://ben.ransford.org/ .. _LLRPyC: https://sourceforge.net/projects/llrpyc/