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Last active December 3, 2020 07:46
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How to decompress a Loxone sps0.LoxCC File
#!/usr/bin/env python
# -*- coding: utf-8 -*-
import struct
import ftplib
import zipfile
import StringIO
loxoneMiniServerIP = '' # IP address of the Loxone Miniserver
adminUsername = '<ADMIN_USERNAME>'
adminPassword = '<ADMIN_PASSWORD>'
ftp = ftplib.FTP(loxoneMiniServerIP)
ftp.login(adminUsername, adminPassword)
data = []
def handle_binary(more_data):
resp = ftp.retrbinary("RETR /backup/", callback=handle_binary)
data = "".join(data)
zf = zipfile.ZipFile(StringIO.StringIO(data))
with'sps0.LoxCC') as f:
header, = struct.unpack('<L',
if header == 0xaabbccee: # magic word to detect a compressed file
compressedSize,header3,header4, = struct.unpack('<LLL',
# header3 is roughly the length of the uncompressed data, but it is a bit higher
# header4 could be a checksum, I don't know
data =
index = 0
resultStr = ''
while index<len(data):
# the first byte contains the number of bytes to copy in the upper
# nibble. If this nibble is 15, then another byte follows with
# the remainder of bytes to copy. (Comment: it might be possible that
# it follows the same scheme as below, which means: if more than
# 255+15 bytes need to be copied, another 0xff byte follows and so on)
byte, = struct.unpack('<B', data[index:index+1])
index += 1
copyBytes = byte >> 4
byte &= 0xf
if copyBytes == 15:
copyBytes += ord(data[index])
index += 1
if copyBytes > 0:
resultStr += data[index:index+copyBytes]
index += copyBytes
if index >= len(data):
# Reference to data which already was copied into the result.
# bytesBack is the offset from the end of the string
bytesBack, = struct.unpack('<H', data[index:index+2])
index += 2
# the number of bytes to be transferred is at least 4 plus the lower
# nibble of the package header.
bytesBackCopied = 4 + byte
if byte == 15:
# if the header was 15, then more than 19 bytes need to be copied.
while True:
val, = struct.unpack('<B', data[index:index+1])
bytesBackCopied += val
index += 1
if val != 0xff:
# Duplicating the last byte in the buffer multiple times is possible,
# so we need to account for that.
while bytesBackCopied > 0:
if -bytesBack+1 == 0:
resultStr += resultStr[-bytesBack:]
resultStr += resultStr[-bytesBack:-bytesBack+1]
bytesBackCopied -= 1
with open('Project.Loxone', "w") as f:
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sarnau commented Mar 16, 2018

I've quickly updated to download the last backup directly from the Loxone MiniServer to get the *.Loxone project file.

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