Documentation update: An uncalibrated SQM-LU-DL unit may respond to the "Return one logged record" with a leading mpsas negative sign:
Uncalibrated (negative sign):
Sent: L40000000001x To: /dev/ttyUSB1 Received: L4,00-01-01 1 01:00:01,-11.52, 019.3C,225
Calibrated (no negative sign):
Sent: L40000000011x To: /dev/ttyUSB1 Received: L4,00-01-01 1 00:00:21,08.51, 018.6C,222
This means that there may be one extra character (negative sign) in the response field. Comma separation is the better choice when parsing this response.
Updated manual here, see section 4.2.13.5:
http://unihedron.com/projects/darksky/cd/SQM-LU-DL/SQM-LU-DL_Users_manual.pdf
