Unihedron SQM-LU-DL, Operator'S Manual

Page: 66 / 101

8 Commands and responses
Table 8.4: Unaveraged reading request response
Column Example value Description
0
u
Indicates that a reading is being returned.
2-8
06.70m
Reading in
mag
arcsec 2
.
Leading space for positive value.
Leading negative sign (-) for negative value.
A reading of
0.00m
means that the light at the sensor has reached
the upper brightness limit of the unit.
10-21
0000022921Hz
Frequency of sensor in Hz.
23-33
0000000020c
Period of sensor in counts. Counts occur at a rate of 460.8 kHz
(14.7456MHz/32).
35-46
0000000.000s
Period of sensor in seconds with millisecond resolution. Determined
by dividing the above counts value by 460800.
48-54
039.4C
Temperature measured at light sensor in degrees C.
Leading space for positive value.
Leading negative sign (-) for negative value.
55-56 Carriage return (0x0d), Line feed (0x0a).
An example of the response is:
u, 06.70m,0000022921Hz,0000000020c,0000000.000s, 039.4C
0123456789 123456789 123456789 123456789 123456789 123456
Future versions of this reading string will only modify reported values beyond position 54. Characters 0 to 54 may be
considered stable.
8.2.3 Linear reading request
The “linear reading” request “
rfx
” commands the meter to provide the current brightness value proportional to the light
flux or frequency output from the light sensor. This value is compensated for only by the dark current frequency.
f
out
= f
light
−
f
dark
To allow for long period measurements, the output integer value is scaled up by a factor of 45,000.
n
out
= f
out
×
45000
The format of the response is shown in table 8.5:
Table 8.5: Linear reading request response
Column Example value Description
0-1
f,
Indicates that a frequency reading is being returned.
Table continued on next page ...
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Unihedron SQM-LU-DL Operator’s Manual -
20220119