TSI Incorporated 8587A, Operation And Service Manual

Page: 30 / 85

3-8 Model 8587A Laser Photometer
Hex Data Retrieval
The voltage data is passed from the instrument as a string of 8
hexadecimal characters in ASCII
when the “D” serial command is received.
This number must be converted to decimal and then be divided by 10
7
to
obtain the true signal voltage reading matching the front panel reading. The
process is outlined in the example below:
0 A 4 6 C 3 D 8
Hex
Character
Received
Decimal Value
1
st
0 0 x 16
7
= 0
2
nd
0 0 x 16
6
= 0
3
rd
4 4 x 16
5
= 4194304
4
th
6 6 x 16
4
= 393216
5
th
C 12 x 16
3
= 49152
6
th
3 3 x 16
2
= 768
7
th
D 13 x 16
1
= 208
8
th
8 8 x 16
0
= 8
The sum of the numbers divided by 10
7
= 0.4637656 volts.
The voltage data string which is returned after the “D” command is sent
represents a continuous average since the last time the voltage was read,
or since the last reset "R" string was sent to the Laser Photometer.
A “D”
command also resets the average after data is sent.
Decimal Data Retrieval
When a “K” command is passed to the Laser Photometer, the signal
voltage data is returned as a string of 8 ASCII characters in scientific
notation, having five characters of mantissa, a sign (±), and a two character
exponent:
Decimal voltage data is presented in the following 8 character string
example:
3 . 7 6 E
– 0 3
These eight characters translate to 3.76

10
-3
or 0.00376 volts.
The voltage data strin
g which is returned after the “K” command is sent
represents a continuous average since the last time the voltage was read
with the “K” or “D” command, or since the last reset "R" string was sent to
the Laser Photometer.