Measurement - Hitachi 902 Service Manual

7.2 Measurement

(1) Forty-nine cells are measured in each cycle.
(2) Thirty-nine measurements (4 cell blank measurements, 35 sample absorbance
measurements) are made in each cycle.
(3) In case of at least one ADC failure in thirty-nine measurements, data is 0 and ADC alarm
is added.
(4) ADC
(a) Time: Refer to the description of ADC parameters.
(b) Calibration equation
ABS in terms of 10 mm cell
(measured with 6 mm cell)
A = Calibrated ADC count for 2 V voltage
B = Calibrated ADC count for 6 V voltage
C = Measured ADC count
(c) Immediately after calibration, subtraction is made atB initialization, resetting upon
operation start and T/M resetting. Note, however, that data at initialization is
discarded.
At this time, ADC CALIB alarm is issued if A or B is out of the range given below.
7546 ≤ A ≤ 8341
22640 ≥ B ≥ 25023
(d) Number of conversion bits: 16 bits
(e) The RESET command is issued to the ADC controller at initialization and T/M
resetting.
16667
× =
100 000 , X
−
B A
7 - 13
−
63338 B 25000 A
−
B A