Z-World Wolf BL2600, Руководство пользователя

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24 Wolf (BL2600)
3.4 A/D Converter Inputs
The single A/D converter chip used in the BL2600 has a resolution of 12 bits (11 bits for the
value and one bit for the polarity). The A/D converter chip has a programmable amplifier.
Each external input has circuitry that provides scaling and filtering. All 8 external inputs
are scaled and filtered to provide the user with an input impedance of 1 M
Ω
and a variety
of single-ended unipolar, single-ended bipolar, and differential bipolar ranges as shown in
Table 7.
Figure 16 shows a pair of A/D converter input circuits. The resistors form an approx. 10:1
attenuator, and the capacitors filter noise pulses from the A/D converter inputs.
Figure 16. Buffered A/D Converter Inputs
The A/D converter chip can only accept positive voltages. By pairing the analog inputs and
setting the reference voltage from the D/A converter [0 V for single-ended unipolar or dif-
ferential measurements, V = (voltage range) ÷ 9 for single-ended bipolar measurements],
single-ended unipolar, single-ended bipolar, differential bipolar, or current (4–20 mA on
channels 0–3 only) measurements are possible, and can be configured for each channel or
channel pair with the
opmode
parameter in the
anaInConfig
software function call.
Adjacent A/D converter inputs are paired to make bipolar measurements. The default
setup is to measure only voltages for the ranges listed in Table 7.
ADC
1 M W
1 nF
AIN0
AGND
+ V
AIN1
1 nF
Ref. Voltage
from D/A Converter
105 k W
105 k W