Campbell CR800 Series - Voltage Measurement Mechanics

Section 8. Operation
348
FIGURE 78: PGIA with Input Signal Decomposition
8.1.2.7.2 Voltage Measurement Mechanics
Measurement Sequence
An analog voltage measurement as illustrated in the figure Simplified Voltage
Measurement Sequence
(p. 348), proceeds as follows:
1. Switch
2. Settle
3. Amplify
4. Integrate
5. A to D (successive approximation)
6. Measurement scaled with multiplier and offset
7. Scaled value placed in memory
FIGURE 79: Simplified voltage measurement sequence.
Voltage measurements are made using a successive approximation A-to-D (p. 489)
converter to achieve a resolution of 14 bits. Prior to the A-to-D, a high
impedance programmable-gain instrumentation amplifier (PGIA) amplifies the
signal. See figure Programmable Gain Input Amplifier (PGIA)
(p. 349). The
CRBasic program controls amplifier gain and configuration — either single-ended