Campbell CR6 Series, Руководство оператора

Страница: 420 / 690

Section 8. Operation
420
If the Reps parameter in a voltage measurement instruction is > 1, the
measurements are on sequential input terminals can be made with a single setting
of the A-to-D. About 6 ms are required to wake-up the A-to-D converter at the
start of a scan, so the first measurement takes longer than subsequent
measurements of the same type in a scan.
See table Parameters That Control Measurement Sequence and Timing
(p. 420).
FIGURE 89: Programmable Gain Input Amplifier (PGIA):
H to V+, L to V–, VH to V+, VL to V– correspond to
text.
A voltage measurement proceeds as follows:
1. Set PGIA gain for the voltage range selected with the CRBasic measurement
instruction parameter Range . Set the A-to-D converter for the first notch
frequency selected with fN1 . See First-Notch Frequency (Digital Filter
(p. 421))
.
2. Turn on excitation to the level selected with ExmV or ExuA .
3. Multiplex selected terminals ( InChan ) to the PGIA and delay for the entered
settling time ( SettlingTime ).
4. Perform the A-to-D conversion.
5. Repeat for excitation reversal and input reversal as determined by parameters
RevEx and RevDiff .
6. Apply multitplier ( Mult ) and offset ( Offset ) to measured result.
See
Basic Voltage Measurements — Specifications
(p. 102)
for measurement speeds.