Section 8. Operation
393
The rate at which the signal settles is determined by the input settling time
constant, which is a function of both the source resistance and fixed-input
capacitance (4.7 nfd) of the CR6.
Rise and decay waveforms are exponential. Figure
Input Voltage Rise and
Transient Decay
(p. 393)
shows rising and decaying waveforms settling closer to the
true signal magnitude, V
so
. The
SettlingTime
parameter of an analog
measurement instruction allows tailoring of measurement instruction settling
times with 100 µs resolution up to 600000 µs.
Settling times are listed in table
CRBasic Measurement Settling Times
(p. 393).
Default settling times (those resulting when
SettlingTime
=
0
) provide sufficient
settling in most cases. Additional settling time is often programmed when
measuring high-resistance (high-impedance) sensors or when sensors connect to
the input terminals by long leads.
Measurement time of a given instruction increases with increasing settling time.
For example, a 1 ms increase in settling time for a bridge instruction with input
reversal and excitation reversal results in a 4 ms increase in time for the CR6 to
perform the instruction.
FIGURE 84: Input voltage rise and transient decay
b
CRBasic Measurement Settling Times
SettlingTime
Argument
Resultant Settling Time
1
0
500 µs
integer between
100
and
600000
,
inclusive
μs entered in
SettlingTime
argument
1
500 µs is the default voltage measurement settling time.
Settling Errors
When sensors require long lead lengths, use the following general practices to
minimize settling errors:
•
Do not use wire with PVC-insulated conductors. PVC has a high
dielectric constant, which extends input settling time.
Summary of Contents for CR6 Series
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Page 76: ...Section 5 Overview 76 FIGURE 20 Half Bridge Wiring Example Wind Vane Potentiometer ...
Page 80: ...Section 5 Overview 80 FIGURE 23 Pulse Input Wiring Example Anemometer ...
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Page 454: ...Section 8 Operation 454 FIGURE 104 Narrow Sweep High Noise ...
Page 459: ...Section 8 Operation 459 FIGURE 106 Vibrating Wire Sensor Calibration Report ...
Page 535: ...Section 8 Operation 535 8 11 2 Data Display FIGURE 121 CR1000KD Displaying Data ...
Page 537: ...Section 8 Operation 537 FIGURE 123 CR1000KD Real Time Custom ...
Page 538: ...Section 8 Operation 538 8 11 2 3 Final Storage Data FIGURE 124 CR1000KD Final Storage Data ...
Page 539: ...Section 8 Operation 539 8 11 3 Run Stop Program FIGURE 125 CR1000KD Run Stop Program ...
Page 541: ...Section 8 Operation 541 FIGURE 127 CR1000KD File Edit ...
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Page 610: ...Section 11 Glossary 610 FIGURE 137 Relationships of Accuracy Precision and Resolution ...
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