Campbell Scientific CR6 CR6 Measurement and Control System - Page 319

Table 66., CRBasic Measurement Settling Times, BrFull

Page 319 highlights

Section 8. Operation reversal and excitation reversal results in a 4 ms increase in time for the CR6 to perform the instruction. Figure 86. Input-voltage rise and transient decay b Table 66. CRBasic Measurement Settling Times SettlingTime Argument Resultant Settling Time1 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. • Where possible, run excitation leads and signal leads in separate shields to minimize transients. • When measurement speed is not a prime consideration, additional time can be used to ensure ample settling time. The settling time required can be measured with the CR6. • • In difficult cases, settling error can be measured as described in section Measuring Settling Time (p. 319). Measuring Settling Time Settling time for a particular sensor and cable can be measured with the CR6. Programming a series of measurements with increasing settling times will yield data that indicate at what settling time a further increase results in negligible change in the measured voltage. The programmed settling time at this point indicates the settling time needed for the sensor / cable combination. CRBasic example Measuring Settling Time (p. 320) presents CRBasic code to help determine settling time for a pressure transducer using a high-capacitance semiconductor. The code consists of a series of full-bridge measurements (BrFull()) with increasing settling times. The pressure transducer is placed in 319

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Section 8.
Operation
reversal and excitation reversal results in a 4 ms increase in time for the CR6 to
perform the instruction.
Figure 86. Input-voltage rise and transient decay
b
Table 66.
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.
Where possible, run excitation leads and signal leads in separate shields to
minimize transients.
When measurement speed is not a prime consideration, additional time can be
used to ensure ample settling time.
The settling time required can be
measured with the CR6.
In difficult cases, settling error can be measured as described in section
Measuring Settling Time
(p. 319).
Measuring Settling Time
Settling time for a particular sensor and cable can be measured with the CR6.
Programming a series of measurements with increasing settling times will yield
data that indicate at what settling time a further increase results in negligible
change in the measured voltage.
The programmed settling time at this point
indicates the settling time needed for the sensor / cable combination.
CRBasic example
Measuring Settling Time
(p. 320)
presents CRBasic code to help
determine settling time for a pressure transducer using a high-capacitance
semiconductor.
The code consists of a series of full-bridge measurements
(
BrFull()
) with increasing settling times. The pressure transducer is placed in
319