Campbell CR6 Series, Руководство оператора

Страница: 416 / 690

Section 8. Operation
416
measurement. The table Analog Voltage Input Ranges and Options
(p. 416)
lists
these input ranges and codes.
An approximate 5% range overhead exists on fixed input voltage ranges. In
other words, over-range on the
±
1000 mV input range occurs at approximately
1050 mV and –1050 mV. The CR6 indicates a measurement over-range by
returning a
NAN
(not a number) for the measurement.
Automatic Range Finding
For signals that do not fluctuate too rapidly, range argument AutoRange allows
the CR6 to automatically choose the voltage range. AutoRange makes two
measurements. The first measurement determines the range to use. It is made
with a first notch frequency ( fN1 ) of 50 kHz on the ±5000 mV range. The
second measurement is made using the range determined from the first and the
same fN1 . Both measurements use the settling time entered in the SettlingTime
parameter. Auto-ranging optimizes resolution but takes longer than a
measurement on a fixed range because of the two-measurement sequences.
An auto-ranged measurement will return NAN ("not a number") if the voltage
exceeds the range picked by the first measurement. To avoid problems with a
signal on the edge of a range, AutoRange selects the next larger range when the
signal exceeds 90% of a range.
Use auto-ranging for a signal that occasionally exceeds a particular range.
AutoRange should not be used for rapidly fluctuating signals, particularly signals
traversing multiple voltage ranges rapidly. The possibility exists that the signal
can change ranges between the internal range check and the actual measurement.
Analog Voltage Input Ranges and Options
Range Code Description
mV5000
1
measures voltages between ±5000 mV
mV1000
1 measures voltages between ±1000 mV
mV200
1 measures voltages between ±200 mV
AutoRange
1
datalogger determines the most suitable
range
1
Append with C to enable common-mode null / open-input detect
(p. 396)
(Example: mV5000C )
Input Limits / Common-Mode Range
Related Topics:
•
Voltage Measurements — Specifications
(p. 102)
• Voltage Measurements — Overview
(p. 72)
•
Voltage Measurements — Details
(p. 415)