CR1000 Manual - Campbell Scientific

2.0
2.1
3.0
10
3.0.1
3.2.1 3
3.3
3.3.1 ‐‐ 8 10
4.0
4.0.1 ‐‐ 10
4.2 ‐‐ 8 10
4.4
3.5.0
3.5.0a
5.0
5.1 ‐‐ 8 10
5.2.1 9
6.0
6.0.1
6.2
6.3
6.4
6.4.1
7.0
7.0.1
7.0
7.0.1
7.2
LOW
7.3
HIGH
7.4
SWITCH‐CLOSURE
7.5
EDGE‐TIMING
7.6
OUTPUT
7.7
OUTPUT
7.8
INPUT
7.9
INPUT
7.10
7.12
8.1
9.0
9.1
9.2
9.3
9.5
10.0
10.1
10.2
10.3
10.4
11.0
11.1
11.2 ‐‐ 8 10
11.3
11.4
12.0
12.1
12.2
13.0
13.1
Section 6. CR1000 Specifications
1.1
CR1000 specifications are valid from ─25° to 50°C in non‐condensing environments unless otherwise specified. Recalibration is recommended every two years. Critical specifications and system
configurations should be confirmed with a Campbell Scientific applications engineer before purchase.
PROGRAM EXECUTION RATE
ms to one day at 10 ms increments
ANALOG INPUTS (SE 1–16, DIFF 1–8)
Eight differential (DIFF) or 16 single‐ended (SE) individually
configured input channels. Channel expansion provided by
optional analog multiplexers.
3.1.0
RANGES and RESOLUTION: With reference to the following table,
basic resolution (Basic Res) is the resolution of a single A/D (p.
447) conversion. A DIFF measurement with input reversal has
better (finer) resolution by twice than Basic Res.
3.1.1 ‐‐ 8 10
DIFF
Basic
Range (mV) 1
±5000
±2500
±250
±25
±7.5
±2.5
Res (μV) 2
667
333
33.3
3.33
1.0
0.33
Res (μV)
1333
667
66.7
6.7
2.0
0.67
1 Range overhead of ≈9% on all ranges guarantees full‐scale
voltage will not cause over‐range.
2 Resolution of DIFF measurements with input reversal.
3.2 ‐‐ 8 10
ANALOG INPUT ACCURACY 3 :
±(0.06% of reading + offset 3 ), 0° to 40°C
±(0.12% of reading + offset 3 ), ‐25° to 50°C
±(0.18% of reading + offset 3 ), ‐55° to 85°C (‐XT only)
Accuracy does not include sensor and measurement noise. Offset
definitions:
Offset = 1.5 x Basic Res + 1.0 µV (for DIFF measurement w/ input
reversal)
Offset = 3 x Basic Res + 2.0 µV (for DIFF measurement w/o input
reversal)
Offset = 3 x Basic Res + 3.0 µV (for SE measurement)
ANALOG MEASUREMENT SPEED:
‐‐‐Total Time 4 ‐‐‐
Integration
Inte‐
Type gration
Code Time
250 250 µs
_60Hz 5 16.67 ms
_50Hz 5 20.00 ms
Settling
Time
450 µs
3 ms
3 ms
SE
with
no
Rev
≈1 ms
≈20 ms
≈25 ms
4 Includes 250 μs for conversion to engineering units.
5 AC line noise filter
DIFF
with
Input
Rev
≈12 ms
≈40 ms
≈50 ms
3.4
INPUT‐NOISE VOLTAGE: For DIFF measurements with input
reversal on ±2.5 mV input range (digital resolution dominates for
higher ranges):
250 μs Integration: 0.34 μV RMS
50/60 Hz Integration: 0.19 μV RMS
INPUT LIMITS: ±5 Vdc
DC COMMON‐MODE REJECTION: >100 dB
NORMAL‐MODE REJECTION: 70 dB @ 60 Hz when using 60 Hz
rejection
INPUT VOLTAGE RANGE W/O MEASUREMENT CORRUPTION: ±8.6
Vdc max.
SUSTAINED‐INPUT VOLTAGE W/O DAMAGE: ±16 Vdc max.
INPUT CURRENT: ±1 nA typical, ±6 nA max. @ 50°C; ±90 nA @ 85°C
INPUT RESISTANCE: 20 GΩ typical
ACCURACY OF BUILT‐IN REFERENCE JUNCTION THERMISTOR (for
thermocouple measurements):
±0.3°C, ‐25° to 50°C
±0.8°C, ‐55° to 85°C (‐XT only)
ANALOG OUTPUTS (VX 1–3)
Three switched voltage outputs sequentially active only during
measurement.
4.0.2
RANGES AND RESOLUTION:
4.1 ‐‐ 8 10
Channel
Range
Resolution
Current
Source
/ Sink
(VX 1–3) ±2.5 Vdc 0.67 mV ±25 mA
ANALOG OUTPUT ACCURACY (VX):
±(0.06% of setting + 0.8 mV, 0° to 40°C
±(0.12% of setting + 0.8 mV, ‐25° to 50°C
±(0.18% of setting + 0.8 mV, ‐55° to 85°C (‐XT only)
VX FREQUENCY SWEEP FUNCTION: Switched outputs provide a
programmable swept frequency, 0 to 2500 mV square waves for
exciting vibrating wire transducers.
PERIOD AVERAGE
Any of the 16 SE analog inputs can be used for period
averaging. Accuracy is ±(0.01% of reading + resolution), where
resolution is 136 ns divided by the specified number of cycles
to be measured.
INPUT AMPLITUDE AND FREQUENCY:
3.5.1 ‐‐ 8 10
Input
Signal
Min
Voltage
Gain
1
10
33
100
Range
Code
mV250
mV25
mV7_5
mV2_5
Peak‐Peak
Min
mV 6
500
10
5
2
Max
V 7
10
2
2
2
Pulse
Width
µs
2.5
10
62
100
Max
Freq
kHz 8
200
50
8
5
6 Signal to be centered around Threshold (see PeriodAvg()
instruction).
7 Signal to be centered around ground.
8 The maximum frequency = 1/(twice minimum pulse width)
for 50% of duty cycle signals.
RATIOMETRIC MEASUREMENTS
MEASUREMENT TYPES: The CR1000 provides ratiometric
resistance measurements using voltage excitation. Three
switched voltage excitation outputs are available for
measurement of four‐ and six‐wire full bridges, and two‐,
three‐, and four‐wire half bridges. Optional excitation polarity
reversal minimizes dc errors.
5.2 ‐‐ 8 10
RATIOMETRIC MEASUREMENT ACCURACY 9,11
Note Important assumptions outlined in footnote 9:
±(0.04% of Voltage Measurement + Offset 12 )
Accuracy specification assumes excitation reversal for
excitation voltages < 1000 mV. Assumption does not include
bridge resistor errors and sensor and measurement noise.
11 Estimated accuracy, ∆X (where X is value returned from
measurement with Multiplier =1, Offset = 0):
BRHalf() Instruction: ∆X = ∆V1 / VX.
BRFull() Instruction: ∆X = 1000 x ∆V1/VX, expressed as mV•V ‐1 .
Note ∆V1 is calculated from the ratiometric measurement
accuracy. See manual section Resistance Measurements (p.
295) for more information.
12 Offset definitions:
Offset = 1.5 x Basic Res + 1.0 µV (for DIFF measurement w/
input reversal)
Offset = 3 x Basic Res + 2.0 µV (for DIFF measurement w/o
input reversal)
Offset = 3 x Basic Res + 3.0 µV (for SE measurement)
Note Excitation reversal reduces offsets by a factor of two.
PULSE COUNTERS (P 1–2)
Two inputs individually selectable for switch closure, high
frequency pulse, or low‐level ac. Independent 24‐bit counters
for each input.
6.1
MAXIMUM COUNTS PER SCAN: 16.7 x 10 6
SWITCH‐CLOSURE MODE:
Minimum Switch Closed Time: 5 ms
Minimum Switch Open Time: 6 ms
Max. Bounce Time: 1 ms open without being counted
HIGH‐FREQUENCY PULSE MODE:
Maximum‐Input Frequency: 250 kHz
Maximum‐Input Voltage: ±20 V
Voltage Thresholds: Count upon transition from below 0.9 V to
above 2.2 V after input filter with 1.2 μs time constant.
LOW‐LEVEL AC MODE: Internal ac coupling removes dc offsets
up to ±0.5 Vdc.
Input Hysteresis: 12 mV RMS @ 1 Hz
Maximum ac‐Input Voltage: ±20 V
Minimum ac‐Input Voltage:
DIGITAL I/O PORTS (C 1‐8)
Eight ports software selectable as binary inputs or control
outputs. Provide on/off, pulse width modulation, edge timing,
subroutine interrupts / wake up, switch‐closure pulse counting,
high‐frequency pulse counting, asynchronous communications
(UARTs), and SDI‐12 communications. SDM communications are
also supported.
7.1
FREQUENCY MODE MAX: