Campbell CR7 Manual do Utilizador descarregar pdf

Extremely Sensitive: 50 nanovolt

resolution at 20 channels per second

throughput.*

Broad Input Range: 16-bit precision

on 8 software-selectable ranges (±5 V

to ±1.5 mV); input ranges up to ±50 V

are possible with the 726 card.

Signal Conditioning Typically Not

Required: Most thermocouples,

RTDs, pressure transducers, humidity

sensors, thermocouple psychrometers,

soil moisture blocks, magnetic pulse

flow transducers, and pulse transduc-

ers are measured directly.

Battery Operated: With the CR7

active 10% of the time (typical

application), fully-charged sealed

rechargeable batteries power the

system for about 5 days. Charging

circuitry is included for solar panels, 12 volt vehicle power, or AC.

Isothermal Design and Transient Protection: Input terminals in

the I/O module are spark gapped to copper bars. The copper bars,

together with aluminum panels between each I/O card, minimize

thermal gradients.

Analog and Digital Control Outputs: Continuous analog outputs

are available for strip-chart recording or proportional control.

Digital outputs can be used with relays to control external devices,

activate alarms, or provide process control.

Expandable: Seven or fourteen card

slot modules are available. Expansion is

also possible with SDMs, multiplexers,

and slaved I/O modules.

Remote Programming and Data

Retrieval: Programs and commands

are entered from the CR7’s keyboard

or from a computer with an appropri-

ate communications link. Data are

stored in internal memory (up to 280K

data points) for transfer to a storage

module, printer, modem, or computer.

Operation in Harsh Environments:

Specifications are valid from -25° to

+50°C. On special order, CR7s are

tested over a -40° to +70°C range. The

ENC 7F or ENC 7XL enclosures

provide protection from humidity and

contaminants.

Internal Processing: Programmable instructions include algebraic,

statistical, and transcendental functions.

Portable: In most field applications, a rugged fiberglass enclosure

houses the system. System weight is ~40 lbs.

Warranty: 3-year warranty covering parts and labor.

*Throughput rate includes similar measurements on adjacent channels, conversion

to engineering units, and storage in Final Memory. Additional processing

decreases given rate. The time between signal conversions on adjacent input chan-

nels is the Input Sample Rate and is given in the Specifications.

Growth Chambers, Greenhouse Monitoring and Control

The CR7 can measure large numbers of distributed air temperature, relative humid-

ity, soil temperature, and solar radiation sensors. Coupled with its ability to monitor

and control HVAC systems, AC power, and water flow, the CR7 is an ideal instru-

ment for controlled-environment applications. The CR7 can be programmed to

maintain measured parameters within preset limits and sound alarms if monitored

systems fail.

Peltier Psychrometers

Psychrometric water potential measurement of soil, plant leaves, or other porous

media requires measurement of the wet-bulb depression of a thermocouple housed

inside a small chamber. The junction is Peltier-cooled below dew point and the wet-

bulb temperature is measured as the water evaporates. Wescor, Inc. (Logan, UT)

markets the CR7 in conjunction with their psychrometers.

Other Applications

• Multi-level meteorologic towers

• Eddy covariance experiments

• Soil temperature profiles

• Lysimeters

CR7 Measurement and Control System

Ultimate Precision in a Rugged, Expandable System

Environmental Applications

Cover photos At left: CR7 Measurement and Control System. From top right:

Automotive

Electric vehicle monitoring, Waterbury, VT;

Process Control

Respiration measurements on woodchips at Silsoe Research Institute, Bedford, England;

Agricultural/Meteorology

USDA/ARS lysimeter installation, Bushland,

TX;

Agricultural Research

NASA CELSS Research Lab, Utah State University, Logan, UT.

A CR7 measures the soil water potential

across a research plot with dozens of thermo-

couple psychrometers. Results are transmitted

via UHF radio to the researcher’s computer.

Green Canyon, UT.

Most applications use a seven card slot system, but larger

applications may require a fourteen card system.

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Resumo do Conteúdo

Página 1 - Environmental Applications

Extremely Sensitive: 50 nanovoltresolution at 20 channels per secondthroughput.*Broad Input Range: 16-bit precisionon 8 software-selectable ranges (±5

Página 2 - Measurement Examples

Industrial ApplicationsVehicle TestThe CR7’s wide operating range (-40° to +70°C, extended), portabil-ity, ruggedness, and expandability make it a use

Página 3 - System Description

System DescriptionThe CR7 features a modular, multiple-processor design that provides precision measurement and control capability in arugged, battery

Página 4 - Data Storage and Transfer

Data Storage and TransferUp to 18,800 (expandable to 280K) raw or processed data points can be stored in the CR7’s memory. Data are trans-ferred to a

Página 5 - Datalogger Support Software

Datalogger Support SoftwareWe offer Windows- and DOS-based software packages that simplify the exchange of data, programs, and commandsbetween the CR7

Página 6 - Specifications

SpecificationsElectrical specifications are valid for over a -25° to +50°C range unless otherwise specified.Analog Inputs(723T or 723 Card specificati

Página 7 - Additional Information

Additional InformationAssurance of QualityCampbell Scientific has produced research-grade dataloggers formore than twenty years. The workmanship and