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MicroCAT C-T (P optional) Sensor
SBE 37-SIP
(S
erial Interface & integral Pump)

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Print version     Current manual - RS-232 or RS-485 (for older manuals, click here)    Reference Sheet - RS-232 or RS-485     Configuration options & accessories

DESCRIPTION

Intended for deployment in orientation shown (connector at bottom) for proper operation
SBE 37-SIP with standard titanium housing
Standard titanium housing; optional plastic (ShallowCAT) housing also available

The SBE 37-SIP MicroCAT is a high-accuracy conductivity and temperature (pressure optional) sensor with Serial Interface and integral Pump, which includes a non-volatile FLASH memory. Externally powered, it is intended for moorings or other long-duration, fixed-site deployments. Constructed of titanium and other non-corroding materials to ensure long life with minimum maintenance, the MicroCAT's depth capability is 7000 meters (23,000 feet); it is also available with an optional 250-meter plastic ShallowCAT housing.

Calibration coefficients are stored in EEPROM, allowing the MicroCAT to output data in ASCII engineering units (decimal or XML format); raw output is also available. The data always includes Conductivity, Temperature, and Pressure (if optional pressure sensor is installed); users can choose to add any combination of time, sound velocity (Chen-Millero), salinity, depth, and density.

The MicroCAT retains the temperature and conductivity sensors used in our time-proven SEACAT and SEACAT plus products. Electrical isolation of the conductivity electronics eliminates any possibility of ground-loop noise. The MicroCAT’s unique internal-field conductivity cell permits the use of expendable anti-foulant devices. The aged and pressure-protected thermistor has a long history of exceptional accuracy and stability.

The optional Druck pressure sensor has a superior design that is entirely different from conventional ‘silicon’ types in which the deflection of a metallic diaphragm is detected by epoxy-bonded silicon strain gauges. The Druck sensor employs a micro-machined silicon diaphragm into which the strain elements are implanted using semiconductor fabrication techniques. Unlike metal diaphragms, silicon’s crystal structure is perfectly elastic, so the sensor is essentially free of pressure hysteresis. Compensation of the temperature influence on pressure offset and scale is performed by the MicroCAT’s CPU.

SENSOR INTERFACE ELECTRONICS

Temperature is acquired by applying an AC excitation to a hermetically sealed VISHAY reference resistor and an ultra-stable aged thermistor (drift rate typically less than 0.002 °C per year). The ratio of thermistor resistance to reference resistance is determined by a 24-bit A/D converter; this A/D also processes the pressure sensor signal. Conductivity is acquired using an ultra-precision Wien-Bridge oscillator.

PUMP

The integral pump typically runs for 1.0 second each time the MicroCAT samples, providing the following advantages:

COMMUNICATIONS AND INTERFACING

The MicroCAT communicates directly with a computer via a standard serial interface. Real-time data can be transmitted at distances of up to 1600 meters (5200 feet) at 600 baud (power considerations may limit the distance), simultaneous with recording. Data can be uploaded at up to 115.2K baud. Firmware upgrades can be downloaded through the communications port by the user, without opening the instrument. An optional RS-485 interface allows multiple MicroCATs to share a common 4-wire cable (power, common, data +, data -), minimizing cable complexity for C-T chains.

User-selectable operating modes include:

SOFTWARE

The MicroCAT is supplied with a powerful Windows 2000/XP software package, SEASOFT© V2, which includes:

SPECIFICATIONS

  Measurement
Range
Initial
Accuracy
Typical
Stability
Resolution
Conductivity 0 to 7 S/m
(0 to 70 mS/cm)
0.0003 S/m 
(0.003 mS/cm)
0.0003 S/m
(0.003 mS/cm)
per month
0.00001 S/m
(0.0001 mS/cm)
Temperature
 (°C)
-5 to 35 0.002 0.0002 per month 0.0001
Optional Pressure 20 / 100 / 350 / 600 / 1000 / 2000 / 3500 / 7000 m
(Expressed in meters of deployment depth capability)
0.1% of full scale range 0.05% of full scale range per year 0.002% of full scale range
         

Clock Stability: 5 seconds/month

Input Power: 0.5 Amps at 8.5 - 24 VDC

Quiescent Current: 30 microamps *

Communication Current: 4.3 milliamps *

Acquisition Current: 15 milliamps (excluding pump) *

* Power consumption values are for standard RS-232 interface; for optional RS-485 interface, see RS-485 manual.

Acquisition Time: 1.0 - 2.6 seconds/sample, dependent on sampling mode and inclusion of pressure sensor

Pump Current: 260 milliamps

Housing, Depth Rating, and Weight (without pressure sensor or clamps):

  Housing Material Depth Rating Weight
Standard Titanium 7000 m (23,000 feet) 4.2 kg (9.2 lbs) in air
2.8 kg (6.2 lbs) in water
Optional ShallowCAT Plastic 250 m (820 ft) 3.1 kg (6.9 lbs) in air
1.7 kg (3.8 lbs) in water
       

Dimensions: in millimeters (inches)

Connector:

ADDITIONAL INFORMATION / LINKS:

Documentation -- manual, photos, technical papers, application notes, etc.

Sales Information -- options, accessories, cables, mount kits, spares, etc.

Software -- components of Seasoft V2

Links to Other Instruments of Interest

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Specifications are subject to change without notice.

Last modified: 04-Mar-2011

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