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

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

SUMMARY

• Conductivity, Temperature, and (optional) Pressure, continuously or at user-programmable intervals (6 seconds to 6 hours).
• RS-232 serial interface (RS-485 optional), internal memory, and external power.
• Expendable anti-foulant devices, unique flow path, and pumping regimen for maximum bio-fouling protection.
• New, high-efficiency pump for longer deployments or shorter sampling intervals.
• Depths to 250 meters (ShallowCAT plastic housing) or 7000 meters (titanium housing).
• Adds to Sea-Bird's field-proven MicroCAT family, with more than 8000 instruments deployed since 1997.

DESCRIPTION

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 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, providing data output 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 time, sound velocity (Chen-Millero), salinity, depth, and/or 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 strain-gauge pressure sensor is available in eight ranges, from 0 - 20 meters to 0 - 7000 meters. Compensation of the temperature influence on pressure offset and scale is performed by the MicroCAT’s CPU.

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

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

• Improved conductivity response – The pump flushes the previously sampled water from the conductivity cell and brings a new water sample quickly into the cell.
• Improved anti-foul protection – Water does not freely flow through the conductivity cell between samples, allowing the anti-foul concentration inside the cell to build up.

COMMUNICATIONS AND INTERFACING

The MicroCAT communicates via standard RS-232 serial interface. Real-time data can be transmitted up to 1600 meters (5200 feet) at 600 baud (power considerations may limit distance), simultaneous with recording. Data can be uploaded at up to 115.2K baud. Firmware upgrades can be downloaded through the communications port, 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:

• Autonomous Sampling – The MicroCAT is pre-programmed to sample, store data in memory, and transmit data. There are two types of autonomous sampling:

• Continuous sampling at the fastest rate possible (0.9 second minimum without pressure), with the pump running continuously
• Interval sampling at  intervals of 6 seconds to 6 hours, with the pump running before each sample.

• Polled Sampling – On command from a computer or satellite, radio, or wire telemetry equipment, the MicroCAT wakes up, runs the pump, samples, and transmits data.
• Serial Line Sync – In response to a pulse on the serial line, the MicroCAT wakes up, runs the pump, samples, stores data in memory, transmits data, and goes to sleep.

SOFTWARE

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

• SeatermV2^© – terminal program for easy communication and data retrieval.
• SBE Data Processing^© – programs for calculation, display, and plotting of conductivity, temperature, pressure (optional), and derived variables such as salinity and sound velocity.

SPECIFICATIONS

Clock Stability: 5 seconds/month

Memory: 8 Mbyte; capacity in excess of 530,000 samples

Input Power: 0.25 Amps at 9 - 24 VDC

Quiescent Current: 30 microAmps *

Communication Current: 4.3 milliAmps *

Acquisition Current: 9.1 milliAmps (excluding pump) *

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

Acquisition Time: 0.9 - 2.7 seconds/sample, dependent on sampling mode and inclusion of pressure sensor

Pump Current: 25 milliAmps

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

Dimensions: in millimeters (inches)

Connector:

ADDITIONAL INFORMATION / LINKS:

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

• Current product manual -- RS-232 and RS-485 versions (older manuals)
• Photo Gallery
• Print version of this specification sheet / brochure
• Application Notes:
  - 2D: Instructions for Care and Cleaning of Conductivity Cells
  - 6: Determination of Sound Velocity from CTD Data
  - 10: Compressibility Compensation of Sea-Bird Conductivity Sensors
  - 14: 1978 Practical Salinity Scale
  - 27Druck: (Druck) Strain Gauge Pressure Sensor Error Sources
  - 42: ITS-90 Temperature Scale
  - 56: Interfacing to RS-485 Sensors
  - 68: Using USB Ports to Communicate with Sea-Bird Instruments
  - 69: Conversion of Pressure to Depth
  - 71: Desiccant Use and Regeneration (drying)
  - 73: Using Instruments with Pressure Sensors at Elevations Above Sea Level
  - 83: Deployment of Moored Instruments
  - 84: Using Instruments with Druck Pressure Sensors in Muddy or Biologically Productive Environments
  - 90: Absolute Salinity and TEOS-10: Sea-Bird's Implementation Plans

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

• Configuration options & accessories:
  - Details for SBE 37-SIP
  - Listing for all products
• Cables
• Mount kits
• Spare parts
• Ads:
  - Moored Salinity? Stop the Flow to Prevent Drift
  - Get More Data per Dollar on your Shallow Moorings

Software -- components of Seasoft V2

• SeatermV2 -- description, download
• SBE Data Processing -- description, download

Links to Other Instruments of Interest

• Other MicroCATs (click here for comparison of features):
  - 37-SI (Serial Interface)
  - 37-SIP-IDO (Serial Interface, integral Pump, & Integrated Dissolved Oxygen)  (membrane-type DO sensor)
  - 37-SIP-ODO (Serial Interface, integral Pump, & integrated Optical Dissolved Oxygen) -- coming soon
  - 37-SM (Serial Interface & Memory)
  - 37-SMP (Serial interface, Memory, & integral Pump)
  - 37-SMP-IDO (Serial interface, Memory, integral Pump, & Integrated Dissolved Oxygen)  (membrane-type DO sensor)
  - 37-SMP-ODO (Serial interface, Memory, integral Pump, & integrated Optical Dissolved Oxygen)
  - 37-IM (Inductive Modem)
  - 37-IMP (Inductive Modem & integral Pump)
  - 37-IMP-IDO (Inductive Modem, integral Pump, & Integrated Dissolved Oxygen)  (membrane-type DO sensor)
  - 37-IMP-ODO (Inductive Modem, integral Pump, & integrated Optical Dissolved Oxygen)
• SBE 16plus V2 (serial interface) and 16plus-IM V2 (Inductive Modem interface) -- moored CTDs that can acquire data from auxiliary sensors

Specifications are subject to change without notice.

Last modified: 29-May-2013

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