MicroCAT C-T (P optional) Recorder
SBE 37-SMP (Serial interface, Memory, & integral Pump)

Print version     Current manual - RS-232, RS-485, SDI-12 (older manuals)   Reference Sheet - RS-232, RS-485, SDI-12     Configuration options & accessories

SUMMARY

• Moored Conductivity, Temperature, and (optional) Pressure, at user-programmable 6-sec to 6-hour intervals.
• RS-232, RS-485, or dual SDI-12 and RS-232 interface, internal memory, and internal battery pack (can be powered externally).
• Expendable anti-foulant devices, unique flow path, and pumping regimen for maximum bio-fouling protection.
• Depths to 350 meters (ShallowCAT plastic housing) or 7000 meters (titanium housing).
• Sea-Bird's field-proven MicroCAT family, with more than 10,000 instruments deployed since 1997.
• Five-year limited warranty.

DESCRIPTION

The SBE 37-SMP MicroCAT is a high-accuracy conductivity and temperature (pressure optional) recorder with Serial interface, internal battery, non-volatile Memory, and integral Pump. The MicroCAT is designed for moorings or other long-duration, fixed-site deployments. Constructed of non-corroding materials to ensure long life with minimum maintenance, it is rated for operation to 350 meters (plastic ShallowCAT housing) or 7000 meters, or pressure sensor full-scale range.

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 includes Conductivity, Temperature, (optional) Pressure, and time; salinity and sound velocity can also be output.

SENSORS

The MicroCAT retains the temperature and conductivity sensors used in our time-proven SeaCAT and SeaCATplus. Electrical isolation of the conductivity electronics eliminates any possibility of ground-loop noise. The 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, to a maximum depth of 7000 meters. Compensation of the temperature influence on pressure offset and scale is performed by the MicroCAT’s CPU.

The integral pump runs for 1 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 maintain saturation.

COMMUNICATIONS AND INTERFACING

The MicroCAT communicates via one of the following interfaces:

• RS-232 – Real-time data can be transmitted up to 1600 meters at 600 baud, simultaneous with recording. Data can be uploaded at up to 115.2K baud. The user can upgrade firmware through the external connector, without opening the housing.

• RS-485 – Multiple MicroCATs can share a common 2-wire cable, minimizing cable complexity for C-T chains.

• RS-232 / SDI-12 – Dual interface allows for setup and data upload via RS-232 using the full set of commands, while a more limited set of commands can be sent via SDI-12 to make small setup changes in the field and to poll for data. User-selectable output variables for this interface, designed for coastal deployments, includes specific conductivity.

User-selectable operating modes include:

• Autonomous – At pre-programmed 6-sec to 6-hour intervals, the MicroCAT wakes up, runs the pump, takes 1 sample, stores data in memory, and goes to sleep.
• Polled – 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, takes 1 sample, stores data in memory, and goes to sleep.

SOFTWARE

The MicroCAT is supplied with a powerful Windows 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, sound velocity, and density.

DATA STORAGE AND BATTERY ENDURANCE

Temperature and conductivity are stored 6 bytes/sample, time 4 bytes/sample, and optional pressure 5 bytes/sample; memory capacity exceeds 530,000 samples. The MicroCAT is powered by a 7.8 Amp-hour (nominal) battery pack with twelve AA lithium cells (Saft LS14500) which, when removed from the MicroCAT, can be shipped via commercial aircraft. The pack provides sufficient internal battery capacity for more than 380,000 samples for a typical sampling scheme. *

SPECIFICATIONS

Clock Stability: 5 sec/month

Quiescent Current: 30 microAmps *

Sampling and Communication Current: *
Communication 4.3 milliAmps
Sampling (excluding pump)
     9.1 milliAmps if transmitting real-time data;
     7.9 milliAmps if not transmitting real-time data

* Power consumption / battery endurance values are for RS-232 interface; for other interfaces, see corresponding manual.

Pump Current: 0.025 Amp-sec/sample

Acquisition Time: 1.9 - 2.9 sec/sample, dependent on sampling mode and inclusion of pressure sensor

Power Supply: 7.8 Amp-hour (nominal) battery pack

Optional External Power: 0.25 Amps at 9 - 24 VDC

Housing, Depth Rating, and Weight:

Dimensions in millimeters (inches)

Connector:

ADDITIONAL INFORMATION / LINKS:

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

• Current product manual -- RS-232, RS-485, and SDI-12 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
  - 90: Absolute Salinity and TEOS-10: Sea-Bird's Implementation Plans
• Shipment of lithium batteries used to power MicroCAT
• Sea-Bird webinar -- Introduction to Sea-Bird, Long-Term Deployments with Moored CTDs, and CTD Profilers

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

• Configuration options & accessories:
  - Details for SBE 37-SMP
  - 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

• Deployment Endurance Calculator -- description, download
• SeatermV2 -- description, download
• SBE Data Processing -- description, download

Links to Other Instruments of Interest

• Other MicroCATs (compare features):
  - 37-SM (Serial interface & Memory)
  - 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-SI (Serial Interface)
  - 37-SIP (Serial Interface & integral Pump)
  - 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-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.

Sea-Bird Home     Phone: (+1) 425-643-9866     E-mail: seabird@seabird.com