SBE SeaCAT 21 User manual

SBE 21 SeaCAT
Thermosalinograph
Conductivity and Temperature Recorder
with RS-232 Interface
User’s Manual
Sea-Bird Electronics, Inc.
13431 NE 20th Street
Bellevue, Washington 98005 USA Manual Version #027, 02/21/13
Telephone: [phone] SBE 21 Firmware 5.0a and later
Fax: [phone] Interface Box Firmware 3.1b and later
E-mail: [e-mail] Seasave V7 Version 7.22.4 and later
Website: www.seabird.com SBE Data Processing Version 7.22.4 and later

2
Limited Liability Statement
Extreme care should be exercised when using or servicing this equipment. It should be used or serviced
only by personnel with knowledge of and training in the use and maintenance of oceanographic
electronic equipment.
SEA-BIRD ELECTRONICS, INC. disclaims all product liability risks arising from the use or servicing
of this system. SEA-BIRD ELECTRONICS, INC. has no way of controlling the use of this equipment
or of choosing the personnel to operate it, and therefore cannot take steps to comply with laws
pertaining to product liability, including laws which impose a duty to warn the user of any dangers
involved in operating this equipment. Therefore, acceptance of this system by the customer shall be
conclusively deemed to include a covenant by the customer to defend, indemnify, and hold SEA-BIRD
ELECTRONICS, INC. harmless from all product liability claims arising from the use or servicing of
this system.

Manual revision 027 Declaration of Conformity SBE 21
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Declaration of Conformity

Manual revision 027 Table of Contents SBE 21
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Table of Contents
Limited Liability Statement ................................................................ 2
Declaration of Conformity .................................................................. 3
Table of Contents ................................................................................. 4
Section 1: Introduction ........................................................................ 6
About this Manual .............................................................................................6
Unpacking SBE 21.............................................................................................7
Section 2: Description of SBE 21 ........................................................ 8
System Description ............................................................................................8
Specifications...................................................................................................10
Dimensions and Bulkhead Connectors ............................................................11
Data I/O ...........................................................................................................12
Data Storage.....................................................................................................12
Remote Temperature Sensor (optional) ...........................................................12
Section 3: Installing System .............................................................. 13
Installing Software ...........................................................................................13
System Schematic and Installation Guidelines ................................................14
Mechanical Installation....................................................................................16
Electrical Installation .......................................................................................17
Section 4: Setting Up SBE 21 ............................................................ 19
Setting Communications Parameters in Interface Box.....................................19
Power and Communications Test and SBE 21 Setup in Seaterm ....................19
Command Descriptions....................................................................................24
Checking SBE 21 Configuration (.xmlcon or .con) File in Seasave ................39
Data Formats....................................................................................................41
Notes on SBE 38 Remote Temperature Data Format ...............................42
Section 5: Setting Up NMEA Interface............................................ 43
NMEA Operating Modes .................................................................................43
Setting Up and Testing NMEA........................................................................44
Troubleshooting NMEA Interface ...................................................................46
Setting Up SBE 21 Configuration (.xmlcon or .con) File................................46
Section 6: Operating System ............................................................. 47
Acquiring Real-Time Data with Seasave.........................................................47
Uploading SBE 21 Data from Memory ...........................................................50
Processing Data................................................................................................53
Section 7: Routine Maintenance and Calibration ........................... 55
Corrosion Precautions......................................................................................55
Removing Sensor/Electronics Module from SBE 21 Water Jacket .................55
Cleaning and Storage .......................................................................................56
Sensor Calibration............................................................................................57
Section 8: Troubleshooting................................................................ 58
Problem 1: Unable to Communicate with Interface Box .................................58
Problem 2: Unable to Communicate with SBE 21...........................................58
Problem 3: Unable to View Data in Seasave
(Real-Time Data Acquisition program) ...........................................................59
Problem 4: Scan Length Error in SBE Data Processing ..................................59
Problem 5: No Data Recorded .........................................................................59
Problem 6: Nonsense or Unreasonable Data....................................................59
Problem 5: Salinity Lower than Expected .......................................................60
Problem 6: Program Corrupted ........................................................................60

Manual revision 027 Table of Contents SBE 21
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Glossary .............................................................................................. 61
Appendix I: Functional Description................................................. 62
Sensors .............................................................................................................62
Sensor Interface ...............................................................................................62
Real-Time Clock..............................................................................................62
Power ...............................................................................................................62
Appendix II: Electronics Disassembly/Reassembly ........................ 63
Appendix III: Command Summary ................................................. 65
Appendix IV: AF24173 Anti-Foulant Device .................................. 67
Appendix V: Replacement Parts ...................................................... 71
Appendix VI: Manual Revision History .......................................... 73
Index.................................................................................................... 75

Manual revision 027 Section 1: Introduction SBE 21
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Section 1: Introduction
This section includes contact information and photos of a standard
SBE 21 shipment.
About this Manual
This manual is to be used with the SBE 21 SeaCAT Thermosalinograph
Conductivity and Temperature Recorder. It is organized to guide the user from
installation through operation and data collection. We have included detailed
specifications, command descriptions, maintenance and calibration
information, and helpful notes throughout the manual.
Sea-Bird welcomes suggestions for new features and enhancements of our
products and/or documentation. Please contact us with any comments or
suggestions ([email protected] or 425-643-9866). Our business hours are
Monday through Friday, 0800 to 1700 Pacific Standard Time (1600 to 0100
Universal Time) in winter and 0800 to 1700 Pacific Daylight Time (1500 to
0000 Universal Time) the rest of the year.

Manual revision 027 Section 1: Introduction SBE 21
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Unpacking SBE 21
Shown below is a typical SBE 21 shipment.
Cell cleaning solution
(Triton X-100)
SBE 21
Software, and Electronic Copies of
Software Manuals and User Manual
I/O cable
(SBE 21 to Interface Box)
AC power cable for
Interface Box
Grounding cable
(from SBE 21)
I/O cable
(Interface Box to computer)
Jackscrew kit
4-pin RMG-4FS pigtail with
locking sleeve (from SBE 21
to Interface Box)
NMEA Interface test cable
(Interface Box to NMEA device
simulation computer)
4-pin
MS connector
assembly
(for SEACAT data
I/O connector on
Interface Box)
50369 5-pin
MS connector
assembly
(for NMEA Input
connector on
Interface Box)
PN 90488 –
SeaCAT/Sealogger
RS-232 and Navigation
Interface Box

Manual revision 027 Section 2: Description of SBE 21 SBE 21
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Section 2: Description of SBE 21
This section describes the functions and features of the SBE 21,
including specifications and dimensions.
System Description
The SBE 21 SeaCAT Thermosalinograph is an externally powered, high-
accuracy, conductivity and temperature recorder, designed for shipboard
determination of sea surface (pumped-water) conductivity and temperature.
Data is simultaneously transmitted to a computer’s serial port and stored in
64 Mb FLASH RAM memory, allowing both real-time data acquisition and
independent data logging. An internal lithium back-up battery in the SBE 21
supports the real-time clock when the main power supply is off.
The SBE 21 is connected by cable to PN 90488 - SeaCAT/Sealogger
RS-232 and Navigation Interface Box. The Interface Box is AC-powered,
provides isolated DC power and an optically-isolated RS-232 data interface for
the SBE 21, and provides power and a NMEA 0183 receiver for a NMEA
device (not supplied by Sea-Bird). The Interface Box appends NMEA
information to the SBE 21 data stream.
The platinum-electrode glass conductivity cell’s unique internal-field
geometry eliminates proximity effects. This feature is critically important in
thermosalinographs, where the cell must operate in a water jacket’s confined
volume. The internal-field cell also allows the use of expendable AF24173
Anti-Foulant Devices (supplied).
For corrosion resistance, only plastic, titanium, and the glass/platinum
conductivity cell are exposed to seawater. Valves control seawater circulation
and fresh water flushing. The sensor assembly is easily removed for cleaning
and calibration.
The PVC base or back plate may be drilled for mounting to the ship. Seawater
connections (for normal use) and fresh water connections (for cleaning) are
PVC pipes with 1-inch (25.4 mm) U.S. standard NPT threads. Mating female
fittings are provided, and can easily be adapted to locally available pipe sizes.
Communication with the SBE 21 is over an internal, 3-wire, RS-232C link,
providing real-time data transmission. Commands can be sent to the SBE 21 to
provide status display, data acquisition setup, data retrieval, and diagnostic
tests. Output format is raw, hexadecimal data. The SBE 21 samples using one
of the following user-programmable schemes:
•Continuously at 4 Hz: At pre-programmed 3- to 600-second intervals,
the SBE 21 averages all the data from within the sampling interval, stores
the average in memory, and sends the average to the computer (through
the Interface Box).
•At pre-programmed intervals: At pre-programmed 3- to 600-second
intervals, the SBE 21 takes one sample, stores the sample in memory, and
sends the sample data to the computer (through the Interface Box).
A standard SBE 21 can record the output of an optional remote temperature
sensor (SBE 38), allowing for the measurement of sea surface temperature
with minimum thermal contamination from the ship’s hull. A stainless steel
and plastic in-line pipe mount is available for safe below-waterline installation
of the remote temperature sensor (see Section 3: Installing System).
Note:
Seasave 7.18 or later also
supports acquisition of data from a
NMEA device connected directly
to the computer (instead of the
interface box).

Manual revision 027 Section 2: Description of SBE 21 SBE 21
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A standard SBE 21 is supplied with:
•Bulkhead connectors:
one 4-pin I/O connector
one 6-pin connector for A/D inputs (four single-ended or
two differential channels – customer selects desired configuration at
time of purchase)
one 4-pin connector for remote temperature sensor
one 1-pin connector for ground to ship’s hull
•64 Mbyte FLASH RAM memory
•Anti-foulant device attachments and expendable AF24173 Anti-Foulant
Devices on each end of the conductivity cell.
•PN 90488 – SeaCAT/Sealogger RS-232 and Navigation Interface Box,
providing power to the SBE 21, an optically isolated RS-232 interface, a
NMEA 0183 input port for NMEA data, and power for a NMEA device.
SBE 21 options include:
•Remote temperature sensor (SBE 38) and mounting kit
•Auxiliary A/D sensors (mounts not supplied)
Future upgrades and enhancements to the SBE 21 firmware can be easily
installed in the field through a computer serial port and the I/O connector on
the SBE 21, without the need to return the SBE 21 to Sea-Bird.
The SBE 21 is supplied with a powerful Windows software package,
Seasoft©V2, which includes:
•Seaterm –terminal program for easy communication and
data retrieval.
•Seasave V7 –program for acquiring, converting, and displaying real-time
or archived raw data.
•SBE Data Processing - program for calculation and plotting of
conductivity, temperature, data from auxiliary sensors, and derived
variables such as salinity and sound velocity.
Notes:
•Help files provide detailed
information on the software.
•Separate software manuals contain
detailed information on Seasave V7
and SBE Data Processing.
•Sea-Bird also supplies an older
version of Seasave, Seasave-
Win32. However, all Seasave
instructions in this manual are
written for Seasave V7. See
Seasave-Win32’s manual and/or
Help files if you prefer to use the
older software.
•Sea-Bird supplies the current
version of our software when you
purchase an instrument. As software
revisions occur, we post the revised
software on our FTP site. See our
website (www.seabird.com) for the
latest software version number, a
description of the software changes,
and instructions for downloading the
software from the FTP site.

Manual revision 027 Section 2: Description of SBE 21 SBE 21
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Specifications
Conductivity
(S/m)
Primary
Temperature
(°C)
SBE 38
Secondary
Temperature
(°C)
Measurement
Range 0 to 7 -5 to +35 -5 to +35
Initial Accuracy 0.001 0.01 0.001
Resolution 0.0001 0.001 0.0003
Calibration
(measurement outside
these ranges may be
at slightly reduced
accuracy due to
extrapolation errors)
0 to 7; physical
calibration over
the range 2.6 to
6 S/m, plus zero
conductivity (air)
+1 to +32 -1 to +32
Memory 64 Mbyte non-volatile FLASH memory
Data Storage
Recorded Parameter Bytes/sample
temperature and conductivity 6 (3 each)
each external voltage 2
SBE 38 remote temperature 3
Real-Time Clock 32,768 Hz TCXO accurate to ±1 minute/year
Sample Rate 1 sample / 3 seconds to 1 sample / 600 seconds
Sample rate is incremented in 1-second steps
Materials PVC housing, water jacket, piping, and valves;
titanium end cap
Recommended
Flow Rate 1 liter/second (15.8 gallons/minute)
Auxiliary
Voltage Sensors
Auxiliary power out: up to 500 mA at 10.5 - 11 VDC
A/D resolution: 12 bits
Input range: 0 - 5 VDC
Maximum
Safe Operating
Pressure
34.5 decibars (50 psi)
Input Power
SeaCAT/Sealogger RS-232 and Navigation
Interface Box is included with standard SBE 21
order. If testing SBE 21 without Interface Box,
provide 9-14 VDC power.
Weight 41 kg (90 lbs)

Manual revision 027 Section 2: Description of SBE 21 SBE 21
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Dimensions and Bulkhead Connectors
Dimensions in millimeters (inches)

Manual revision 027 Section 2: Description of SBE 21 SBE 21
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Data I/O
The SBE 21 receives set-up instructions and outputs diagnostic information or
previously recorded data via a three-wire RS-232C link, and is factory-
configured for 4800 baud, 7 data bits, 1 stop bit, and even parity. SBE 21
RS-232 levels are directly compatible with standard serial interface cards (IBM
Asynchronous Communications Adapter or equal). The communications baud
rate can be changed using Baud= (see Command Descriptions in Section 4:
Setting Up SBE 21).
Data Storage
The SBE 21 has a 64 Mbyte FLASH memory. See Specifications for storage
space required for each parameter.
Remote Temperature Sensor (optional)
The SBE 21 can record the output of an external SBE 38 temperature sensor.
Often, the SBE 21 is mounted in the interior of the vessel. In this configuration
the recorded conductivity is correct, but the water temperature changed as it
passed through the plumbing system. The SBE 38 can be placed in a location
that provides more accurate measurement of the sea surface water temperature.
The ideal location for the SBE 38 is at the seawater intake (before the
pump) near the bow of the ship. This minimizes contamination of the
surface temperature measurement by the ship’s own thermal mass.
To compute salinity, always use the data from the temperature sensor on
the SBE 21, not from the SBE 38. Conductivity has a strong thermal
coefficient; therefore, it is critical to know the temperature of the water when
the conductivity sensor samples it in order to compute salinity correctly. On a
typical installation, there may be 20 to 30 meters of plumbing between the
SBE 38 and the SBE 21. As the water flows through the pipes it changes
temperature dramatically, making the data from the SBE 38 an inaccurate
representation of the temperature when the water reaches the conductivity
sensor. Use the SBE 38 only to report surface temperature, and to calculate
density and sound velocity (density and sound velocity are a function of
salinity and temperature).
Note that the SBE 38 can be added to the system at any time, and does not
need to be part of the original order for the SBE 21. No modifications to the
SBE 21 are required to integrate the SBE 38, other than programming the
SBE 21 to accept the sensor signal and updating the configuration (.xmlcon or
.con) file.
Example 1: no auxiliary sensors
T & C = 6 bytes/sample
Storage space ≈64,000,000 / 6 ≈10,666,666 samples
Example 2: 4 external voltages, SBE 38 remote temperature sensor
T & C = 6 bytes/sample
External voltages = 2 bytes/sample x 4 voltages = 8 bytes/sample
SBE 38 = 3 bytes/sample
Storage space ≈64,000,000 / (6 + 8 + 3) ≈3,764,705 samples
Note:
If FLASH memory is filled to
capacity, sampling and transmission
of real-time data continue, but
excess data is not saved in memory.
The SBE 21 will not overwrite data
stored in memory.
Note:
Sea-Bird software (Seasave real-
time data acquisition and SBE Data
Processing’s Data Conversion and
Derive modules) uses the data from
the SBE 21’s temperature sensor
to calculate salinity, and then
uses that salinity with the
temperature from the remote
temperature sensor to calculate
density and sound velocity.

Manual revision 027 Section 3: Installing System SBE 21
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Section 3: Installing System
This section provides instructions for:
•Installing software
•Mounting and wiring the SBE 21 and Interface Box, including system
schematic and installation guidelines, mechanical installation, and
electrical installation
Installing Software
Seasoft V2 was designed to work with a PC running Windows XP service
pack 2 or later, Windows Vista, or Windows 7.
If not already installed, install Sea-Bird software programs on your computer
using the supplied software CD.
1. Insert the CD in your CD drive.
2. Install software: Double click on SeasoftV2.exe. Follow the dialog box
directions to install the software. The installation program allows you to
install the desired components. Install all the components, or just install
Seaterm (terminal program), Seasave V7 (real-time data acquisition), and
SBE Data Processing (data processing).
The default location for the software is c:\Program Files\Sea-Bird. Within that
folder is a sub-directory for each component.
Notes:
•Help files provide detailed
information on the software.
Separate software manuals on the
CD-ROM contain detailed
information on Seasave V7 and
SBE Data Processing.
•Sea-Bird also supplies an older
version of Seasave, Seasave-
Win32. However, all Seasave
instructions in this manual are
written for Seasave V7. See
Seasave-Win32’s manual and/or
Help files if you prefer to use the
older software.
•It is possible to use the SBE 21
without the Seaterm terminal
program by sending direct
commands from a dumb terminal or
terminal emulator, such as Windows
HyperTerminal.
•Sea-Bird supplies the current
version of our software when you
purchase an instrument. As software
revisions occur, we post the revised
software on our FTP site. See our
website (www.seabird.com) for the
latest software version number, a
description of the software changes,
and instructions for downloading the
software from the FTP site.

Manual revision 027 Section 3: Installing System SBE 21
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System Schematic and Installation Guidelines
Sea-Bird does not provide detailed installation instructions for the SBE 21 and
remote temperature sensor, given the unique nature of every ship and type of
installation. The installation of the SBE 21 should be done by qualified
shipfitters, with the oversight of a competent ship designer or naval architect.
Valves are show in normal operating position.
Valves are open when handle is horizontal,
closed when handle is vertical.
Notes:
•The SeaCAT/Sealogger RS-232 and
Navigation Interface Box is included
with a standard SBE 21 order. If testing
the SBE 21 without the Interface Box,
provide 9-14 VDC power.
•Seasave 7.18 or later also supports
acquisition of data from a NMEA device
connected directly to the computer
(instead of the Interface Box).

Manual revision 027 Section 3: Installing System SBE 21
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Consider the following:
•The SBE 21 can be mounted anywhere it will fit that is accessible for
maintenance and cleaning. For safety, mount the SBE 21 above the
water line.
If the remote temperature sensor is not used, mount the SBE 21 as
close to the seawater intake as possible to avoid thermal
contamination of long plumbing runs. Thermal contamination will not
affect salinity accuracy, but the SBE 21 will report the temperature of
the water when it reaches the instrument.
If the remote temperature sensor is used, the SBE 21 can be mounted
in the ship’s lab or other convenient location.
The maximum recommended cable length from the SBE 21 to the
Interface Box is 100 meters.
•Sea-Bird does not recommend or supply a pump. The pump should be
able to provide 1 liter/second (15.8 gallons/minute) flow. Pressure at the
SBE 21 is limited to 34.5 decibars (50 psi).
•Bubbles in the plumbing of a flow-through system are a common problem
and will cause noisy salinity data. To minimize bubbles:
Place the pump below the water line to push rather than pull
the water.
Locate the SBE 21’s hull intake as deep as possible, as far as possible
from bubble sources (bow wake, propeller, etc.)
•Depending on the chosen design of a permanent seawater supply
(including pump, intake fitting, pipes, etc.), a de-bubbling device may be
needed to separate bubbles from the water before it enters the SBE 21.
Note that a de-bubbler may cause additional temperature errors for the
SBE 21’s primary temperature sensor; salinity accuracy (and accuracy of
an optional remote temperature sensor) is not affected. Not all ships
require de-bubblers, but many do for best quality salinity data. Large
single point salinity spikes can be removed with the Wild Edit module in
SBE Data Processing.
•Route cabling as cleanly as possible, avoiding sources of noise. Electric
motors are a particular problem. Avoid routing the cable next to
generators and air conditioners. Cables longer than 3 meters should be
installed inside an earthed metal conduit by a qualified electrician. This
minimizes the potential for external signals to disrupt communication and
ensures that high voltage lines (such as the sea cable) are sufficiently
protected. Cables shorter than 3 meters can be used without shielding
when installing or bench testing the instrument.
•If practical, mount the optional SBE 38 remote temperature sensor outside
the hull. However, the remote temperature sensor is usually mounted in
the remote sensor mount kit, which has 1-inch pipe threads on each end;
plumb the mount kit into your seawater system. Install the SBE 38 as
close to the seawater intake as possible (before the pump), near the bow of
the ship. Since the installation is below the water line, consult with your
ship’s engineer / naval architect / shipyard regarding the actual
installation. Sea-Bird cannot offer advice in this matter as each ship is
different and plumbing regulations vary.
•The SBE 21 can record a maximum of four auxiliary voltages from
auxiliary sensors. However, Sea-Bird has not developed methods for the
mechanical integration of these auxiliary sensors with the SBE 21.
When integrating auxiliary sensors with the SBE 21, consider the
following issues:
Install the sensors in a flow-through chamber that receives the
outflow from the SBE 21.
Design the flow-through chamber so sensors can be removed and
replaced for service and calibration.
Protect auxiliary sensors from bio-fouling.

Manual revision 027 Section 3: Installing System SBE 21
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Mechanical Installation
1. A new SBE 21 is shipped with AF24173 Anti-Foulant Devices
pre-installed. Verify that the Devices are installed (see Removing
Sensor/Electronics Module from SBE 21 Water Jacket in Section 7:
Routine Maintenance and Calibration and Appendix IV: AF24173
Anti-Foulant Device).
2. Mount the SBE 21 at the desired location:
•Orient the SBE 21 with the bulkhead connectors at the top.
•Provide minimum top clearance of 559 mm (22 inches) for removal
of the sensor/electronics module from the water jacket.
•Drill the PVC base or back plate, and mount to the ship using
machine bolts.
3. Install the piping connections to the SBE 21. The connectors are
1-inch (25.4 mm) National (USA) threads. Female mating fittings suitable
for connecting to PVC plastic pipe with glue are provided; they may be
modified for use with existing piping.
A. Connect the Out fitting to the shipboard drain or to the low pressure
side of salt water supply.
B. Connect the Fresh Water In fitting to the shipboard fresh
water supply.
C. Connect the Salt Water In fitting to the shipboard sea surface water
intake line.
D. Connect the Drain fitting to shipboard drain.
4. Set the valves, as described in the following table. The valve is open when
the handle is horizontal and closed when the handle is vertical.
Valve Normal
Use
Fresh
Water
Flushing
Storage, Cleaning, or
Removal of
Sensor/Electronics Module
Out
Open
Open
Closed
Fresh Water In
Closed
Open
Closed
Salt Water In
Open
Closed
Closed
Drain
Closed
Closed
Closed
Valves shown in Normal Use position
Base
Backplate

Manual revision 027 Section 3: Installing System SBE 21
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Electrical Installation
Connecting SBE 21 to Interface Box
1. Locate the Interface Box near the computer.
•If the distance between the SBE 21 and Interface Box is longer than
the provided 10 meter I/O cable, cut the cable and splice it into the
ship’s cable. The ship’s cable should have 3 conductors, preferably
with at least 2 of the conductors shielded (RS-232 TX and RX) if
engine ignition noise or other EM interference might be encountered.
See drawing number 31063 for cable wiring details.
2. Connect the I/O cable to the SBE 21:
A. By hand, unscrew the locking sleeve from the SBE 21’s I/O
(4-pin) connector. If you must use a wrench or pliers, be careful not
to loosen the I/O connector instead of the locking sleeve.
B. Remove the dummy plug from the SBE 21’s I/O connector by pulling
the plug firmly away from the connector.
C. Lightly lubricate the inside of the 4-pin cable connector with silicone
grease (DC-4 or equivalent).
D. Install the 4-pin cable connector on the SBE 21, aligning the raised
bump on the side of the connector with the large pin on the SBE 21’s
bulkhead connector. Remove any trapped air by burping or gently
squeezing the connector near the top and moving your fingers toward
the end cap.
E. Place the locking sleeve over the cable connector. Tighten the locking
sleeve finger tight only. Do not overtighten the locking sleeve, and
do not use a wrench or pliers.
3. Connect the MS-style metal shell connector on the I/O cable to SBE 21 on
the Interface Box.
Connecting SBE 21 to Ground and to Auxiliary Sensors
1. Connect the SBE 21’s 1-pin ground connector to ship’s ground.
2. (optional) Install the cable between the SBE 21 and optional SBE 38
Remote Temperature Sensor.
3. (optional) Install the cable(s) for optional auxiliary voltage sensors.
Note:
Follow the procedure in Steps 2A
through 2E for proper installation of
all cables with similar connectors.
CAUTION:
Do not use WD-40 or other
petroleum-based lubricants, as they
will damage the connector.
Note:
The Interface Box is included with a
standard SBE 21 order. If testing the
SBE 21 without the Interface Box,
provide 9-14 VDC power.

Manual revision 027 Section 3: Installing System SBE 21
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Connecting Interface Box
1. Connect Serial on the Interface Box to the computer using the DB-9S to
DB-9P cable.
2. Connect the Interface Box AC Input to a standard, 3-prong, grounded,
AC outlet, using the UL/IEC-approved power cord (AC voltage between
85-270 VAC).
3. (optional) Connect a NMEA device to NMEA on the Interface Box with
the 5-pin MS connector (MS3106A14S-5P). The connector pin
designations are:
Interface Box
Function
Pin A
Optional power return
Pin B
NMEA A(signal)
Pin C
NMEA B(signal return)
Pin D
No connection
Pin E
Optional +12 DC power out, up to 2 amps

Manual revision 027 Section 4: Setting Up SBE 21 SBE 21
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Section 4: Setting Up SBE 21
This section describes:
•Setting communications parameters in the Interface Box
•Testing power and communications and setting up the SBE 21 in Seaterm
•Command descriptions
•Setting up the configuration (.xmlcon or .con) file in Seasave
•Data format
Setting Communications Parameters in Interface Box
The PN 90488 Interface Box is shipped with default communication settings
that are compatible with operation with the SBE 21:
•9600 baud for Interface box to computer
•4800 baud for SBE 21 to Interface Box
•7 data bits, even parity (SBE 21 to Interface Box and Interface Box
to computer)
•4800 baud for NMEA device to Interface Box
If you want to change these settings, or you are using an Interface Box that
was set up for use with a different CTD, see the Interface Box manual for
details on changing communication settings.
Power and Communications Test and SBE 21 Setup in Seaterm
1. Wire the SBE 21 to the Interface Box, wire the Interface Box to the
computer, and provide power to the Interface Box, as described in
Electrical Installation in Section 3: Installing System.
2. Double click on SeaTerm.exe. If this is the first time the program is used,
the setup dialog box may appear:
Select the instrument type (SBE 21) and the computer COM port for
communication with the SBE 21. Click OK.
Notes:
•See Seaterm’s help files.
•It is possible to use the SBE 21
without Seaterm by sending direct
commands from a dumb terminal
or terminal emulator, such as
Windows HyperTerminal.
SBE21
Notes:
•Although baud rates may be set
higher than the factory defaults,
some users experience dropped
characters with higher baud rates.
•The baud rate between the
Interface Box and computer must
be equal to or higher than the baud
rate between the SBE 21 and
Interface Box.

Manual revision 027 Section 4: Setting Up SBE 21 SBE 21
20
3. The main screen looks like this:
•Menus – Contains tasks and frequently executed instrument
commands.
•Toolbar – Contains buttons for frequently executed tasks and
instrument commands. All tasks and commands accessed through the
Toolbar are also available in the Menus. To display or hide the
Toolbar, select View Toolbar in the View menu. Grayed out Toolbar
buttons are not applicable.
•Command/Data Echo Area – Echoes a command executed using a
Menu or Toolbar button, as well as the instrument’s response.
Additionally, a command can be manually typed in this area, from the
available commands for the instrument. Note that the instrument must
be awake for it to respond to a command (use Connect on the Toolbar
to wake up the instrument).
•Status bar – Provides status information. To display or hide the Status
bar, select View Status bar in the View menu.
Following are the Toolbar buttons applicable to the SBE 21:
Toolbar Description
Equivalent
Command*
Connect Re-establish communications with SBE 21. (press Enter key)
Status
Display instrument setup and status (logging, samples in memory, etc.).
DS
Headers
View data headers (header number, date and time, first and last sample, and sample interval).
New header is generated at start of logging and every subsequent 10,000 scans. DH
Init Log
Reset data pointers and cast numbers. This should be performed after existing data has been
uploaded from SBE 21 and prior to recording new data.
IL
Capture
Capture instrument responses on screen to file; may be useful for diagnostics. File has .cap
extension. Press Capture again to turn off capture. Capture status displays in Status bar.
—
Upload
Upload data stored in memory, in format Sea-Bird’s post-processing software can use.
Uploaded data has .hex extension. Before using Upload:
•Configure upload and header parameters in Configure menu.
•
Stop logging by sending QL.
DD (use Upload key if
will be data processing
with SBE Data
Processing)
Diagnostics
Perform one or more diagnostic tests on SBE 21. Test(s) accessed in this manner are
non-destructive –they do not write over any existing instrument settings. DS, FR, and VR
Stop
Interrupt and end current activity, such as uploading or diagnostic test.
(press Esc key or Ctrl C)
Disconnect
Free computer COM port used to communicate with SBE 21. COM port can then be used by
another program. —
*See Command Descriptions.
Note:
There is at least one way, and as
many as three ways, to enter
a command:
•Manually type a command in
Command/Data Echo Area
•Use a menu to automatically
generate a command
•Use a Toolbar button to
automatically generate
a command
Status bar
Menus
Command/Data Echo Area
Toolbar
Instrument
Computer
COM port
Instrument
EPROM version
Baud rate, data bits,
stop bits, and parity
Capture to file status –
grayed out if not capturing