WATSON INDUSTRIES DMS-EGP02 User manual

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
1
DYNAMIC MEASUREMENT SYSTEM
OWNER'S MANUAL
PART NUMBER: DMS-EGP02
GPS Module & Dual Antenna System
WATSON INDUSTRIES, INC.
3041 MELBY ROAD
EAU CLAIRE, WI 54703
Phone: [phone]
FAX: [phone]
email: [e-mail]

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
2
TABLE OF CONTENTS
1. Introduction........................................................................................................ 3
2. Product Description............................................................................................ 3
3. Installation.......................................................................................................... 4
Orientation....................................................................................................................................................4
Mounting......................................................................................................................................................4
Environment.................................................................................................................................................4
Power / Connectors.......................................................................................................................................4
Calibration....................................................................................................................................................4
4. Operation............................................................................................................ 5
Initialization..................................................................................................................................................5
Normal Operation.........................................................................................................................................5
Special Operation Modes .............................................................................................................................5
Reference Mode...................................................................................................................................................5
Free Mode............................................................................................................................................................6
Hold Mode...........................................................................................................................................................6
Control Mode.......................................................................................................................................................6
Interface........................................................................................................................................................6
RS-232 Output Format ........................................................................................................................................6
RS-232 Input Commands ....................................................................................................................................8
Analog Outputs..................................................................................................................................................10
Analog Inputs ....................................................................................................................................................10
Speed Inputs ......................................................................................................................................................10
Output Logic Commands...................................................................................................................................11
Input Logic Commands .....................................................................................................................................11
5. Specifications ................................................................................................... 12
Figure 1 ......................................................................................................................................................13
6. Connections / Dimensions................................................................................ 14
Figure 2 DMS-EGP02................................................................................................................................14
Figure 3 Antenna Dimensions....................................................................................................................15
7. Warning............................................................................................................ 15
8. Appendix A ...................................................................................................... 18
Determining and Setting Output Channels.................................................................................................19
Setting Output Format................................................................................................................................20
Setting Heading Mode................................................................................................................................20
Setting Velocity Mode:...............................................................................................................................21
9. Appendix B....................................................................................................... 22
10. Appendix C....................................................................................................... 24
Watson Industries prides itself on solving customer problems and serving their needs in a timely fashion. This manual
is intended to facilitate this goal and to provide written information about your product. We ask that you carefully read
this manual. Becoming familiar with the manual will help you understand the product’s capabilities and limitations, as
well as provide you with a basic understanding of its operation. If, after reading the manual, you require further
assistance, do not hesitate to call Watson Industries with your questions and comments.

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
3
CAUTION!
Watson Sensors are rugged devices that have been used successfully in a number of harsh
environments. The components have been qualified to withstand a mechanical shock of 200g 's or
greater, and most enclosures provide an added level of protection. However, dropping a sensor
from waist height onto a hard floor can cause a shock level of 600g's. At this level, damage is
likely to occur.
Introduction
The Dynamic Measurement System (DMS) is a solid-state sensor that provides the user with
dynamic measurements of angular attitude and angular rate, together with linear acceleration, in
three (3) mutually perpendicular planes (see Figure 2). A unique feature is the two sets of
acceleration measurements. One set gives sensor acceleration with respect to the sensor mounting
face while the other set resolves the motion into horizontal and vertical components, irrespective of
the sensor attitude. This allows the earth's gravitational field to be isolated from the measurement
of sensor motion. This System consists of a DMS unit & two GPS antennas.
Product Description
Watson Industries DMS uses solid-state gyros and silicon accelerometers. Interface to the
microprocessor is done through a 16-bit A/D converter. The solid state vibrating structure angular
rate gyros used in this system provide extremely high reliability, low power consumption, shock
resistance and low cost. There are no physical adjustments required by the user. All of the primary
transducers are locked into position during manufacture. Adjustments are made with the aid of PC-
based maintenance software, which communicates with the DMS via the RS-232 serial connection.
Calibration is achieved by using the maintenance software to store data in non-volatile memory
within the DMS. The DMS-EGP02 differs from a “standard” DMS with the addition of a Dual
antenna GPS system. This allows the DMS to output actual heading instead of relative heading.
The GPS receiver also provides a vehicle velocity which is used to improve accuracy in high
dynamic environments.
This unit has two modes. A toggle switch on the front of the DMS changes the unit between modes.
The first mode, with the switch in the up position, the unit operates like a standard DMS. (See
Figure 1). The unit does not use the GPS module, it outputs relative heading, has the ability to take
in commands (double space bar mode) and the vehicle speed is an analog input. The heading needs
to be in the relative mode & velocity input needs to be in the Analog input mode. (See Appendix A
Setting Velocity & Heading Modes)
In the second mode, the DMS uses the GPS module. The switch is in the down position. (See
Figure 1). In this mode, the unit outputs actual heading, does not take in commands and the vehicle
speed is digital. Please note that the Baud Rate needs to be set to 9600 when using the GPS
module (any selectable baud rate is acceptable when the GPS module is not in use). The heading
needs to be in the GPS True North mode and velocity input needs to be in the GPS Ground Track
mode. (See Appendix A Setting Velocity & Heading Modes)
A vehicle speed input is used to assist in the correction of errors. It is also included in the
parameter set that is available for serial output. Although its use is not always required, it is highly
recommended that this signal be supplied to the DMS. The unit requires an analog/digital signal.
The analog signal is scaled to 40 KPH per volt. The digital signal is from the GPS module.
Forward motion should produce a positive signal with respect to signal ground. Many other

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
4
velocity scale factors can be handled through simple changes in the scale factor stored in the
EEPROM in the microprocessor. This can be done with a PC and the assistance of the factory.
Installation
Orientation
The connector face of the unit must point in the forward direction. The “G” command is used to
align the DMS to True North. For more information on this command, see “Setting Heading
Calibration” section of this manual. The DMS drawing, with wire call outs, is located in Figure 2.
The DMS is a rugged device and will withstand harsh environments. However, due attention needs
to be paid to the nature of the sensor and its prime function, which is to measure attitude and
motion.
Mounting
Although a mounting plate is provided for a flat surface mount, the unit may also be adhesively
mounted at any of its surfaces. If high shock loads are expected (greater than 20G or repeated
shocks greater than 10G), appropriate shock mounting should be used to prevent damage.
Vibration isolation should be used if operation in 4G or greater vibration environments is expected.
The GPS antennas have magnetic mounts with two M2.6 mounting holes and need an unobstructed
view of the sky to receive signals from GPS satellites. The “Fore” antenna is placed ½ meter ahead
of the “Aft” Antenna on a line parallel to the axis of the vehicle.
Caution: The GPS heading accuracy is directly related to the accuracy of the antenna placement &
DMS alignment. Antenna placement must be within 1 cm of the 1/2 meter spacing for accuracy.
Environment
Avoid mounting sites that are subject to significant temperature changes over the duration of the
test. Temperature variation will induce noticeable rate sensor bias drift, which will result in
degraded attitude accuracy.
Power / Connectors
This unit has an internal regulator to allow operation over a wide voltage input range. Best
operation is obtained at either 12 or 24 VDC, although operation is fully satisfactory down to 10
VDC and up to 30 VDC. Power draw of the unit is about 8.1 Watts. Internal capacitors are
provided to remove a reasonable level of power line noise, however, capacitors should be added for
long power line wiring or if noise is induced from other loads on the circuit. The DMS power
system is isolated from the DMS signal system. The mating connector for the Power/Analog
Output Connector is a 25 Pin female D-Sub. Both GPS antenna connectors are on the side. For
more information on the connectors and pinout of the DMS-EGP02, see Figure 2.
Calibration
The DMS is calibrated at the factory before it is shipped to the user. It is recommended that the
unit be returned to the factory annually for evaluation and recalibration.

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
5
Operation
Initialization
Ideally, the DMS should be stationary and level when it is turned on. If not, the sensor readings
may not be accurate after initialization. The time required for the initialization process is not the
same for every type of DMS, but typically takes 4 to 5 seconds. During this time, a message is sent
from the unit via the RS-232 serial link. This message gives information about the DMS such as
the full model number, serial number, and software revision. The message can be read by using a
terminal program or by using the terminal mode of Watson Industries’ communication software.
The DMS can also be “re-initialized” after it has been turned on. This is especially useful if the
sensor has been used in severe maneuvers that have over-ranged the angular rate sensors and
caused significant errors to accumulate. Sometimes re-initializing the unit will allow for a faster
recovery than waiting for the error correction routines to correct the sensor readings. There are
several ways to re-initialize the DMS. For more information, see the Interface section of this
manual. Please note that in order to use the GPS mode of this unit, the switch must be in the down
position when the unit is initialized or re-initialized (See Figure 1).
Normal Operation
During normal operation, the DMS will output highly accurate inertial data for the user to interpret.
This data is transmitted in several different ways. The most common way to acquire data from the
DMS is to use the RS-232 serial output. There are two RS-232 output formats: decimal and binary.
The exact formatting structure is discussed later in the Interface section of this manual. The DMS
generates twelve different data items for output: X, Y, and Z rates, X, Y, and Z accelerations, Bank,
Elevation, and Heading, and Forward, Lateral, and Vertical Accelerations. Any combination of
these data items can be selected for transmission via the RS-232 serial link. The DMS also has
analog outputs (see Interface section) that can be used to send data to the user.
In normal operation, the DMS takes data from its internal rate sensors and integrates in a closed
loop system, with the accelerometers as a long-term reference, to generate Bank, Elevation and
Heading data. In most cases, these algorithms provide for very stable and accurate output signals;
However, the user should be aware that exceeding the normal ranges of the sensors will affect
accuracy. For example, while custom DMS units may have differing ranges, the gyros in a typical
DMS have a maximum rate of 100°/s. Care should be taken not to exceed this rate because the
closed loop system will receive inaccurate data. This will result in errors in the angle output
signals.
While this DMS is "all attitude", the accuracy deteriorates rapidly when its forward direction is
within about 5 degrees of vertical. Operation for any extended period of time in this orientation is
not recommended. If these few operational precautions are observed, the DMS should provide
very accurate data for a wide variety of applications.
Special Operation Modes
Reference Mode
This mode is usually used for calibration or diagnostics. When in reference mode, the DMS will
output data generated directly from the sensor reference signals rather than as a product of the
closed loop integration used for normal operation. This mode provides sensor information similar
to normal operation mode with the following differences:

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
6
Bank and Elevation are obtained directly from the accelerometers - no gyro stabilization.
No heading information is available.
Angular Rate Sensors are not close-loop bias corrected.
The reference mode can be selected either through the terminal mode, or by an analog logic
command. Note that reference mode is never a default setting. It must be re-selected when re-
powering the unit.
Free Mode
While in Free Mode, the DMS will output data from the sensors without correction by the
references. For example, the Bank Angle data output in Free Mode is calculated directly from the
X axis Rate Sensor. In this case, the angle is a direct integration of the roll rate. Free Mode can be
used to totally reject effects from dynamic accelerations, but accuracy degrades with time. It is
intended for use over periods of a minute or two at a time. This mode provides sensor information
similar to normal operation mode with the following differences:
Bank and Elevation are obtained directly from the rate gyros.
Relative heading information is available.
Angular Rate Sensors are not close-loop bias corrected.
Free mode can be accessed either through terminal mode, or by an analog logic command. Note
that free mode is never a default setting. It must be re-selected when re-powering the unit. The
user should not enter free mode until after the DMS is initialized and its readings are stable.
Hold Mode
This mode inhibits bias adjustments to the gyros. It is intended for short-term use only since
leaving biases uncorrected will allow errors to accumulate over time. The accumulating bias error
will result in small attitude errors. Hold mode can provide better performance in highly dynamic
environments such as continuous circling over several minutes time. The user should not enter hold
mode until after the DMS is initialized and its readings are stable.
Control Mode
In this mode, the DMS will output sensor data normally unless it receives a control mode
command. Once a command is received, the DMS will send data in response and await the next
command. Using this mode, the user can retrieve the EEPROM map, baud rates, output formats,
and many other operational settings of this sensor. Having access to this information makes the
Control Mode useful in assisting the factory to remotely troubleshoot the certain operational
problems that can occur. For more details, see the RS-232 Input Commands section later in this
manual.
Interface
The DMS has analog, logic, and digital interface capabilities.
RS-232 Output Format
The standard RS-232 output consists of a string of decimal ASCII characters sent asynchronously
at regular intervals. Nominally, the string is sent at 9600 baud with eight data bits, one stop bit and
no parity. The mating connector for the RS-232 is a 9 Pin Male D-Sub. The RS-232 signal is
referenced to signal ground. The number of strings sent per second depends on the baud rate and
the output format. The maximum rate is 71.11 strings per second. See Appendix A for information
on how to change the data string. The contents of a typical string are formed as follows:

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
7
1. A single letter and a space used to indicate the start of the data string. The letter “G”
indicates the start of an inertial data string with successful GPS data input. The letter “I”
indicates the start of an inertial data string with GPS disabled or absence of valid GPS data.
The letter “R” indicates the start of a Reference data string. If the letter is in lower case
(“g”,“i”, or “r”), an error over-range condition is indicated (see below).
2. A seven character string representing the bank angle starting with a “+” or a “-“, followed
by three digits, a decimal point, one digit and a space for up to ±179.9 degrees.
3. A six character string representing the elevation angle starting with a “+” or a “-“, followed
by two digits, a decimal point, one digit and a space for up to ±89.9 degrees.
4. A six character string representing the heading angle by three digits, a decimal point, one
digit and a space for zero to 359.9 degrees.
5. A six character string representing the X axis acceleration starting with a “+” or a “-“,
followed by one digit, a decimal point, two digits and a space for up to ±9.99 g’s.
6. A six character string representing the Y axis acceleration starting with a “+” or a “-“,
followed by one digit, a decimal point, two digits and a space for up to ±9.99 g’s.
7. A six character string representing the Z axis acceleration starting with a “+” or a “-“,
followed by one digit, a decimal point, two digits and a space for up to ±9.99 g’s.
8. A six character string representing the X axis angular rate starting with a “+” or a “-“,
followed by two digits, a decimal point, one digit and a space for up to ±99.9
degrees/second.
9. A six character string representing the Y axis angular rate starting with a “+” or a “-“,
followed by two digits, a decimal point, one digit and a space for up to ±99.9
degrees/second.
10. A six character string representing the Z axis angular rate starting with a “+” or a “-“,
followed by two digits, a decimal point, one digit and a space for up to ±99.9
degrees/second.
11. A seven character string representing the Forward Velocity starting with a “+” or a “-“,
followed by three digits, a decimal point, one digit and a space for up to ±399.9 Km/Hr.
12. The string is terminated by a carriage return. There will then be a short interval with no
data transmission before the next string begins.
Example:
G -000.4 +00.1 273.4 +0.00 +0.00 -1.00 -00.4 +00.2 +00.4 +017.3 <CR>
↑↑↑↑ ↑↑↑↑ ↑ ↑
(1)
Bank
angle
(2)
elev.
angle
(3)
Head.
angle
(4)
X
Acc
(5)
Y
Acc
(6)
Z
Acc
(7)
X
Rate
(8)
Y
Rate
(9)
Z
Rate
(10)
Forward
Velocity
(11) (12)
space space space space space space space space space space
The string transmission rate can be improved by reducing the amount of information (data items)
transmitted. The data items transmitted can be changed by using special commands to modify the

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
8
EEPROM of the unit (see Appendix A). In addition, more channels are available for output (see
Appendix A).
The system is protected from inadvertent write-over of the EEPROM by requiring two spacebar
commands during the initialization interval to access the EEPROM or related functions.
The baud rate may be changed from the nominal value of 9600 baud by modifying the default
value in the EEPROM of the unit to 38.4K, 19.2K, or 4800 baud. Please note that the Baud Rate
must be 9600 when using the GPS module.
A text header is sent by the DMS during initializations that identifies the unit by part number and
by serial number and gives the date of last calibration. Additionally, a line of text characters that
identifies the data channel columns is sent if the serial output is set to ASCII decimal. This whole
message can be temporarily (or as a default) suppressed or restored by a “*” command from the
interfacing computer.
Data transmission sent by the DMS can also be suppressed or restored by a “+” command from the
interfacing computer. This is used when only analog data is used as a noise reduction measure.
The error over-range condition is indicated by the use of a lower case “i”, “g” or “r” when the
calculated attitude or heading error exceeds the ranges listed above. Internal functions that require
these error values are disabled while the condition exists. The system will continue to operate in an
extended time constant mode with a low level of error accumulation until the condition is cleared.
While maneuvering the vehicle, occasional blips of this condition are expected with no detectable
effect on the resulting data.
The other output format available is a binary format. In this mode, the unit provides generally the
same information as the decimal ASCII format, but in a compact binary message. In this format,
there are nominally 13 words sent that represent 6 fourteen-bit output channels followed by a
carriage return. Again, the channels may be reduced to improve the update rate by using special
commands to modify the EEPROM of the unit. This format is for highly experienced users only.
Consult the factory for further details.
RS-232 Input Commands
The RS-232 input commands are provided for the purpose of unit test and installation set-up.
Please note these commands are only available when the switch is in the up position. (See Figure
1). The same parameters are used as for the output (9600 baud ASCII nominal, or as reset in the
units EEPROM). There are eight commands intended for use by the user (others are used at the
factory for alignment and calibration). A double spacebar keyed in during the initialization interval
is required for access to most of these commands. The initialization interval is the period of time
that the unit takes to send the startup message and start outputting data. The two consecutive
spacebar commands must be received during the initialization interval; Any more or less will
invalidate the command. Any other characters sent to the unit during this time will also invalidate
the command.
1. An “R” or “r” will set the outputs (analog and serial) to their Reference Command modes
replacing the Inertial mode. This will also disable the logic input Reference Command and
Free Mode Command until the next time the unit is powered up. This mode is used in
installation to physically align the unit. Double spacebar at initialization is required for
access to this command.

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
9
2. An “I” or “i” sets the unit to Inertial mode. This is the default mode at power up and is the
normal operating mode. Switching to this mode clears the Reference Command mode.
This will also disable the logic input Reference Command and Free Mode Command until
the next time the unit is powered up. Double spacebar at initialization is required for access
to this command.
3. An “F” or “f” will disconnect the references from the attitude system and is the Free Mode
Command. Free mode is used to make the system ignore the references during high
maneuvers and brief disturbances. This mode is not intended for use except in brief
intervals, since errors will grow geometrically. This will also disable the logic input
Reference Command and Free Mode Command until the next time the unit is powered up.
This command does not require a double space bar at initialization to be in effect.
4. An “H” or “h” will remove bias correction from the system and is the Hold Mode
Command. This mode is useful is highly dynamic situations that may last for a few minutes.
Hold mode should not be used for more than a few minutes, because errors can accumulate.
This command does not require a double space bar at initialization to be in effect.
5. A “K” or “k” will clear the Free Mode Command and the Hold Mode Command.
6. An “!” will reinitialize the unit. Further, the access to initialization is inhibited such that a
spacebar command must be sent within 2.5 seconds of the “!” command for initialization to
be engaged. This command does not require a double space bar at initialization to be in
effect.
There are two output format commands: “_” for decimal output and “^” for binary. See second part
of Appendix A for more information on changing output formats. There are several interface
commands as well: “:” will toggle the output to send a frame of data upon receiving any non-
command character and “+” will toggle the output for no output data. These and other changes
can be made permanent by keying in the quote (“) character. Double spacebar at initialization is
required for access to all of these commands.
The “&” command calls a menu which allows any of several parameters to be set. From this menu,
the user can change system time constants, data channels for serial output, heading source, velocity
source and baud rate. Double spacebar at initialization is required for access to this command.
The commands “~”, “@”, “#”, “$”, ‘(“, “)”, “{“, “}”, “|”, “<”, “>” and “?” are used by the Watson
factory to calibrate the unit and should be used only with the assistance of the factory. If an
undesired function is called, a “Q”, and sometimes Escape or a Delete will interrupt the command
and return to operation with the least disturbance to the system. All other unspecified characters
such as carriage return, line feed and space are ignored by the system.
If there are problems with the system “hanging up” during the binary output mode, check for cross-
talk between the serial transmit and receive line in your installation. In addition, check to see that
the communications program used is not sending an echo. This will not happen in the decimal or
hexadecimal modes because command characters recognized by the system are not produced in
those modes. Please note that the signal and power ground are isolated from one another.

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
10
Analog Outputs
Analog signals are output from a 12 bit digital to analog converter with a series resistor to protect
the analog buffer amplifier. The output range for all of the analog output channels is ±10 Volts
with respect to the common signal ground. The outputs include:
Data Pin Range
Bank 14 ±180°/ ±10V
Elevation 15 ±90°/ ±5V
Heading 16 0-360°/ ±10V
Roll Rate (X Axis) 23 ±100°/s / ±10V
Pitch Rate (Y Axis) 24 ±100°/s / ±10V
Yaw Rate (Z Axis) 25 ±100°/s / ±10V
X Acceleration 17 ±10G / ±10V
Y Acceleration 18 ±10G / ±10V
Z Acceleration 19 ±10G / ±10V
Forward Acceleration 20 ±10G / ±10V
Lateral Acceleration 21 ±10G / ±10V
Vertical Acceleration 22 ±10G / ±10V
Note that the analog switches are disabled after certain serial commands are sent to the unit. This
prevents software/hardware switch conflicts.
Analog Inputs
In an effort to make this system more versatile, the DMS allows the user to input analog data that
can then be added to the serial data output. This allows the system to act as a data acquisition unit
for other vehicle information such as engine RPM, engine temperature, fuel remaining,
altitude/depth or any other important data. The four analog user inputs as well as the velocity input
have one megohm input impedance, 16 bit A/D conversion resolution, ±10 volt input range and
have a bandwidth of DC to 25 Hertz.
Speed Inputs
A vehicle speed input is used to assist in the correction of errors. It is also included in the
parameter set that is available for serial output. Although its use is not always required, it is highly
recommended that this signal be supplied to the DMS. The unit can receive speed information in
two formats, an analog or digital signal. The internal GPS receiving unit provides the digital
signal.
The optional analog speed input signal is a voltage that is scaled to 40 KPH per volt. Forward
motion should produce a positive signal with respect to signal ground. Many other velocity scale
factors can be handled through simple changes in the scale factor stored in the EEPROM in the
microprocessor. This can be done with a PC and the assistance of the factory.

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
11
Output Logic Commands
Initialization lasts 5 seconds, during which time the "Ready" signal is set low (0v). Once
Initialization is complete, the "Ready" signal is set high (+5VDC). The ready signal is on pin 9 of
the 25 pin connector.
Input Logic Commands
The DMS also has several digital inputs that are all activated by connecting to signal ground. The
user should only apply a ground because all the inputs have a internal pull-up resistor to +5VDC.
The pins are as follows:
a) Initialization - Resets all angle integrators. The unit should be in a non-accelerated
condition if this command is given. Leave pin open if not in use. Ground to command.
b) Reference - An alternate set of sensor information primarily intended as an
instrumentation mode. Leave pin open if not in use. Ground to command.
c) Free Inertial Mode – In this mode, the attitude is computed from gyro data only. Free
mode is used when extreme accelerations are expected. Leave pin open if not in use.
Ground to command.
NOTE: The digital logic inputs are all disabled if any one equivalent serial command is sent via
RS-232. This is to prevent hardware/software conflicts.

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
12
Specifications
Attitude
Range: Bank ±180°
Range: Elevation ±75°
Resolution: 0.02° Binary mode (14 bit)
Analog Scale Factor: 18°/V ±10V Output
Accuracy: Static ±0.25°
* Accuracy: Dynamic ±2%
Heading
Range: 0° - 360°
Resolution: 0.02° Binary mode (14 bit)
Analog Scale Factor: 18°/V ±10V Output
Accuracy: Static (Using GPS) ±0.5°
* Accuracy: Dynamic ±2%
Angular Rate
Range: Roll, Pitch, Yaw ±100°/sec
Resolution: 0.01°/sec Binary mode (14 bit)
Analog Scale Factor: 10°/sec/V ±10V Output
Scale Factor Accuracy: 1%
Bias: Roll, Pitch, Yaw < ±0.02°/sec
Non-Linearity < 0.03% Full scale range
Bandwidth 20 Hz
Acceleration
Range: X, Y, Z ±10g
Range: Forward, Lateral, Vertical ±10g
Resolution: 4mg
Analog Scale Factor: 1g/V ±10V Output
Scale Factor Accuracy: 1%
Bias: X, Y, Z < ±5mg
Non-Linearity: < 1% Full scale range
Bandwidth: 20 Hz
Environmental
Temperature: Operating -30°C to +60°C
Temperature: Storage -55°C to +85°C
Vibration: Operating 5g rms 20 Hz to 2 kHz
Vibration: Survival 10g rms 20 Hz to 2 kHz
Shock: Survival 500g 10ms ½ sine wave
Electrical
Frame Rate 71.1 Hz Maximum
Startup Time: Data 5 sec
Startup Time: Fully operational < 60 sec Typical
Input Power: 10 to 30VDC 8.1 W
Input Current: 675mA @ 12VDC 338mA @ 24VDC
Input Velocity: (Optional) ±10VDC Full scale (±400kph)
Digital Output RS-232
Analog Output ±10VDC
Physical
Axis Alignment: < 0.1°
Size: Including Mounting Flanges 6.5”W x 6.5”L x 3.75”H 16.5 x 16.5 x 9.5 (cm)
Weight: 54oz (3.4lb) 1531g (1.5kg)
Connection: RS-232 9 pin female “D” subminiature
Connection: Power / Analog Outputs 25 pin male “D” subminiature
Connection: GPS (Qty 2) SMA
* Using velocity data with GPS mode on.
Actual accuracy can be calculated as the listed percentage multiplied by the change in value over the entire dynamic maneuver.
Specifications are subject to change without notice.

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
13
Figure 1
Up Position - Receive from 9-pin connector
This is non-GPS mode. Allows Keyboard commands to
be input into the unit.
Down Position – Receive from GPS module. This is the
GPS mode. Keyboard commands are not recognized.

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
14
Connections / Dimensions
25 Pin Male D-Sub Power/Analog Output Connector
9 –Pin Female D-Sub
RS-232 Serial
Communication Connector
Pin Description Pin Description Pin Description
1 Power Ground * 15 Elevation Angle Analog Output 1 No Connection
2 +12 or +24 VDC 16 Heading Angle Analog Output 2 TXD**
3 - 6 User Inputs 1 - 4 17 X Axis Acceleration Analog Output 3 RXD
7 Not Used 18 Y Axis Acceleration Analog Output 4 Shorted to pin 6
8 Coast Command 19 Z Axis Acceleration Analog Output 5 Ground
9 Ready 20 Forward Acceleration Analog Output 6 Shorted to pin 4
10 Initialization Command 21 Lateral Acceleration Analog Output 7 Shorted to pin 8
11 Velocity Input (option) 22 Vertical Acceleration Analog Output 8 Shorted to pin 7
12 Signal Ground 23 Roll Rate Analog Output 9 No Connection
13 Reference Command 24 Pitch Rate Analog Output
14 Bank Angle Analog Output 25 Yaw Rate Analog Output ** The user receives on
this line.
* Power Ground & Signal Ground are electrically isolated
Figure 2 DMS-EGP02

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
15
Figure 3 Antenna Dimensions
Warning
Rough handling, dropping, or miswiring this unit is likely to cause
damage.

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
16
DISCLAIMER
The information contained in this manual is believed to be accurate and reliable; however, it is the
user’s responsibility to test and to determine whether a Watson Industries’ product is suitable for a
particular use.
Suggestion of uses should not be taken as inducements to infringe upon any patents.
WARRANTY
Watson Industries, Inc. warrants, to the original purchaser, this product to be free from defective
material or workmanship for a period of two full years from the date of purchase. Watson
Industries’ liability under this warranty is limited to repairing or replacing, at Watson Industries’
sole discretion, the defective product when returned to the factory, shipping charges prepaid, within
two full years from the date of purchase. The warranty described in this paragraph shall be in lieu
of any other warranty, express or implied, including but not limited to any implied warranty of
merchantability or fitness for a particular purpose.
Excluded from any warranty given by Watson Industries are products that have been subject to
abuse, misuse, damage or accident; that have been connected, installed or adjusted contrary to the
instructions furnished by seller; or that have been repaired by persons not authorized by Watson
Industries.
Watson Industries reserves the right to discontinue models, to change specifications, price or
design of this product at any time without notice and without incurring any obligation whatsoever.
The purchaser agrees to assume all liabilities for any damages and/or bodily injury which may
result from the use, or misuse, of this product by the purchaser, his employees or agents. The
purchaser further agrees that seller shall not be liable in any way for consequential damages
resulting from the use of this product.
No agent or representative of Watson Industries is authorized to assume, and Watson Industries
will not be bound by any other obligation or representation made in connection with the sale and/or
purchase of this product.
PRODUCT LIFE
The maximum expected life of this product is 20 years from the date of purchase. Watson
Industries, Inc. recommends the replacement of any product that has exceeded the product life
expectation.

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
17
SERVICE
Watson Industries, Inc. has no service outlets. All service is performed at the factory. In order to
insure prompt service, prior to returning units for repair please call, write or fax:
Watson Industries, Inc.
3041 Melby Road
Eau Claire, WI 54703
ATTN: Service Department
Telephone: [phone]
Fax: [phone]
Email: [e-mail]
All sensors returned under warranty will be repaired (or replaced at the sole option of Watson
Industries) at no cost to the customer other than shipping charge from customer to Watson
Industries (plus any export and transportation charges outside the United States).
In the case of units not under warranty, a flat repair fee will be charged. This fee can be
determined by contacting Watson Industries. Modified units or those subjected to extreme abuse
may be returned to the customer unrepaired.

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
18
Appendix A
The following outputs are available via the RS-232 serial link. Their full scale ranges are listed for both decimal and
binary format.
Inertial Output Full Scale Decimal Full Scale Binary
Time Since Reset 65,535 seconds 16,383 seconds
Bank Angle ±179.9º ±180º
Elevation Angle ±89.9º ±180º
Heading Angle 0.0 to 359.9º ±180º
X Accelerometer ±9.99 G ±10 G
Y Accelerometer ±9.99 G ±10 G
Z Accelerometer ±9.99 G ±10 G
Forward Acceleration ±9.99 G ±10 G
Lateral Acceleration ±9.99 G ±10 G
Vertical Acceleration ±9.99 G ±10 G
X Angular Rate ±99.9 º/s ±200 º/s
Y Angular Rate ±99.9 º/s ±200 º/s
Z Angular Rate ±99.9 º/s ±200 º/s
Heading Rate ±99.9 º/s ±200 º/s
Corrected Bank Pendulum (simulated)
±179.9º ±180º
Corrected Elevation Pendulum (simulated)
±89.9º ±180º
User Channel 1 ±9.99 VDC ±10 VDC
User Channel 2 ±9.99 VDC ±10 VDC
User Channel 3 ±9.99 VDC ±10 VDC
User Channel 4 ±9.99 VDC ±10 VDC
Forward Velocity ±399.9 Km/hr ±400 Km/hr
Temperature -40º to 88ºC -40º to 88ºC (7 bit)
Status Bits 1 byte 1 byte
Flag Bits 1 byte 1 byte
The Status Bits contain the following information:
Bit Description (If Set)
0 Bank Error Flag
1 Elevation Error Flag
2 Heading Error Flag
3 System Error Flag
4 Velocity Error Flag
5 Ready Flag
6 Checksum Error Flag
The Flag Bits contains the following information:
Bit Description (If Set)
0 GPS ground track heading data loss
1 GPS ground track velocity data loss
2 GPS true heading data loss
3 Reference Command selected
4 GPS enabled
5 Free Mode selected
6 Logic Input Switches disabled

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
19
Determining and Setting Output Channels
To determine which channels are present.
Hook the unit up to your computer’s serial port.
Use a terminal program to interface with the unit.
Make sure the switch is in the up position so that unit can receive computer commands.
Turn on unit. Wait for the startup message to appear on display.
Hit the space bar twice within the first 5 seconds of turn on.
Sometimes it takes a few tries to get the hang of this.
Wait for the data string to start transmitting.
Now the unit will take in keyboard commands.
To determine which channel present, first type '&'.
This will bring up the menu:
Typing in '3' will show which channels are currently active.
To change which channels are output type '&'(this will bring up the menu again)
Now type '2' to set up channels
The following message will appear:
To proceed type 'Y' or ‘y’
Now each channel will come up one at a time
For example:
Type 'Y'or ‘y’ to output channel, type 'N' or ‘n’ to remove channel
When you get to bottom of list, this message will appear:
To accept channels type 'N', then hit space bar output data to resume.
To make this channel selection the default the next time you power the unit on type in " (a quote mark)
TYPE IN THE NUMBER OF YOUR SELECTION (OR 'Q' TO QUIT):
1 = ADJUST TIME CONSTANTS
2 = SET OUTPUT CHANNELS
3 = LIST CURRENT OUTPUT CHANNEL SELECTION
4 = SELECT HEADING SOURCE
5 = SELECT VELOCITY SOURCE
6 = SET NEW BAUD RATE
TO SET FOR OUTPUT FOR ANY OF THE FOLLOWING DATA ITEMS, PRESS Y
TO AVOID ANY OF THE FOLLOWING DATA ITEMS, PRESS N
TO QUIT AND DISREGARD ANY OTHER DATA, PRESS Q
*** DO YOU WANT TO PROCEED? (Y/N/Q)
DO YOU WANT OUTPUT OF BANK ANGLE?
Y = GOBACK, N = INSTALL DATA & QUIT, Q = QUIT
DO YOU WANT TO TRY TO SET DATA AGAIN?

Watson Industries, Inc. DMS-EGP02 Rev A 03/28/2008
20
Setting Output Format
There are two output formats:
Decimal output – “_” Command.
Binary output – “^” Command.
To change the output format:
Hook the unit up to your computer’s serial port.
Use a terminal program to interface with the unit.
Make sure the switch is in the up position so that unit can receive computer commands.
Turn on unit. Wait for the startup message to appear on display.
Hit the space bar twice within the first 5 seconds of turn on.
Sometimes it takes a few tries to get the hang of this.
Wait for the data string to start transmitting.
Now the unit will take in keyboard commands.
Press the key Command corresponding to the format you want to switch into.
To make this channel selection the default the next time you power the unit on type in " (double quote.)
Setting Heading Mode
Hook the unit up to your computer’s serial port.
Use a terminal program to interface with the unit.
Make sure the switch is in the up position so that the unit can receive computer commands.
Turn on unit. Wait for the startup message to appear on display.
Hit the space bar twice within the first 5 seconds of turn on.
Sometimes it takes a few tries to get the hang of this.
Wait for the data string to start transmitting.
Now the unit will take in keyboard commands.
To set the heading mode, type in &.
This will bring up the menu:
Typing in 4' will bring up this menu:
To set the heading mode to GPS True North Heading type ‘1’. After setting the unit to this mode, the switch needs to
be in the down position. To use this mode, the GPS antenna must be connected to the DMS.
To set the heading mode to Relative Heading type ‘2’. This is the normal DMS mode (non-GPS). In this mode, the
GPS antenna does not need to be connected.
To make any of these modes the default the next time you power the unit on type in " (double quote)
TYPE IN THE NUMBER OF YOUR SELECTION (OR 'Q' TO QUIT):
1 = ADJUST TIME CONSTANTS
2 = SET OUTPUT CHANNELS
3 = LIST CURRENT OUTPUT CHANNEL SELECTION
4 = SELECT HEADING SOURCE
5 = SELECT VELOCITY SOURCE
6 = SET NEW BAUD RATE
SELECTION HEADING SOURCE (OR 'Q' TO QUIT):
1 = GPS TRUE NORTH HEADING
2 = RELATIVE HEADING