AHRS-E304 Watson Industries, Inc
09/06/05
8
ANALOG OUTPUTS
The analog outputs are operational amplifier driven so they are limited in drive capacity. Each
analog output has a 300 ohm resistor in series internal to the AHRS to eliminate oscillations from
high capacitance loads. The analog output voltage range is ±10VDC.
OUTPUT FLAGS
There are two output flags. The South Heading flag indicates that the heading is greater than 90°
and less than 270°. The Velocity Error flag indicates acceleration or centrifugal force
corrections exceed 45° or the velocity input is over-range (greater than 800 Km/hr. or less than -
800 Km/hr.).
RS-232 INPUT COMMANDS
The RS-232 input commands are provided for the purpose of unit test and installation set-up.
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).
1.
An “R” or “r” will set the outputs (analog and serial) to their Reference Command
modes. This will also disable the logic input Reference Command, Coast Mode
Command and Invalid Velocity 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.
2.
An “I” or “i” will clear the Reference Command mode if it had been set by the serial
input. This is the default mode at power up and is the normal operating mode. This will
also disable the logic input Reference Command, Coast Mode Command and Invalid
Velocity Command until the next time the unit is powered up. Double spacebar at
initialization is required for access to this command.
3.
An “F” will disconnect the references from the attitude system and is the Coast Mode
Command. This coast 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, Coast Mode Command and Invalid Velocity Command until the
next time the unit is powered up. Double spacebar at initialization is required for access
to this command.
4.
A “K” will clear the Coast Mode Command. Double spacebar at initialization is required
for access to this command.
5.
A “V” will disconnect the velocity input from the attitude system and is the Invalid
Velocity Command. This mode is used to protect the system from accumulating errors
when the velocity reference is not functioning. This will also disable the logic input
Reference Command, Coast Mode Command and Invalid Velocity Command until the
next time the unit is powered up. Double spacebar at initialization is required for access
to this command.
