AHRS-E304 Watson Industries, Inc
09/06/05
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6.
A “C” will clear the Invalid Velocity Command. Double spacebar at initialization is
required for access to this command.
7.
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.
8.
An “L” in the decimal mode will return a line of characters which will identify the data
columns. Double spacebar at initialization is required for access to this command.
There are two output format serial commands: “_” for decimal output and “^” for binary. 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 are made non-volatile in the unit on EEPROM by keying in the quote (“)
character. Double spacebar at initialization is required for access to these commands.
To provide a calibration means, a command may be used to offset the heading output from any
given angle to North. To use this, simply aim the vehicle platform to the North reference
required, set an “R” command on the keyboard and then send an upper case “N”. This is a
nonvolatile correction, can be used with any North reference, will correct most local magnetic
distortions. Double spacebar at initialization required for access to this command.
The “&” command calls a menu which allows any of several parameters to be set. These are
system time constants, selection of data channels for serial output and baud rate. Double
spacebar at initialization is required for access to this command.
The commands “~”, “@”, “#”, “$”, “(“, “)”, “{“, “}”, “|”, “<”, “>”, “S”, “M”, “X”, “T”, “D”, 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
crosstalk 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 mode because command characters recognized by the system are not produced in this
mode.
ANALOG INPUTS
In an effort to make this system more versatile, this system 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.
