AHRS-E304 Watson Industries, Inc
09/06/05
10
INPUT LOGIC COMMANDS
To aid in alignment and testing, the AHRS-E304 is equipped with a Reference Command input.
By grounding this pin (pin 13), the mode of the unit is changed so that the pendulums and
magnetometer generate the output in place of the usual gyro outputs. When not in use the pin is
to be left unconnected. This input is disconnected until the next power-up by activating some of
the RS-232 command set (sending a serial command “I”, “R”, “F” or “V”).
An Invalid Velocity input command is used to turn off velocity related corrections when the
velocity input is untrustworthy. By grounding this pin (pin 12), the mode of the unit is changed
so that the velocity input has no influence. The same effect can be obtained by holding the
velocity input to zero. When not in use the pin is to be left unconnected. This input is
disconnected until the next power-up by activating some of the RS-232 command set.
The Coast Mode Command input, when grounded (pin 25), will disconnect the references from
the attitude system. The main use of this is to isolate the system from errors during highly
dynamic maneuvers. This mode is not intended to be used for time spans greater than a minute
or two because of the growth of errors in the attitude integrals. When this command is released,
the system will return to normal error correction operation. When not in use the pin is to be left
unconnected. This input is disconnected until the next power-up by activating some of the RS-
232 command set.
