TruTrak Digitrak Install and User Guide - Manual (Page 9)

TruTrak flight systems DigiTrak Installation Manual
October 2009 7 8300-009 Rev B
DigiTrak Ground Checkout
Must be performed before first flight
Once wiring is completed the autopilot should be tested in the aircraft while on the ground. The first step is to enter the setup
mode on the autopilot and set all parameters to their correct values. Apply power to the autopilot programmer.
When power is first applied to the unit, the display will show three flashing dash (“–”) characters. After approximately ten
seconds, the autopilot is ready to be set up for operation, indicating three non-flashing dashes on the display. (If a GPS unit
happens to be connected to the autopilot, has a valid position fix, and is running at the correct baud rate, the autopilot will
indicate the word “OFF” instead of the three dashes.)
Engage the autopilot by pressing . Then press and hold and at the same time, until the first setup screen is
displayed.
This display will show a flashing “1” and a two-digit number from 0 to 24, representing the autopilot activity level (default 6).
With the activity setup screen on the display, use
or as necessary to adjust the lateral activity value to a value of 1
or 2. Press to enter the activity value and advance to the next screen.
The second setup screen, with a flashing “2” is used to set the torque of the autopilot servo(default 12). Use or to
adjust the torque value close to the maximum value of 12. Once that is done, press to enter that value and advance to
the next screen.
The third setup screen, with a flashing “3” is used to set the baud rate (speed) of the serial interface to the GPS receiver (default
96). Use
or to select the Baud rate that matches your GPS unit. Only the first two digits are shown.
Having chosen the desired baud rate, press to enter that value and advance to the next screen.
The forth setup screen, with a flashing “4” provides the option for calibrating the internal backup magnetometer. To this
question, leave the answer set to 0 (which means “no”) at this time. This operation will be done at a later time during flight
testing.
Press to leave the setup mode. The DigiTrak display will now show “–| – |–” indicating the magnetic “heading-hold”
mode. (If GPS were indicating sufficient ground-speed for flight, the display would be showing a 3-digit selected ground track
instead.)
Press . The DigiTrak display will now return to its disengaged (off) state, which is three “–” characters if no GPS fix has
been obtained, or “OFF” if a GPS position fix has been obtained.
While the autopilot is in its disengaged (off) mode, press and hold and simultaneously. The display will now
show “–| – |–” with the center dash character blinking, indicating the Manual Gyro Set operation. Continue to hold both buttons
in for a 5 -10 seconds while the autopilot is not being moved about, to re-center the gyro manually
The next step in the check-out procedure is to verify that the servo runs, and in the correct direction. Press to again
engage the autopilot. The servo should be responding at this time, moving the controls only very slowly in attempt to hold
magnetic heading constant. Press and hold
for about 1-1/2 seconds. The autopilot will now move the controls in an
attempt to cause a constant-rate turn towards the right. If servo direction is not correct, the wires going to pins 4 and 5 of the
roll servo (pins 11 and 12 on the main connector) must be reversed to achieve the correct response. If the servo does not move
at all, double-check the torque setting (setup screen 2) to make sure it is at least 10. If a servo jitters but does not actually
rotate, check the wiring on the four servo drive lines to that servo for continuity and correctness. If the servo does not seem to
have any torque, check the roll torque control line for continuity and correctness. With a torque setting of 12, and the autopilot
engaged, the torque control line should measure approximately 4.9 volts DC.
Press and release to stop the continuous turn. Then press and hold for about 1-1/2 seconds. The autopilot will
now move the controls in attempt to cause a constant-rate turn to the left. Notice the stroboscopically-moving display
indicating the autopilot is in its constant-turn mode.
Press and release to stop the continuous turn.
While the servo is running, check that the servo arm or capstan is properly operating the controls. For servo installations using
an arm, check that as the controls go from limit to limit the arm of the servo remains in the operating range of the servo (a
maximum of 100 degrees total rotation) and that when the controls are centered, the connecting push rod is approximately
perpendicular to the arm of the servo. For capstan systems, insure that the cabling remains at proper tension and is properly