IFD 5 Series & IFD 4 Series Touch Screen GPS/NAV/COM

Photo Maximum

The Photo Maximum sets the maximum brightness when the dimming source is the photocell. Both the Bezel and Display fields have a range of 50 to 100, and the factory default is 100.

dimBus Transition %

The dimBus Transition % sets the threshold where the aircraft dimming bus takes over from the photocell. Below this threshold, the aircraft dimmer controls the IFD5XX lighting. Both the Bezel and Display fields have a range of 0 to 100, and the factory default is 10.

Note: If it is not desired to hand brightness control over to the dimming bus from the photocell at any point, set dimBus Transition % to 0 (zero). Doing so will prevent the scenario where, in increasingly darker environments (e.g. flying past sunset into dark night), the display automatically dims and dims and dims and then suddenly jumps to bright.

dimBus Slope

The dimBus Slope sets the sensitivity of the display/bezel to the aircraft dimmer. Both the Bezel and Display fields have a range of 15 to 100, and the factory default is 60.

dimBus Minimum

The dimBus Minimum sets the minimum brightness when the aircraft dimmer is the dimming source. Both the Bezel and Display fields have a range of 1 to 50, and the factory default is 1.

dimBus Maximum

The dimBus Maximum sets the maximum brightness when the aircraft dimmer is the dimming source. Both the Bezel and Display fields have a range of 50 to 100, and the factory default is 100.

dimBus Curve

The dimBus Curve sets the aircraft dimming bus to either a Proportional Curve or AviCurve on the IFD5XX.

The Proportional Curve tracks the aircraft lighting bus as follows: Maximum night lighting at maximum aircraft lighting bus voltage, Minimum night lighting at minimum aircraft lighting bus voltage (linear in-between).

Field	Selection
Bezel	Value displayed represents the current % brightness of the bezel backlighting
Display	Value displayed represents the current % brightness of the display backlighting
Mx Input	Photocell – Maintenance Mode will use this method if selected. This is the default setting. This setting uses the Photocell on the IFD5XX bezel or display. dimBus – Maintenance Mode will use this method if selected. This setting uses the aircraft lighting buss to control the lightning of the bezel or display.

For those who want to use the dimming bus, it's important to calibrate the dimming bus for the IFD.

Dimming Bus Calibration

The section will calibrate the IFD5XX to the aircraft avionics lighting bus.

Selection	Description
dimBus Type	DC – select this option if the dimming bus is a DC bus. AC – select this option if the dimming bus is an AC bus. The IFD needs to know the bus type in order to alter internal configuration as well as properly perform the calibration.
dimBus Max Voltage	Sets the maximum aircraft dimming bus voltage. Range is 0 – 28V.
dimBus Min Voltage	Sets the minimum aircraft dimming bus voltage. Range is 0 – 28V.

To calibrate the dimming bus:

Select desired dimBus Type;
Select the dimBus Max Voltage field;
Push the right bezel knob;
Set the dimming bus to the maximum value (e.g. full clockwise position on dimming rheostat);
Push the right bezel knob to store;

Repeat the process for the minimum value (use full counter-clockwise position of rheostat)

As for triggering the IFD540 generated audible alerts on the ground, there is no real way to do that until Rel 10.1 comes along in the spring. We've tweaked the design to allow any adjustments to play the volume in your headsets when adjusting.