The VP-X controls the trim motor as well as provides the circuitry to report the trim position to the EFIS. It also handles runway or faulted trim conditions, and enables the EFIS to control the trim from the screen. All of the trim wiring is connected directly to the VP-X, and the trim position is reported to the EFIS over the serial data line. The trim motor circuit breakers are set at 1 amp, and are not configurable.
Most experimental aircraft use trim servos from the Ray Allen Company. These servos are self-contained units that include the trim motor as well as a position sensor. These servos are designed to run at 14 volts, and the VP-X Pro provides regulated 14v power to the trim motors so they can operate safely in 14v or 28v systems. The general principles described in this section apply to other brands of trim motor as well.
Connecting the trim motor to the VPX:
The trim motor itself is driven by the two white wires. It does not matter how they are connected, as the polarity can be changed using the VP-X Configurator. The direction of travel is controlled by reversing the positive and negative connections to the trim motor.
(VP-X Install Manual, Rev E, 2021)