Add pull-up resistors to ensure proper voltage levels on input signals.
In some cases, you must add pull-up circuitry to connect an output device to an auxiliary input signal; specifically, you must attach an external pull-up resistor between the voltage source and the AUX_IN pin.
This is required when connecting the AUX_IN_COMMON pin to the electrical return path, and the third-party output device is in a sinking configuration.
In this case, select a resistor value that does not overcurrent the output device and provides enough current and voltage to the scanner's auxiliary input signals.
Use a resistor with an appropriate power rating for your circuit.
