A functional module board for outputting an output signal to an application terminal, characterized in: a main board comprising a processor and a main board connector, the processor being connected to the main board connector, wherein the processor is configured to output a native signal, the main board further comprising a power slot connected to the processor and the main board connector, the power slot configured to input power to drive the processor and to transmit a standby rail power to the sub board connector through the main board connector; and a sub board comprising a sub board connector, a signal converter and a signal output terminal, the sub board connector being detachably connected to the main board connector for receiving the native signal, the signal converter being connected to the sub board connector and the signal output terminal, the signal converter configured to receive the native signal and convert the native signal into the output signal, and output the output signal through the signal output terminal, wherein a type of the signal output terminal is defined by the application terminal, the sub board further comprising a power switching component connected to the sub board connector and the signal converter, wherein the power switching component is configured to receive the standby rail power from the sub board connector, and convert the standby rail power into a main rail power of the sub board to be provided to the signal converter with a timing according to a power manage signal sent by the processor through the main board connector; wherein the sub board further comprises a signal expand component connected to the sub board connector and the signal converter, and the signal expand component is configured to amplify the native signal into a plurality of native signals, wherein the power switching component is configured to output 3.3V, 5V, or 12V as the main rail power which is provided according to requirements of a voltage and timing of the signal converter. a main board comprising a processor and a main board connector, the processor being connected to the main board connector, wherein the processor is configured to output a native signal, the main board further comprising a power slot connected to the processor and the main board connector, the power slot configured to input power to drive the processor and to transmit a standby rail power to the sub board connector through the main board connector; and a sub board comprising a sub board connector, a signal converter and a signal output terminal, the sub board connector being detachably connected to the main board connector for receiving the native signal, the signal converter being connected to the sub board connector and the signal output terminal, the signal converter configured to receive the native signal and convert the native signal into the output signal, and output the output signal through the signal output terminal, wherein a type of the signal output terminal is defined by the application terminal, the sub board further comprising a power switching component connected to the sub board connector and the signal converter, wherein the power switching component is configured to receive the standby rail power from the sub board connector, and convert the standby rail power into a main rail power of the sub board to be provided to the signal converter with a timing according to a power manage signal sent by the processor through the main board connector; wherein the sub board further comprises a signal expand component connected to the sub board connector and the signal converter, and the signal expand component is configured to amplify the native signal into a plurality of native signals, wherein the power switching component is configured to output 3.3V, 5V, or 12V as the main rail power which is provided according to requirements of a voltage and timing of the signal converter.