Some devices allow not connecting the ignition cable to the input of the device to transmit the ignition status, but to use virtual ignition based on the motion sensor readings or the vehicle's on-board voltage.
When the engine is running, the vehicle's power supply is provided by the vehicle's generator, which has a higher voltage than the battery (to recharge the latter). The voltage is higher and allows the ignition status to be determined.
The ignition detection by the movement sensor is convenient if the device is not connected to the vehicle's on-board electrical system. However, when the vehicle is towed, the ignition will also be detected as the vehicle moves, although the engine will not start.
The ignition source is selected from a drop-down list. If the ignition source is the on-board power supply voltage, the range of values in which the ignition is considered switched on must be selected.