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input between plus and minus (ground GND) of the vehicle electrical system voltage (+9
... 30V).
If no change-over switch is available, an electric load for example, indicator light or
resistor, between the digital input and ground (GND) or between the digital input and the
vehicle voltage (+9 ... 30V) can offer defined levels.
When using inductive loads, a free-wheeling diode must be used in parallel with the load.