18
Figure 9 I-Button DS1990A connection scheme
Fuel Tank sensors
A fuel tank level sensor exists in most cars, which shows the
approximate fuel level in the driver’s indicator panel. It is possible
to connect FM1100 Analog input to it (if sensor returns analogue
signal proportional to fuel level). Figure shows the connection
scheme to the FM1100 and fuel tank sensor. After the connection
to the tank fuel level sensor, calibration is needed. Calibration is
needed because most fuel tank sensors are not linear. Calibration
is performed by measuring voltage dependence on volume of fuel
in tank.
Alarm buttons, door sensors, etc.
Alarm buttons, door sensors, ignition, etc. return two states: high or low voltage. Digital
inputs are used to read this information. Figure below shows how to connect alarm button, door
sensor, etc.
Figure 11 Panic button connection
In cases when sensor output signal is negative, an additional relay has to be installed to
convert negative signal to positive.
Figure 10 Fuel sensor scheme
