FMU125 Accessories

Please order accessories separately as they are not included into device package.

Accessory and its description	Accessory connection schematic
Fuel tank sensors	Fuel sensor connection to FMU125
A fuel tank level sensor that indicates the approximate fuel level on the driver's indicator panel exists in most cars. If the sensor returns an analog signal proportional to fuel level it can be connected to FMU125 Analog input. After connection to the tank fuel level sensor, a calibration is needed because most fuel tank sensors are not linear. Calibration is performed by measuring voltage values resulting from the volume of fuel in the tank.
Alarm buttons, door sensors etc.	Panic button connection to FMU125
Alarm buttons, door sensors, ignition, etc. have two output states: high or low. FMU125 Digital inputs are used to detect these states.
Relays	Inverting relay connection to FMU125
In cases when the sensor output signal is negative, an additional relay has to be installed to convert the negative signal to positive.
Immobilizer relay	Immobilizer relay connection to FMU125 output
When connected as shown on the right hand side, FMU125 disables engine starter when output is ON.
Automotive relay	Automotive relay pinout
An ordinary automotive relay is used to invert input signal or to immobilize engine starter. Note that relays can be 12 V or 24 V capable.
1-Wire devices	Digital thermometer DS1820 and TTJ100 connection to FMU125
One of the implemented features on FMU125 is 1-Wire® data protocol, which enables connection to devices such as thermometer (DS1820, DS18S20 and DS18B20) and I-Button DS1990A. Accessories that use 1-Wire Power and 1-Wire Data connections are not compatible with the FMB140, because it lacks a 1-Wire Power pin.
	TTJ sensor pinout
	I-Button DS1990A connection to FMU125