FMB125 Accessories

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Bw nb.png 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 FMB125
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 FMB125 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.
Sch fmb1yx lls.png
Alarm buttons, door sensors etc. Panic button connection to FMB125
Alarm buttons, door sensors, ignition, etc. have two output states: high or low. FMB125 Digital inputs are used to detect these states.
Sch fmb1yx panic.png
Relays Inverting relay connection to FMB125
In cases when the sensor output signal is negative, an additional relay has to be installed to convert the negative signal to positive.
Sch fmb1yx inv relay.png
Immobilizer relay Immobilizer relay connection to FMB125 output
When connected as shown on the right hand side, FMB125 disables engine starter when output is ON.
Sch fmb1yx imb relay.png
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.
Pic relay.png
Sch ord relay.png
1-Wire devices Digital thermometer DS1820 and TTJ100 connection to FMB125
One of the implemented features on FMB125 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.

Sch fmb125 ds1820.png
TTJ sensor pinout
Ttj pinout.png
I-Button DS1990A connection to FMB125
Sch fmb1yx ibutton.png