Your Signals

The sensor being the first link of a measuring chain converts a physical measured quantity (e.g. pressure, distance, temperature) into an electrically measurable quantity (e.g. voltage, resistance). This is done by taking advantage of various electrical and / or physical effects.

The following information is provided to support you choosing a suitable sensor. Sensors are not available at bmcm. You will also find a selection of sensor manufacturers we recommend.

Indirect Measurements

You can only measure few quantities directly with DAQ systems (e.g. current, voltage). Therefore physical laws including a current or voltage relation are applied (indirect measurements).

A resistance measurement, for example, is done by connecting a resistor to a constant current source and measuring the voltage drop.
The resistance results from the division of the measured voltage through the applied current.

Sensor Adjustment

As you see, sensors "translate" physical into electrical quantities.

To connect them to a measuring system, the output must correspond in unit and range of values with the input of the DAQ device.

This is done by electrically transforming and / or amplifying the signal of the passive sensor with a measuring converter or amplifier.

Active Sensors

In many sensors, this electronic function is already included and they need their own power supply.

Those sensors are called active sensors, as they convert the measured quantity into a measurable electrical quantity themselves.

Physical Measured Quantities

Sensor symbols

The following list of sensor types exclusively applies to analog measured quantities, as we focus on analog measurement technology.

Measured Quantity Physical Phenomenon Sensor Type Comments, Examples
temperature temperature dependance of resistance PT100, PT1000, NTC, PTC nonlinear element
temperature Seebeck effect (thermoelectric voltage) thermocouple large measuring range, nonlinear element
temperature temperature dependance of semiconductors diodes, transistors also available as active sensor
temperature pyroelectric effect   for temperature change only
pressure, tension piezoelectric effect piezoelectric element for force and pressure changes only
pressure, tension, torque moment resistance dependance of the conductor shape strain gauge (DMS) usually connect as measuring bridge
position, length, angle, distance inductivity change of a coil when inserting a metal piece LVDT LVDT, differential choke measurement with carrier frequency procedure
position, length, angle, distance binary encoded angle and distance sensors angle encoder incremental or absolute; output digital
angle, distance linear potentiometer, rotary encoder potentiometer analog output signal
magnetic induction echo voltage with constant current echo sensor available as active integrated wiring
acceleration, velocity tension of metal plates in semiconductor component semicond. strain gauge uni- or multidimensional sensor
acceleration, velocity piezoelectric effect with a seismic mass piezoelectric element e.g. airbag sensor
luminous intensity photonic stimulation of semiconductors photodiode, phototransistor available as passive and active sensors
luminous intensity change of self-conductivity photoresistor  
current voltage drop at a resistor shunt galvanic connection to the meas. current
current measurement of the Hall echo sensor el.isolated from the meas. current
humidity semiconductors, capacitive sensors   passive elements
sound, sound level electrodynamic and capacitive microphones microphones  
filling-level capacitive and optical measurement   active sensors
rotational speed optical and inductive processes speed encoder digital and analog sensors
motion optical and inductive processes motion detector  

Sensor Manufacturers

The following table provides a small selection of sensor manufacturers. This is just a selection and does not imply any judgement.

Please note that we are not responsible for the contents of the linked sites and we do not check them regularly. In many cases, the mentioned semiconductor manufacturers do not have their own sales department.


Name Tension,
Gas Inductive, Echo Quality
ASM   x   x x     x high
AST x   x           high
Baumer x   x   x x   x high
B+B Sensors (HYGROSENS)       x         high
BCM Sensor x   x           high
BD Sensors x               high
B.I.O-Tech               x high
BLH (Vishay BLH)     x           high
Burster x x x   x     x high
disynet (German website) x x x   x       medium
E+E       x     x   high
electrotherm       x         high
Huba Control x   x           medium
Jumo x     x     x   high
Megatron     x   x       high
Messotron         x     x high
Micro-Epsilon         x x   x high
SEIKA   x             high
Sensitec         x     x medium
Sensor Technics x   x           high
TC Direct       x         medium
TWK         x x   x high
WIKA x     x         high