Supply voltage Uc
Voltage range required by the switch to maintain its proper function.

Nominal voltage Un
The supply voltage value at which all the other parameters are defined.

Supply current Ic
The current consumed by the switch from a power supply at the nominal voltage and the ambient temperature of 20 °C. It is the switch intrinsic consumption and does not include the current intensity flowing through the switch output.

Output current Iz
The current that can be taken from the output. If the switch is short-circuit proof, the output current value can double at short-circuit.

Nominal sensing distance Sn
An electrically conductive object can approach the active switching zone in the axial (direction of the axis) or in the lateral direction (perpendicular to the switch axis). The nominal sensing distance is the distance between the switch active face and the axially approaching conductive object at which the output state changes. It is defined at the nominal voltage and the ambient temperature of 20 °C by using a 1mm thick target of 11370 grade steel with the surface equal the switch active face.

Effective sensing distance Sr
Considering the tolerance of the components used for the switch manufacture, the sensing distance values differ and are delimited by the effective sensing distance.

Hysteresis Sa
The difference between the operate (switch on) and release (switch off) point is called hysteresis. It is defined in the axial direction, at the nominal voltage and the ambient temperature of 20 °C.
Figure No.1 gives the trigger curves and the hysteresis of the PSI 126 311 switch. Other switch type curves are almost identical; they differ only quantitatively.

Switching frequency f_T
This frequency indicates the maximum number of switching operations per second. Figure No.2 shows method of determining the maximum switching frequency.

Operating temperature Ta
It is the ambient temperature range at which the reliable switch function is warranted.

Switch connection
The output device is NPN or PNP transistor.