SENSORS
Magnetic sensor encoding

SeriesSL

1C

225-GSLSC/SS /SN/SA/SM/CB/PRO-SS/PRO-SN/SSYConnection
1234567892-pole cable
2-pole M8 connector
3-pole M8 connector
3-pole cable
2-pole M12 connector
3-pole M12 connector
3-pole M12 connector
3-pole AU M8 connector
3-pole AU M12 connector

Circuit type
A
B
C
DEF
GHL
M
NPS
V

NO LED 2-wire reed
NO LED + VDR 2-wire reed
2-wire reed
3-wire PNP reed
2-wire magnetoresistive (PNP-NPN)
NO LED 2-wire NC reed
NO LED + VDR 2-wire NC reed
2-wire NC reed
Magnetoresistive NPN
Magnetoresistive PNP
Magnetoresistive PNP NC
Magnetoresistive NPN NC
Changeover reed
0-10V analog

12455V dc
24 V ac/dc
110 V ac/dc
250 V ac/dc

...
03
250m
0.3 m
2.5 m-G

Gimatic S.r.l

Power supply voltage

Standard cable length

01/2021

Personalization

912

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SENSORS
All other sensor encoding
SISeries

4N

225-GSISIS /SO /SOQ /SUConnection
4893-wire cable
AU M8 connector
AU M12 connector

Circuit typeMN

Magnetoresistive NPNMagnetoresistive PNP

Rated voltage
224 V dc

Cable Length...
03250m
0.3 m
2.5 m

Personalization-G

Gimatic S.r.l

Connector encodingSeries

CFG

M8 00

325PCF

TypeG
S

Metal ring nut
SnapThread
M8
M12

M8x1
M12x1

Angle
00
900°
90°

Number of poles
234

Cable length

01/2021

00
2530
50
1k...
P
www.gimatic.com

no cable
2.5 m
3m
5m
10 m

Cable material
PVC
PUR

913

SENSORS
General features
Magnetic sensors are devices that change circuit output status
in the presence of magnetic fields. They are normally used as
proximity sensors on cylinders with a permanent magnet in thepiston. By positioning the sensor in a special housing on theoutside of the cylinder body, the position of the piston can bedetected via an electric contact or voltage signal. The sensing
element may be a reed switch or magneto resistive chip (GMRsensor) depending on the type of sensor. Sensors are available
with a cable outlet or connector. A bespoke service is available
if our standard products do not meet customer requirements.

Choosing a sensor
A sensor is a switch that is usually connected in series toa cable, therefore it must be installed in line with specified
electrical characteristics.
There are two principles of operation:a REED SWITCH where the sensing element consists ofa glass bulb containing two polarised metal strips. Thereis an attraction between these strips in the presence of amagnetic field. It can operate with a DC or AC voltage supply.
The sensing element could malfunction in the presence ofstrong vibrations.
ELECTRONICALLY where the sensing element is amagnetoresistive chip (GMR sensor), which changes thestatus of an output in the presence of magnetic fields. It onlyoperates with a DC voltage supply and has a theoreticallyinfinite lifetime. The sensing element is immune to strong
vibrations.

••01/2021

The decision to choose a PNP or NPN output is usually
determined by the method of integration in the existing
automation system: for correct system operation, the typeof sensor output must correspond to the type of controller(or PLC) output used. The PNP solution is generally morewidespread in North America and Europe, whereas the NPN
solution is more common in Asia. PNP sensors are vulnerable
to short circuits, whereas NPN sensors can produce false
signals in the controller in the event of an unwanted earth
contact. A final consideration is the status of the sensor underactive conditions, i.e. between a normally open (NO) or normallyclosed (NC) sensor. In the first case the sensor behavesaccording to positive sensing logic, a signal is not generated if
a wire is interrupted but false signals may be produced in theevent of a short circuit. In the second case the sensor behavesaccording to negative sensing logic, and an interrupted wire
would produce a false signal. The logic can easily be inverted inboth cases by the controller (or PLC).

914

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SENSORS
Instructions on using magnetic sensors
Magnetic sensors are often used in combination with magnets
to produce magnetic actuation, and are typically embeddedin actuators. The main characteristic of any digital magnetic
sensor is the sensitivity level representing the magnetic fieldstrength value at which the sensor switches the output. The
graph below shows the typical waveform of axial magnetic fieldstrength measured by a Gauss meter in the central position(PC). Depending on the sensitivity level of the sensor andmagnetic field characteristics, a sensor placed centrally may
switch output several times during the actuator stroke. Unlessstated otherwise, it is generally good practice not to install thesensor centrally, but to insert it laterally into the groove andmanually adjust the position of the sensor while performing
several actuator strokes.
In practice, sensors are normally only used to identify end-ofstroke conditions.
For any other operating conditions, please contact the technicalsupport department.

Switching points of a sensor in central position
Axial magnetic field strengthSensor sensitivity threshold

StrokeSensor slot

Displacement

Central position (not recommended)

Magnetic sensor

Magnetic sensor
S N

Embedded magnetActuator

Sensor safety circuit
The switching of inductive loads with reed switches produces
a high voltage peak during disconnection. As a result, a safety
circuit is required to prevent dielectric discharges or voltaic
arcs. This can be:
A R-C circuit in parallel with the load in the case of a DC
voltage supply (figure 1).
A diode in parallel with the load in the case of a DC voltage
supply (figure 2).
2 Zener diodes in parallel with the load with an AC/DC
voltage supply (figure 3).
A varistor (VDR) in parallel with the load with an AC/DC
voltage supply ( figure 4).

••••

01/2021

The switching of capacitive loads or the use of cables longer
than 10 metres produces current peaks during connection.
As a result, protective resistance is required near the switch
on the brown wire. In this phase ensure the minimum current
required for the sensor is guaranteed (10÷20 mA).

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