130
6
chapitre
Acquisition de
données : détection
Présentation :
• Fonctions et des technologies de détection
• Tableau de choix
ter
Data acquisition:
etection
e
:
Detection features and technologies
Selection table
Summary
6 - Data acquisition:
detection
6.1
Introduction
132
6.2
Electromechanical limit switches
133
6.3
Inductive proximity detectors
134
6.4
Capacitive proximity detectors
136
6.5
Photoelectric detectors
138
6.6
Ultrasonic detectors
140
6.7
RFID -Radio Frequency IDentification-detection
142
6.8
Vision
145
6.9
Optical encoders
149
6.10 Pressure switches and vacuum switches
154
6.11 Conclusion
157
6.12 Technology selection guide
158
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M
6.1
Introduction
6 - Data acquisition:
detection
The field of data capture is divided into two families.The first, called detection,
comprises products that can detect a threshold or limit or estimate a physical
measurement.The second – measurement or instrumentation – measures a physical
measurement to a given level of accuracy.
In this section, we shall only describe sensors and detection devices for machines
and their related automation systems.
Sensors designed for machine safety are dealt with in appropriate section.
For those who are interested, there are many works on machine safety describing
all the devices available on the market.
These products have three essential functions as shown in the figure 1.
The diversity of these functions requires manufacturers to produce a great number
of product variants to cover all the requirements. Recent innovations in product
modulation enable Schneider Electric to offer smaller ranges with more versatile
applications.
6.1
Introduction
b Detection: an essential function
The “detection” function is essential because it is the first link in the data
chain (C Fig. 2) of an industrial process.
In an automatic system, detectors ensure that data is captured:
- on all the events needed for operation that are used by the control
systems according to a preset program;
- on the progress of al