Siemens SIMATIC ET 200AL, System Manual

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High-speed analog modules
8.1 Basics
Analog value processing
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Function Manual, 06/2014, A5E03461439-AC
Typical applications
In principle, isochronous mode is worthwhile whenever measured values must be acquired
synchronously, movements must be coordinated, and process reactions must be defined
and executed at the same time. There are thus numerous areas in which isochronous mode
can be used.
Typical applications include, for example, the acquisition of binary signals for quality
assurance at specific times and positions. But hydraulic applications with position and
pressure control can benefit as well from the equidistant and isochronous data transmission.
The following example shows the use of isochronous mode within the production process of
camshafts. Precise measurements must be made at several measuring points for quality
assurance.
①
②
Measured values
Camshaft
Figure 8-5 Measuring of camshafts
By using the system property "isochronous mode" and the associated simultaneous
measured value acquisition, measurement can be performed continuously. The time
required for measurement is reduced. Resultant workflow:
●
Continuous machining of the camshaft
● During the continuous turning, measure the positions and cam excursion synchronously
● Process the next cam shaft
All camshaft positions and the corresponding measured values are measured synchronously
within a single rotation of the camshaft. This increases machine output and maintains or
enhances precision of the measurement.