Analog Value Processing; Conversion Method; C.1 Conversion Method - Siemens Simatic S7-1500 Manual

Analog value processing

C.1

Conversion method

Conversion
An integrated analog-to-digital converter converts the analog signal into a digital signal in
order that the compact CPU can process the analog signal read in by an analog channel.
Once the CPU has processed the digital signal, an integrated digital-to-analog converter
converts the output signal into an analog current or voltage value.
Interference frequency suppression
The interference frequency suppression of the analog inputs suppresses the interference
caused by the frequency of the AC voltage network used. The frequency of the AC voltage
network may interfere with measured values, particularly for measurements within narrow
voltage ranges.
You set the line frequency with which the plant operates (400, 60, 50 or 10 Hz) using the
"Interference frequency suppression" parameter in STEP 7 (TIA Portal). The "Interference
frequency suppression" parameter can only be set module-wide (for all input channels). The
interference frequency suppression filters out the set interference frequency
(400/60/50/10 Hz) as well as multiples of it. The selected interference frequency suppression
also defines the integration time. The conversion time changes depending on the set
interference frequency suppression.
For example, an interference frequency suppression of 50 Hz corresponds to an integration
time of 20 ms. The analog on-board I/O supplies one measured value to the CPU every
millisecond over a period of 20 ms. This measured value corresponds to the floating mean
value of the last 20 measurements.
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CPU 1512C-1 PN (6ES7512-1CK00-0AB0)
Manual, 09/2016, A5E35306440-AB
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