Siemens Simatic S7-300 Instrukcja Obsługi Pobierz pdf (Strona 303)

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Principles of analog modules

5.5 Conversion and cycle times of analog modules

S7-300 Module data

Manual, 02/2013, A5E00105505-08

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Example

Two analog input channels of the SM 331; AI 2 x 12 Bit analog input module form a channel

group. You must therefore grade the cycle time in steps of 2.

Setting smoothing of analog values

Certain analog input modules allow you to set smoothing of analog values in

STEP 7

Using smoothing

Smoothed analog values provide a reliable analog signal for further processing.

It is useful to smooth the analog values with slow variations of measured values, for

example, when measuring temperature.

Smoothing principle

The measured values are smoothed by digital filtering. Smoothing is accomplished by the

module calculating mean values, derived from a defined number of converted (digitized)

analog values.

The user configures up to four grades of smoothing (none, low, average, high). The grade

determines the number of analog signals used for averaging.

A higher smoothing provides a more reliable analog value, and prolongs the time it takes to

apply a smoothed analog signal following a step response (see the example below.)

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