Measurement Modes; Overview - Siemens SIMATIC ET 200S Operating Instructions Manual

1Count5V/500kHz

3.7 Measurement Modes

3.7 Measurement Modes
3.7.1

Overview

Introduction
Select your mode from the "Measurement Modes" parameter
• Frequency Measurement
• Period Measurement
• Rotational Speed Measurement
and choose a measuring method from the "Measuring Methods" parameter:
• with integration time
• continuous
To execute one of these modes, you have to assign parameters to the 1Count5V/500kHz.
Measurement Process
The measurement is carried out during the parameter assignment integration time. When the
integration time elapses, the measured value is updated.
The end of a measurement is indicated by the STS_CMP1 status bit. This bit is reset by the
RES_STS control bit at the control interface.
If there were not at least two rising edges in the integration time which has been assigned
parameters, 0 is returned as the measured value.
A value of -1 is returned by the end of the first integration time.
You can change the integration time for the next measurement during operation.
Reversal of the direction of rotation
If the direction of rotation is reversed during an integration time, the measured value for this
measurement period is uncertain. If you evaluate the STS_C_UP and STS_C_DN feedback
bits (direction evaluation), you can respond to any process irregularities.
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Technological Functions
Operating Instructions, 02/2007, A5E00124867-05