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

3.7

Measurement Modes

3.7.1

Overview

Introduction
For the "Measuring Mode" parameter, you can select from the following modes:
● Frequency Measurement
● Period Measurement
● Rotational Speed Measurement
For the "Measuring Method" parameter, you can select from the measurement methods:
● With integration time
● Continuous
To run one of these modes, you have to assign parameters to the 1Count5V (see section
"Parameter Assignment for Measurement Modes (Page 195)").
Sequence of Measurements with Integration Time
The measurement is carried out during the assigned 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 in the control interface.
If there were not at least two positive edges in the integration time which has been assigned
parameters, 0 is returned as the measured value.
A value of -1 is returned up until the end of the first integration time.
You can change the integration time for the next measurement during operation.
Direction Reversal
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.
Technological Functions
Operating Instructions, 06/2010, A5E00124867-07
1Count5V
3.7 Measurement Modes
165