Usage for Time and Frequency Measurement

The time and frequency measurement functionality of the DC541-CM is provided by the block DC541_FREQ: DC541_FREQ DC541_FREQ.

The inputs and outputs of the block DC541_FREQ are described in detail in the documentation of the library DC541_AC500_V11.LIB.

The Function Block DC541_FREQ is used to measure times, frequencies and rotational speeds with a resolution of 100 µs.

It is able to measure frequencies from 0 to 2000 Hz (2 kHz). In order to obtain a precise measurement of frequencies > 50 Hz, a correspondingly high accuracy setting has to be chosen. It is recommended to use an accuracy of PREC = 1000, i.e. 0.001.

This Function Block has to be called cyclically, one time per second at least.

The inputs EN_0, EN_1 and EN_FREQ are used to determine the edges to be measured. If input EN_FREQ = TRUE, the frequency and the rotational speed are calculated in addition to the time measurement.

• Configuration Example: Frequency Output