WEG CFW500 V1.8X, Руководство по программированию, Страница: 115 / 172

Digital and Analog Inputs and Outputs
CFW500 | 12-9
12
12.3 FREQUENCY INPUT
A frequency input consists of a fast digital input able to convert the frequency of the pulses in the input into a
proportional signal with 10-bit resolution. After the conversion, this signal is used as an analog signal for speed
reference, process variable, use of SoftPLC, etc.
According to the block diagram of Figure 12.4 on page 12-9 , the signal in frequency is converted into a digital
quantity in 10 bits by means of the block “calc. Hz/%”, where parameters P0248 and P0250 define the input
signal frequency band, while parameter P0022 shows the frequency of the pulses in Hz. From this conversion
step, the signal in frequency receives a treatment similar to that of a regular analog input; compare to
Figure 12.2
on page 12-4 .
NOTE!
The frequency input signal at DI2 must be NPN regardless the setting in P0271 and it must not
exceed the limit of 20 kHz.
Function
FI – P0246
Gain
FI – P0247
Filter
P0245
100 (%)
FI(%)
FI(%) – P0021
FI(Hz) – P0022
FI(Hz)
Calc. Hz / %
(Hz)
P0248
P0250
OFFSET
FI – P0249
FI value
(internal)
FI signal
(NPN)
DI2 (*)
(*) Control terminal available in the plug-in module.
Figure 12.4:
Block diagram of frequency input – FI (DI2)
Digital input DI2 is pre-defined for frequency input with operating capacity in a wide band from 10 to 20.000 Hz.
The frequency input filter is the same as the one used for input AI3, that is, parameter P0245.
P0021 – Value of Frequency Input FI in %
Adjustable
Range:
-100.0 to 100.0 % Factory
Setting:
Properties: ro
Access Groups
via HMI:
READ, I/O
Description:
This read-only parameter indicates the value of the frequency input in percentage of full scale.
The indicated values are those obtained after the offset action and multiplication by the gain. Check the
description of parameters P0247 to P0250.