Sutron Xpert2, Руководство по эксплуатации и обслуживанию

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Frequency (Freq)
Inputs
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Outputs
Freq
Wiring
Connect the sensor frequency output to the selected CH1..CH8 of the digital module.
Connect the sensor GND to GND.
Description
This block outputs the frequency of a digital input signal. First, select the Digital I/O Module and
the channel number. Channels have a maximum frequency of 1KHz. The field
Multiplier is
normally left at one unless the cycles-per-second output of the frequency is to be changed. For
example, to changing to cycles-per-minute, enter 0.0167 for this field.
The Period mostly has to do with when the block takes instantaneous (as opposed to continuous)
frequency readings. For instantaneous readings, the Frequency block takes two time/count
readings from the I/O module at
Period time apart and used these to calculate the frequency of
the signal. The longer the value entered for Period the greater the accuracy of the frequency
(because of averaging) but the less “instantaneous” the reading with be.
When the frequency is being sampled frequently by a Measure or Average block, it might make
sense to only take one time/count reading from the I/O module every pass, and calculate the
frequency from the current and previous readings. For a sampling interval of 1 second, this
would be the same as having the
Period set to 1,000. If this is desired, un-check Take Two
Readings at a Time, and set Period to 1,000. The Xpert will use the previous reading as long as it
was taken within the time range of Period +/- Period /4 of the current time. Be careful how you
set Period when Take Two Readings is unchecked. The smaller you make Period , the more
likely the system will still take two measurements even though Take Two Readings is not
checked. You should not make Period longer than the sampling interval of your measure or
average block, or you will slow down data to the block. If you always want to use the previous
reading to compute the frequency regardless of when it was measured, use the COUNTER block.
The block scales the outputs according to the values of Slope and Offset using the equation
output = reading*slope+offset.
The user can change the units for all the outputs by changing the Units field to the desired value.
The block supports calibration from the Sensors page. For the calibration, the user will enter the
current value. The system will then adjust the offset so the desired value is obtained.