Contemporary Control Systems BAScontrol20 Installation Guide - Manual (Page 9)

TD100700-0IA
9
Universal Input — Configured for Pulse Input
Assuming a 50% duty cycle, a pulse rate up to 40 Hz can be measured on
channels UI1–UI4. With a web browser, access the Main Screen, click the
title link of the selected channel. Set the Channel Type to Pulse Input and
the desired accumulated Units to NO_UNITS or the proper units for the
accumulated counts. The device can have an active output or passive
output. Data is an accumulated pulse count.
When using a passive output pulse device, enable Pull Up Resistor in the
web page configuration for the channel. When using pulse outputs with an
active output, disable Pull Up Resistor.
The Pulse Input voltage low-threshold and high-threshold are adjustable.
The difference in the two thresholds is the hysteresis. Sinusoidal signals
can be detected if within the threshold
limits. Any substantial swing within
this range can be detected. The input
impedance using Pulse Input is 1 MΩ
if the pull-up is not enabled. Connect
the output of the pulse device to point
A and the common to BASC20
common as shown in Figure 7.
The pulse output could be sinusoidal
with no DC offset so the BASC20
could experience both positive and
negative excursions of the signal.
The BASC20 can only detect positive voltages so the negative
excursions will be ignored. It is still possible to detect the input signal
by only sensing the positive excursions.
When interfacing to a pulse device that has an opto-isolated open-collector
output,
the internal pull-up resistor must be enabled on the device by selecting
this option in the web page . In Figure 7 , a three-phase wattmeter has three
opto-isolated open-collector outputs, each requiring the internal pull-up
resistor to be enabled.
Figure 7 — Pulse Input Connection