Spectrum Controls 1756-CTR8, User Manual

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6-4 Chapter 6: Programming Examples
Owner’s Guide 0300199-01 Rev. D
points, a start and a stop. A pulse trigger caused by a ball crossing a proximity
switch zeros the counter and starts the accumulation. When the ball reaches the
end of the run, another pulse occurs stopping and storing the accumulated value.
If the input device is an open collector type it may be necessary to use a pull-up
or pull-down resistor in order to achieve the proper threshold crossover point. We
recommend a 1 Kohm, resistor and tying it between the input path and ground to
pull down or the input path and a +12/24 V source for pull up.
Use of digital filters will ensure the best possible performance.
Recommendations are as follows:
Maximum Signal Input Filter
65 kHz No filtering
25 kHz 25 kHz digital filter
12 kHz 25 kHz and 12 kHz filters
The debounce filter is best used when the gate input is connected to low-
frequency input devices such as relays or proximity switches. These devices do
not typically have any on-board debounce circuitry.
The 1756sc-CTR8 module provides a feature that allows you to perform meter
proving functions. A typical meter proving application would include two
detector sensors that are located a fixed distance from each other within a section
of pipe used specifically for meter proving.
The operation does not disrupt the in-situ flowmeter’s operation.