Spectrum Controls 140 EHC 204 00sc - Manual (Page 72)

Counter / Flow Meter Input Module
73
Glossary
The following terms and abbreviations are used throughout this manual.
A/D converter – The analog-to-digital converter used in the module. The converter produces a digital value
with a magnitude that is proportional to the magnitude of an analog input signal.
attenuation – Reduction in the magnitude of a signal as it passes through a system.
bus connector – A 16-pin male and female connector that provides electrical interconnection among modules in
a controller system.
channel – Analog input interface available on the terminal block of a module. Each channel is configured for
connection to an input device, and has its own configuration and image input data words.
channel update time – The time required for the module to sample and convert the input signals of one
enabled input channel and update the data word.
common mode voltage – Voltage difference between the negative terminal and analog common during normal
differential operation.
common mode voltage range – For analog inputs, the largest voltage difference allowed between either the
positive or negative terminal and analog common during normal differential operation.
configuration word – Word containing the channel configuration information needed by the module to set up
and operate each channel.
cutoff frequency – The frequency at which the input signal is attenuated 3 dB by a digital filter. Frequency
components of the input signal that are below the cutoff frequency are passed with under 3 dB of attenuation
for low-pass filters.
data word – A 16-bit integer that represents the value of an input channel. The data word is valid only when the
channel is enabled and there are no channel errors. When the channel is disabled, the channel data word is
cleared (set to 0).
digital filter – A low-pass noise filter incorporated into an A/D converter. The filter provides high-rejection
notches at frequencies that are integral multiples of the filter cutoff frequency. The notches are used for rejecting
AC power line noise and higher frequency noise.
effective resolution – The number of bits in a channel configuration word that do not vary due to noise.
filter frequency – User-selectable frequency for a digital filter.
full scale – The magnitude of input over which normal operation is permitted.
gain drift – Change in full-scale transition voltage measured over the operating temperature range of the module.