Spectrum Controls 1756sc-CTR8 - Manual (Page 6)

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ControlLogix ™ Counter Module
1756 Series ControlLogix Module Installation Instructions
(Each module has separate document for installation)
1756-5.5,
-5.42
1756-L1, Logix5550 Controller User Manual 1756-6.5.12
-L1M1, -L1M2
1756-DHRIO ControlLogix Data Highway Plus
Communication Interface Module User Manual
1756-6.5.2
1756-ENET ControlLogix Ethernet Communication Interface
Module User Manual
1756-6.5.1
To obtain a copy of any of the Allen-Bradley documents listed, contact
your local Allen-Bradley office or distributor.
Terms &
Abbreviations You
Should Know
You should understand the following terms and abbreviations before using
this guide.
A/C - Refers to alternating current. This is a sine wave signal that is
typically associated with magentic pickup flowmeters.
Attenuation – The reduction in magnitude of a signal as it passes through
a system. The opposite of gain.
Channel – Refers to one of eight, small-signal analog input interfaces to
the module’s terminal block. Each channel is configured for connection to
a input device, and has its own configuration and status words.
Chassis – See rack.
Common mode rejection ratio (CMRR) - The ratio of a device’s
differential voltage gain to common mode voltage gain. Expressed in dB,
CMRR is a comparative measure of a device’s ability to reject
interference caused by a voltage common to its terminal relative to
ground.
Common mode voltage – The voltage difference between the negative
terminal and analog common during normal differential operation.
Cut-off frequency - The frequency at which the input signal is attenuated
3 dB by the digital filter. Frequency components of the input signal that
are below the cut-off frequency are passed with under 3 dB of attenuation
for low-pass filters.