Rockwell Automation 2085 Micro800 Discrete and Analog Expansion I/O Modules - Manual (Page 22)

14 Rockwell Automation Publication 2080-UM003A-EN-E - March 2013
Chapter 2 Discrete and Analog Expansion I/O Features
Temperature Units
Temperature value can be set to °C (default) or °F.
Open circuit response
This parameter defines the response to be taken by the module during an open
circuit.
• Upscale – Sets input to full upper scale value of channel data word. The
full-scale value is determined by the selected input type, data format, and
scaling.
• Downscale – Sets input to full lower scale value of channel data word. The
low scale value is determined by the selected input type, data format, and
scaling.
• Hold Last State – Sets input to last input value.
• Zero – Sets input to 0 to force the channel data word to 0.
Filter frequency
The 2085-IRT4 module uses a digital filter that provides noise rejection for the
input signals. The filter is set by default at 4 Hz. The digital filter provides
-3 dB (50% amplitude) attenuation at a filter frequency of 4 Hz.
The -3 dB frequency is the filter cut-off frequency. The cut-off frequency is
defined as the point on the frequency response curve where frequency
components of the input signal are passed with 3 dB of attenuation. All input
frequency components at or below the cut-off frequency are passed by the digital
filter with less than 3 dB of attenuation. All frequency components above the
cutoff frequency are increasingly attenuated.
The cut-off frequency for each channel is defined by its filter frequency selection
and is equal to the filter frequency setting. Choose a filter frequency so that your
fastest changing signal is below that of the filter’s cut-off frequency. The cut-off
frequency should not be confused with the update time. The cut-off frequency
relates to how the digital filter attenuates frequency components of the input
signal. The update time defines the rate at which an input channel is scanned and
its channel data word is updated.
A lower filter frequency provides a better noise rejection, but it also increases the
update time. Conversely, a higher filter frequency provides a faster update time,
but it decreases the noise rejection and effective resolution.
Summary This chapter discussed the features of the analog and discrete Micro800
expansion I/O modules.
TIP For quickstart instructions on how to add, configure, delete and replace
your expansion I/O module, see
Configure Your Expansion I/O Module .