Rockwell Automation 2085 Micro800 Discrete and Analog Expansion I/O Modules - Manual (Page 18)

10 Rockwell Automation Publication 2080-UM003A-EN-E - March 2013
Chapter 2 Discrete and Analog Expansion I/O Features
• 4-Point Moving Average
• 8-Point Moving Average
Noise Rejection
The input modules use a digital filter that provides noise rejection for the input
signals.
The moving average filter reduces the high frequencies and random white noise
while keeping an optimal step response. (See specifications for
Analog Expansion
I/O on page 50 for minimum and maximum response times.)
Normal Mode Rejection is better than 40 dB, while Common Mode Rejection is
better than 60 dB @ 50/60 Hz, with the 50/60 Hz rejection filters selected. The
modules perform well in the presence of common mode noise as long as the
signals applied to the user plus and minus input terminals do not exceed the
common mode voltage rating (±10 V) of the modules. Improper earth ground
may be a source of common mode noise.
Process Level Alarms
Process level alarms alert you when the module has exceeded configured high and
low limits for each channel (for input modules, it provides additional high-high
and low-low alarms). When the channel input or output goes below a low alarm
or above a high alarm, a bit is set in the status words. All Alarm Status bits can be
read individually or read through the Channel Status Byte.
For the output module, 2085-OF4, it is possible to latch the alarm status bit
when the latch configuration is enabled.
You can configure each channel alarm individually.
Clamping Limits and Alarm
For the output module, 2085-OF4, clamping limits the output from the analog
module to remain within a range configured by the controller, even when the
controller commands an output outside that range. This safety feature sets a high
clamp and a low clamp. Once clamps are determined for a module, any data
received from the controller that exceeds those clamps transitions the output to
that limit but not beyond the clamp value. It also sets the alarm status bit when
the alarm is enabled. It is also possible to latch the alarm status bit when the latch
configuration is enabled.
For example, an application may set the high clamp on a module for 8V and the
low clamp for -8V. If a controller sends a value corresponding to 9V to the
module, the module will only apply 8V to its screw terminals.
You can configure the clamp limit (high/low clamp), the associated alarm, and its
latching configuration on a per channel basis.