Watlow MLS-PM, User Manual

Page: 89 / 144

76 MLS User’s Guide
Setup
Input Filter
Access this menu from the Setup Loop Inputs main menu. The MLS has
two different types of input filter:
• A noise rejection filter that rejects high frequency input signal noise.
This filter keeps a "trend log" of input readings. If a reading is out-
side the filter's "acceptance band", and later readings are within the
acceptance band, the MLS ignores the anomalous reading. (The
acceptance band for thermocouples is 5 degrees above and 5
degrees below the input reading. For linear inputs, it's 0.5% above
and 0.5% below the input reading.) If later readings are also outside
the acceptance band, the MLS accepts the anomalous reading and
calculates a new acceptance band. (This input filter does not require
adjustment.)
• A standard resistor-capacitor (RC) filter that lets you dampen the
input response if inputs change unrealistically or change faster than
the system can respond. If the input filter is enabled, the process
variable responds to a step change by going to 2/3 of the actual
value within the number of scans you set.
If all input loops are enabled (none of them are set to SKIP) the MLS
scans each input loop 2 times per second. The input filter applies to all
input types except those set to SKIP.
Selectable range: 0-255 scans.
LOOP PROCESS UNITS
ALARM SETPOINT STATUS OUT%
01 LOW PASS FILTER
VALUE? 3 SCANS