Watlow CLS - Manual (Page 85)

Setup
CLS User’s Guide 77
Input Filter
The CLS 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 CLS 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 accep-
tance band, the CLS accepts the anomalous reading and calculates a
new acceptance band. (You cannot adjust this input filter.)
• 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 CLS
scans each input loop 6 times per second. The input filter applies to all
input types except those set to SKIP.
Selectable range: 0-255 scans. 0 disables the filter.
LOOP PROCESS UNITS
ALARM SETPOINT STATUS OUT%
01 INPUT FILTER ?
3 SCANS