Rockwell Automation 1771-QDC, D17716.5.86(Passport) PLASTIC MOLDING MODULE - Manual (Page 55)

Configure the QDC Module's I/O
Chapter 3
3-17
Configure Digital Filters for Position Inputs
You may enable an optional digital filter on position inputs to reduce
electrical noise from a potentiometer-type position sensors or picked up by
your input circuits.
To determine if you need a digital filter, move the ram (screw) or clamp
very slowly. With your programming terminal, look for erratic position
numbers reported for ram (screw) and/or clamp position by examining
these words:
For this Input: In Word: Look at this ProĆSet 600 Address:
Ram (Screw) SYS25 N40:177
Clamp SYS27 N40:179
Configure the QDC Module for a Digital Input Filter as Follows:
To determine the time constant (0 - 00.10 sec), start with a small value
such as 00.01. A value of zero disables the filter.
To Filter this Input: In Word: Enter a Filter Time Constant in:
Ram (Screw) MCC16 N40:12
Clamp MCC30 N40:26
ATTENTION: Increasing the value of the time constant
decreases the QDC module’s capability to respond quickly to
travel limits and/or to accurately locate programmed positions.
We recommend that you keep the time constant under 00.10.
For example, with a clamp velocity of 20”/sec, a 00.01 time constant
allows 0.20” of travel before the QDC module can react to a travel limit.
Important: If you have a noisy potentiometer-type position sensor and
digital filtering slows the QDC module’s response time too much, consider
replacing the sensor with a non-contact, linear-displacement type.
Download time constants to the QDC module using the procedures
presented earlier in this chapter.