Rockwell Automation 1771-QDC, D17716.5.93(Passport) PLASTIC MOLDING MODULE - Manual (Page 247)

Tune Your Machine
Chapter 10
10-19
Profile Watchdog Timer and Profile Offsets
Profile Watchdog Timer
(PLC08)
Set your plastication profile watchdog timer preset after your machine is
running repeatable, quality parts. Set it just longer than the repetitive
duration of the profile to warn that a process problem may be developing.
For example, warn of a low feed level from the hopper.
Profile Offsets
(for velocity – IPC51)
(for pressure – IPC52, HPC25 and 42, PPC52)
The offset shifts the amplitude of all pressure or velocity setpoints (y-axis)
of a profile by a single value. Use it during set-up after you have obtained
the desired profile shape to boost or reduce the overall effect of the profile.
Pressure Alarm Setpoints
The QDC monitors process pressure and compares it against two different
types of high pressure alarm setpoints. Pressure is compared to the
absolute pressure alarm setpoint (configured in the MCC - refer to chapter
4) on a continuous basis and without regard to current machine mode or
operational cycle. Pressure is compared to profile pressure alarm setpoints
(configured in the respective configuration blocks - refer to chapter 7) only
during the execution of the subject profile. In general:
Use the absolute pressure alarm to detect dangerously high pressure
conditions. We recommend that you set this alarm setpoint well above
normal operating levels while still below levels that could result in
machinery damage or danger to personnel. Program your PLC-5 ladder
logic to stop the QDC module and place the machine in a safe condition
if this alarm is triggered.
Use profile pressure alarms to detect abnormally high pressure
conditions. We recommend these alarm setpoints be set only marginally
above the highest pressure expected during any acceptable iteration of
the subject profile while still low enough to be indicative of process
problems. Program your PLC-5 ladder logic to interrupt the process or
signal the machine operator to determine corrective action if one of
these alarms is triggered.