Span Your Valves
Chapter 9
9-24
What You Have Accomplished
The open-loop tuning procedure you just completed has defined the:
range of ram (screw) backpressure during plastication
end-of-range maximum and minimum signal levels for linear control of
the plastication pressure valve in open-loop control
For this
range limit
When trying to obtain
the pressure in:
The QDC module drives the selected
pressure valve to % output signal in:
Minimum
PLC41
PLC43
Maximum
PLC42
PLC44
Now for open-loop plastication profiles, the QDC module assumes a liner
relationship between backpressure and signal output.
Set the Profile Pressure Alarm
After spanning your plastication pressure valve, set the maximum pressure
alarm setpoint PLC57 (N44:413) equal to a ram (screw) backpressure that
should not be exceeded during the plastication profile. Make sure this
value is not greater than PLC42 (N44:398) Maximum Pressure Control
Limit. Entering zero disables this alarm.
Download the PLC and PPC blocks to the QDC module.
Important: If downloading from your programming terminal, you must
download PLC first, followed by PPC.
To download
Set
PLC
B21/13
PPC
B21/14