MKS T3PIA, Instruction Manual, Page: 54 / 70

Chapter Five: Maintenance and Troubleshooting Troubleshooting
46
Symptom Root Cause Correction
Poor pressure control—
oscillating. Tuning parameters are improper. If using PID Mode, optimize Gain and
Phase values (see
Phase and Gain , page
28).
If using Model Based mode, re-learn the
Pump Speed Curve (see
LEARN Function ,
page 26).
Ground connections have too high
impedance. Using MKS valve GUI, determine if
control offset is tuning or system ground
offset. Poor pressure control.
Indicated pressure is too
high or low (Control
offset).
Tuning parameters are improper. Tuning parameters need optimization.
Poor pressure control in a
specific pressure range. Crossover point not correct. Configure crossover pressure for installed
manometers.
Manometer not zeroed. Zero manometer. Valve reports negative
pressure.
Manometer does not have power. Verify power to manometer.
Manometer Full Scale setup not
correct. Valve reports unexpected
pressure.
Voltage range for manometer not
correct.
Configure valve for correct manometer
range (see the
MKS Type T3BIA/T3PIA
Valves with RS-232 Interface Supplement ).
Pump Speed Learn does
not work Manometer needs to be plugged in
high range for Pump Speed Learn
to be performed. Plug manometer in high range.
Communications
Symptom Root Cause Correction
Analog/TTL
communications fail. Incorrect settings or bad cable. Verify baud rate, data bits, parity, and CR-
LF.
Verify cable wiring.
DeviceNet
communications fail. Incorrect settings or lack of network
power. Verify MAC address and baud rate. Verify
network power.