3. OPERATION
Page 17 © 1998 DH Instruments, Inc.
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3.1 GENERAL/MANUAL OPERATION
PPC2 AF is designed to offer a balance between simple, straight forward operation and the
availability of a wide variety of functions with a high level of operator discretion if desired. The local
operator interface is through a 2 X 20 display, a 4 X 4 keypad and 4 direct pressure control keys.
3.1.1 THE MAIN RUN SCREEN
The PPC2 AF main run screen is its home display that is reached on power up and from
which other functions and menus are accessed. It is the very top level of all menu structures.
The main run screen is where the operator works with PPC2 AF to set and read pressures.
It provides complete information on the system's current configuration and operating status.
1. * Ready/Not Ready indication (See Section 3.1.2.4).
* when Ready,
or indication direction of pressure evolution
if Not Ready.
2. PRESSURE1: Numerical value and sign of pressure
currently measured by currently active transducer and range.
3. UNIT: Current unit of measure of pressure indication
(see Section 3.2.2).
4. M: Pressure measurement mode: g for gauge, a for
absolute (see Section 3.2.2).
5. H: Indicates if a head correction is applied. H if applied,
blank if not (see Section 3.2.7).
*PRESSURE1 UNITMH SR
TPRESSURE2 CC NN/NN
6. SR: Indicates active reference transducer (H for high, L for low) and range (1 = low, 2 = mid, 3 = hi)
(see Section 3.2.1).
7. T: Indicates whether number following is target pressure (T), rate of change of pressure (R) or deviation
from target value (D) (see Section 3.2.3).
• Target pressure (T) will be indicated when:
- Dynamic control is active and pressure is NOT READY.
- Static control is active and valves are operating.
• Deviation (D) will be indicated when:
- Dynamic control is active and pressure is READY.
• Rate of change (R) will be indicated when:
- No control is active, i.e. control is suspended or
system is vented.
- Static control is active, and no valves are active.
8. PRESSURE2: Numerical sign and value of either target pressure, rate of change of pressure or deviation
from target. Target value and deviation in the same pressure unit as the current unit in 3. above. Rate of
change of pressure is in current unit per second (see Section 3.2.3).
9. CC: Pressure control mode (S for static, D for dynamic) with a (C) appended if custom control settings are
in use. These characters flash when the system is controlling. In static mode, if control is active they flash
even if no valve is operating, for example while inside the hold limit and waiting for stability. Characters flash
while controlling pressure down to vent but not when vent valve is open (see Sections 3.2.3 and 3.2.6).
10. NN/NN: Used only when running a sequence. Indicates number of increment currently being worked on
over total number of increments in the sequence or enter when “ready”. Changes to a countdown time during
count down when next increment of sequence is on timed delay rather than enter.
PPC2 AF has a screen saver function which causes the display to dim if no key is pressed
for 10 minutes. Pressing a key restores full power to the display.
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