3. OPERATION
Page 49 © 2002-2007 DH Instruments, a Fluke Company
Due to the manner in which PPC3 handles an automated pressure command for zero in
absolute pressure measurement mode, a Ready condition can occur at a pressure well
outside of the hold limit. When setting zero in absolute measurement mode, the Ready
condition should NOT be interpreted as meaning that the pressure is zero within the hold
limit. Ready is an indication that the rate of change of pressure inside PPC3 has reached the
current stability limit. The current pressure measured by PPC3, not zero, should be used as
the value of pressure applied to the device or system under test.
When PPC3 is given a command to set zero in absolute measurement mode, the rate of
change of pressure will decrease as the pressure decreases and the rate will eventually be
near zero when the vacuum pump has pulled down the pressure in the PPC3 and the test
volume as far as possible. To make best use of the Ready/Not Ready indication when
setting zero in absolute measurement mode, set the stability limit (see Section 3.4.6.1)
to a value that represents the rate of change of pressure expected when the vacuum
pump connected to the EXHAUST port has reduced pressure as far as possible.
3.4 [SETUP]
PURPOSE
[SETUP] accesses a menu of functions and features commonly used in setting up and using PPC3.
OPERATION
To access the SETUP menu, press [SETUP] from the MAIN RUN
screen. The display is:
1range 2res 3jog 4UL
5ATest 6control 7drv
SETUP menu choices include:
<1range> Save and delete ranges created by AutoRange (see Section 3.4.1).
<2res> Adjust the resolution of pressure displays (see Section 3.4.2).
<3jog> Adjust the jog function pressure step value (see Section 3.4.3).
<4UL> Adjust upper and lower pressure setting limits (see Section 3.4.4).
<5ATest> View data files resulting from running QDUT AutoTests (See Section 3.4.5).
<6control> Select pressure control mode and view/adjust control limits (See section 3.4.6).
<7drv> Set and view status of external 12V drivers (see Section 3.4.7).
3.4.1 <1RANGE>
PURPOSE
Save AutoRange ranges and associated settings for recall. Delete previously saved
AutoRange ranges.
PRINCIPLE
The PPC3 AutoRange function creates a range and automatically sets various operating
parameters proportionally to the range (see Section 3.3.4). Operating settings can then be
changed by the user. Many operating settings are specific to the current range (see Table 4).
[SPECIAL], <1range> allows the AutoRange range and associated settings to be saved for
later recall using the [RANGE] key (see Section 3.3.1). This can save the user from having
to recreate frequently used ranges and custom settings.
[SPECIAL], <1range> is also used to delete ranges that have been saved but are no longer needed.
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