3. OPERATION
Page 63
© 2009 DH Instruments, a Fluke Company
See Section 3.4.6 for information on customizing pressure control
parameters.
3.3.10.5
INTERRUPTING AUTOMATED PRESSURE CONTROL
Automated pressure control is interrupted by:
•
Pressing [ESC]:
Suspends control and remains in MAIN RUN screen.
Does not vent pressure. PPCH passively measures the pressure applied to
its
TEST
port. Pressure may take some time to stabilize if control mode is
dynamic as thermal pressure control unit stabilizes.
•
Pressing any direct pressure control key other than the jog keys (see
Section 3.1.3):
Suspends control and executes direct pressure control.
•
Pressing any function key:
Suspends control and goes to the selected
function. Does not vent pressure. PPCH passively measures the pressure.
•
Pressing [ENT/SET P]:
In dynamic, static and ramp modes
, suspends
control and goes to ENTER target screen. Does not vent pressure. PPCH
passively measures the pressure.
In monotonic mode
,
[ENT/SET P]
suspends control only if the pressure has not yet reached the target limit.
[ENT/SET P]
does not suspend control during the slow ramp after the target
pressure has been reached. This is to avoid suspending control when setting
the next pressure increment as that could cause the direction of pressure
evolution to reverse, violating the monotonic excursion.
•
Sending any remote command when in local mode
interrupts pressure
control.
To resume automated pressure control, press
[ENT/SET P]
and ENTER a target
pressure value.
3.3.10.6
AUTOMATED PRESSURE COMMANDS FOR ZERO PRESSURE
A command for automated pressure control to a target value of zero when in
gauge
or absolute measurement mode is interpreted in the same manner as if
the
[VENT]
direct pressure control key had been pressed (see Section
3.1.3).
A
Ready
condition occurs when the vent sequence has completed, including
running AutoZ, if applicable (see Section 3.5.1). Zero is not an accepted entry in
ramp control mode.
PPCH cannot set pressure under atmosphere. An automated pressure control
command for zero pressure in absolute measurement mode results in setting
atmospheric pressure by opening the TEST port to atmosphere. This is the lowest
absolute pressure PPCH can set. When zero absolute is given as a pressure target,
the pressure actually measured by the PPCH after the ready condition occurs must
be read back rather than assuming a specific pressure value has been set.
