DH Instruments PPC4, Operation And Maintenance Manual

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PPC4™ OPERATION AND MAINTENANCE MANUAL
© 2009 DH Instruments, a Fluke Company Page 50

OPERATION
For Basic Interface, see Section 4.5.5.5.
For Advanced Interface, see Section 5.7.7.5.
3.2.27 Internal Functions

PURPOSE
To view, set, adjust, and maintain various aspects of PPC4’s internal operation.
3.2.27.1 Identification

PURPOSE
To view or edit the PPC4 user ID and to view the PPC4 serial number.
Note
The ID can be set remotely from a computer which is more
convenient than entering characters from the keyboard (see
Section 6.5.4, ID command). The ID is not cleared or reset by
any RESET function (see Section 3.2.25).

OPERATION
For Basic Interface see Section 4.5.5.4.
For Advanced Interface see Section 5.7.12.1.
3.2.27.2 Control Reference

PURPOSE
To specify whether PPC4 should automatically determine whether a vacuum
source or atmospheric pressure is connected to its
EXHAUST port or to manually
set the EXHAUST port condition.

PRINCIPLE
The PPC4 exhaust (down) control valves and the output of the exhaust pressure
regulator are connected to the PPC4
EXHAUST port (see Figure 31).
The response of the pressure control module, particularly when controlling
pressure near and under atmospheric pressure, changes depending on whether
the
EXHAUST port is connected to a vacuum source or left open to atmosphere.
To use the proper pressure control algorithms, PPC4 must know the condition of
the
EXHAUST port.
The Control Reference function allows the PPC4 to know whether its EXHAUST
port is at vacuum or atmospheric pressure. An independent exhaust pressure
sensor measures the pressure present at the port. Normally, the exhaust sensor
output is used automatically by PPC4 to determine the
EXHAUST port condition.
If desired, this automatic determination can be overridden and the EXHAUST port
condition set manually.
The Control Reference function allows setting of whether the EXHAUST port
condition will be determined automatically using the exhaust sensor or set
manually. It also allows viewing of the current status of the
EXHAUST port.