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RPM4™ OPERATION AND MAINTENANCE MANUAL
© 2004-2007 DH Instruments, a Fluke Company Page 48
3.3.9.2 [AUTOZ] IN ABSOLUTE MODE
PURPOSE
To “rezero” the active Q-RPT in absolute measurement mode
See Section 3.5.1, Principle for a full explanation of the AutoZ function.
OPERATION
For the AutoZ function key to run AutoZ, AutoZ must be turned ON for the
active Q-RPT and measurement mode. AutoZ ON is indicated by <z> to the
left of the range designator on the first line of the main run screen. AutoZ
ON and OFF is set using [SPECIAL], <1AutoZ> (see Section 3.5.1). If AutoZ
is OFF for the active range, and measurement mode, <AutoZ OFF> is
displayed when [AutoZ] is pressed.
Running AutoZ in or parallel mode (see Section 3.5.7.3) autozeros both the
Hi and Lo Q-RPTs simultaneously.
To run AutoZ in absolute measurement mode, set absolute measurement mode
(see Section 3.3.3) and press [AutoZ] from the main run screen. The display is:
1. Active Q-RPT designator.
2. Current measurement mode (absolute).
3. Selection of source of P
std,0
reference to which
to AutoZ.
AutoZ Hi abs by:
1Entry 2COM2 3Lo RPT
Selecting <1Entry> allows the value of P
std,0
to be entered from the front panel keypad.
Selecting <2COM2> allows the value of P
std,0
to be read automatically from another
DHI RPMx connected to RPM4’s COM2 communications port.
Selecting <3Lo RPT> is shown only if the active Q-RPT is Hi and there is a Lo
Axxx Q-RPT in the RPM4. This selection allows the value of P
std,0
for the Hi
Q-RPT to be read automatically from the RPM4s Lo Q-RPT.
Allow the RPM4 to stabilize at atmospheric pressure and ambient
temperature for 10 to 15 minutes before running AutoZ in absolute mode.
If running AutoZ results in a value of P
offset
that is greater than ± 0.005 % FS of
the span of the Q-RPT that is being AutoZeroed, the Q-RPT and/or the reference
used as the source of P
std,0
may be out of tolerance or the AutoZ process may
have been faulty. Before activating a new P
offset
greater than ± 0.005 % FS of
the active Q-RPT, check to be sure that both the Q-RPT and the reference
were in good working order, properly vented to stable atmospheric pressure,
at the same height, and reading in the same pressure units when AutoZ was run.