PG7000™ OPERATION AND MAINTENANCE MANUAL
© 1998-2008 DH Instruments, a Fluke Company
Page 122
After the string value has been entered
the display is:
Reply conv coef:
1.000000 Pa/unit
<conv coef>
is the conversion coefficient that PG7000 will use to convert
readings from the external barometer to the pressure unit of measure
Pascal
[Pa]
. If the readings from the external barometer are NOT Pascal, edit
the conversion coefficient value as needed to convert the readings to Pascal.
When the conversion coefficient is entered
the next setup screen is opened. The
display is:
Leading characters to
Strip: 0
This entry specifies the leading characters in the return string that precede the
numerical value of the pressure. PG7000 will strip the specified number of
characters from the front of the return string and assume that the next character
is the first number defining the current value of atmospheric pressure.
To verify whether external barometer communications have been set up properly,
select a SETUP file that specifies COM2 under AtmP (see Section 3.10) and verify
that communications with the external barometer are achieved. Then view current
barometer readings in the AMBIENT run screen (see Section 3.9.6) and verify that
the readings are correct. Note that a fluid head correction should be set if the
external barometer is not at the PG7000 reference level. This correction may cause
the reading of the external barometer and the value of ambient pressure indicated
by the PG7000 to not be identical (see Section 3.11.3.3).
For communications with an external barometer on COM2 to be established
properly, the inquiry string to send to the barometer must be defined following this
section and the PG7000 COM2 port and barometer COM port must have the same
communications settings. Press [SPECIAL] and select <5remote>, <2COM2>,
<1settings> to set up PG7000 COM2 communications settings. When unable to
establish communications between COM2 and the external barometer, consider using
the PG7000 RS232 self test to verify COM2 operation (see Section 3.11.5.3). If
both a barometer and a vacuum gauge are connected, the barometer must always be
the first device connected to the PG7000 Platform COM2.
3.11.5.5
EXTERNAL VACUUM GAUGE COMMUNICATIONS
(COM2) (PG7601 ONLY)
PURPOSE
To set up communications with an external vacuum gauge from which PG7601
will read the value of reference vacuum under the bell jar used in the calculation of
absolute pressure in absolute by vacuum measurement mode (see Section 3.9.4).
The source of the value of vacuum pressure used by PG7000 in its internal
calculations is determined by the Vac setting in the current SETUP file (see Section
3.10). Setting up communications with an external vacuum gauge does NOT set
PG7601 to utilize the external vacuum gauge.
PRINCIPLE
PG7601 uses a value of reference vacuum under the bell jar in its calculation of
the pressure defined by the PG in absolute by vacuum measurement mode (see
Section 7.2). The source of the value is determined by the Vac setting in the
current SETUP file (see Section 3.10). One of the possible sources is
COM2
,
