DH Instruments E-DWT-H, Руководство по эксплуатации и обслуживанию

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3. OPERATION
Page 57 © 2009 DH Instruments, a Fluke Company
 OPERATION
Press [SPECIAL] from the MAIN RUN screen to access the
SPECIAL menu. The display is:
1AutoZ 2remote 3head
4SDS 5prefs 6Punit
7intern 8cal 9reset
Note
Some screens, such as the SPECIAL menu, go beyond the two lines provided by
the display. This is indicated by a flashing arrow in the second line of the display.
Press the cursor control keys to move the cursor to access the lines that are not
visible or directly enter the number of the hidden menu choice if you know it.
SPECIAL menu choices include:
<1AutoZ> Manage the AutoZero function for the active Q-RPT (see Section 3.9.1).
<2remote> View and edit COM port (RS-232) and IEEE-488 interface settings. Select remote syntax
style (see Section 3.9.2).
<3head> Set HEAD function fluid and height unit of measure (see Section 3.9.3).
<4SDS> Feature not used in this RPM4-E-DWT model.
<5prefs> View and set screen saver time, keypad sound frequency, unit ID number, time/date,
security protection level (see Section 3.9.5).
<6Punit> Customize the [UNIT] key pressure unit of measure selections (See section 3.9.6).
<7intern> View internal barometer, view and set pressure reading rate setting, view incident log
(see Section 3.9.7).
<8cal> View and adjust RPM4-E-DWT Q-RPT and barometer calibration coefficients (see
Sections 3.9.8, 5.2.2).
<9reset> Access RPM4-E-DWT’s various reset functions (see Section 3.9.9).
3.9.1 <1AUTOZ>

PURPOSE
To turn ON and OFF the AutoZ function that allows the Q-RPT reading to be zeroed and the
dynamic compensation for atmospheric pressure changes feature. Also, view and adjust the
value of the AutoZ offset.
Note
To RUN the AutoZ routine that zeroes the Q-RPT, use [AutoZ] (see Section
3.7.10).
 PRINCIPLE
AutoZ Purpose and Principle
The RPM4-E-DWT AutoZero function (AutoZ) is used to achieve gauge measurement mode
with the RPM4-E-DWT’s intrinsically absolute Q-RPTs and to eliminate the influence of zero
drift on measurement uncertainty. AutoZ can also tare out fluid heads between the E-DWT-H
and the device under test.
The AutoZ functions provides full on-board support for regular zeroing including
determination, application and storage of offset values as well as dynamic compensation for
changes in atmospheric pressure between zeroing opportunities. The operator initiates
Q-RPT zeroing by pressing the
[AutoZ] key from the main run screen when zero
(atmospheric pressure) is applied to the RPM4-E-DWT Q-RPT.
The AutoZero function uses four values:
1. P
std,0
: Zero (atmospheric pressure) which is supplied by definition when the Q-RPT is
active, the reservoir shut off valve is close, the TEST shut off valve is open and the TEST
port is disconnected and filled with oil to the weep hole (reference level).