M O L B L O C / M O L B O X L O W M A S S F L O W C A L I B R A T I O N S Y S T E M A F M E T C A L
C O N F I G U R A T I O N S
I N S T A L L A T I O N A N D O P E R A T I O N M A N U A L S U P P L E M E N T
©2000-2008
DH Instruments, a Fluke Company
Page 20
Entry of DUT pressure and temperature measurements
The AFMETCAL configuration system includes an RPM3-A0100b reference pressure monitor for accurate measurement of the gas
pressure at the DUT. No temperature measurement device is included in the AFMETCAL configuration system. COMPASS
software uses the DUT pressure and temperature measurements to make flow corrections for the effect of density changes on the
DUT. Pressure and temperature measurements can be manually entered into COMPASS and some devices, like RPM3, can be read
automatically by the computer running COMPASS. See Section 2.3.5.3 for instructions on connecting pressure and temperature
measurement devices to the flow path.
In the case of RPM3, a default hardware profile is already set up in COMPASS to collect its readings automatically. All of the
necessary commands to read the RPM3 pressure measurement are pre-set so that successful communication should be easy. An
RS232 cable is supplied with the AFMETCAL configuration system to connect the RPM3 COM1 port to your PC. If you do not
have an extra COM port available on your PC, molbox1’s COM2 port can be used to relay the RPM3 pressure reading to the PC.
Use the following steps to complete the communication setup with RPM3:
In the COMPASS
[Setup]
menu, select
[System]
. Set the
<Pressure Measurement>
selection to
<RPM3 / Ex.>
, and
click
[OK]
. If the
<Pressure Measurement>
selection is left as
<Manual>
, then the user will be prompted to enter visually
collected pressure data during tests.
In the COMPASS
[Setup]
menu, select
[Hardware]
and go to the
[Pressure]
tab. Double-click
<RPM3 / Ex.>
in the list
to display the
[Edit Pressure Measuring Device]
window.
Select the correct RS232 port. If you are using the molbox1 COM2, select
<Ref COM2>
as the RS232 port. Otherwise
select the COM port on your PC that is being used to read the RPM3.
The default command set in the RPM3 hardware configuration does not change the current measurement range used by the
RPM3. Whatever range is manually selected before a test will be used to supply pressure readings for the test. If you would
like your RPM3 hardware configuration to set the RPM3 to the same pressure range each time it is used by COMPASS, add
the following command to the Initialization Commands:
CONFIGURE1 HI
. This command will put the RPM3 into its
highest range, 100 psia. Substitute LO or MED for HI in the command to select one of the other ranges.
Make sure click
[SAVE]
before exiting the RPM3 hardware configuration.
If you have a temperature measuring device capable of remote communication, you must set up a hardware configuration for it using the
remote commands for that device and select the device by selecting
[System]
under the
[Setup]
menu and changing the
<Temperature
Measurement>
field. If the field is left as
<Manual>
, the user will be prompted to enter visually collected temperature data into
COMPASS during tests.
See the COMPASS for molbox User’s Manual Version 4.00 for more complete information on remote interfacing and temperature and
pressure data collection.
