DH Instruments COMPASS FOR MOLBOX, User Manual

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COMPASS

for molbox™ User’s Manual
© 1998-2003 DH Instruments, Inc .
Page 92
Table 29. Test Definition Editor, [Control] Tab Fields
FEATURE DESCRIPTION
Flow Control
(drop down list)
Determines how flow will be controlled to set flow during tests. The choices are:
•
Manual: Flow will be set manually by the operator, not by a device that
COMPASS can control remotely. As a test is run, the operator will be
prompted to set the flow to the target value at each point. Use this choice
when a manual flow control system or an automated controller with which
COMPASS cannot communicate remotely is being used.
•
DUT: Flow will be set by the DUT. The DUT is a flow controller and has
been set up as a controller in the DUT Definition [Range] and [Set] tabs
(see Sections 8.5.4, 8.5.9). If the DUT being tested is not specified as a
<Controller> , an error will occur during test initialization.
•
Other Controller: Flow will be set automatically by COMPASS using a flow
controller which COMPASS can control remotely but which is NOT the DUT.
The flow controller to use is specified by selecting it from the <Controller>
drop down list on the [Control] tab. COMPASS automatically performs the
necessary unit conversions when the flow controller is used.
Controller
(conditional drop
down list)
Specifies the flow controller to use when <Other Controller> has been selected
as the <Flow Control> method. The drop down list is made up of flow
controllers set up in the Hardware Definition [Flow Controller] tab (see Section
10.3.6). These must be supported by a <Set point power supply> in the
System Configuration (see Section 10.2).
Jog flow before
dwell
(check box)
If this is checked, test execution will pause just before the dwell phase of the test
point to allow the flow rate to be adjusted before the reference and DUT
readings are taken. If flow control is automated, adjustments are made using
the
<Flow Control> panel (see Section 6.6.8). This feature is most often used to
adjust the flow to the DUT’s cardinal point when testing a visual output flow
meter.
<Jog flow before dwell> has no affect when flow control is manual and
is mutually exclusive with the <Flow Regulation> option.
Regulate Flow
To
(drop down list
and entry field)
This feature is used to specify to what device’s reading the flow should be adjusted
when an automated flow control device is included in the test. The choices are:
•
None: COMPASS calculates and sends the command for the target flow
point to the controller and makes no further adjustments. In this case, how
close the final flow at a flow point will be to the desired value depends on
the calibration of the controlling flowmeter. Check
<Jog before dwell> if
you want to adjust flow at the point, for example to put the DUT reading on a
cardinal point.
•
Molbox flow: At each flow point in the test, COMPASS continuously
readjusts the set point command to the flow controller to adjust the flow to
the target value
as indicated by the molbox . This option causes the final
flow value at a test point to be very close to the cardinal point as read by the
molbox.
•
DUT flow: At each flow point in the test, COMPASS continuously readjusts
the set point command to the flow controller to adjust the flow to the target
value
as indicated by the DUT. This option causes the final flow value at a
test point to be very close to the cardinal point as read by the DUT. For this
selection to operate, the DUT cannot be a manual entry output type.
The Regulation Delay entry determines the time, in seconds, between regulation
loop cycles. This is how often the set point will be readjusted to get closer to the
target value. Setting this value to a time value that is too short relative to the
response time of the flow system will result in unstable flow control.