DH Instruments COMPASS FOR MOLBOX, User Manual

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COMPASS
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for molbox™ User’s Manual
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© 1998-2003 DH Instruments, Inc .
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5.1 OVERVIEW
This section contains several generic application examples that cover many common COMPASS setups.
Using these examples and the How Do I? tips in Section 4.1 will greatly simplify the learning process to
get a test started. Although each example may not include explicit instructions on all test steps, there are
three required steps that must always be followed before a test can be run:
Create (or select) a DUT Definition.
Create (or select) a Test Definition.
Set up the Hardware Configuration to support the DUT and Test Definitions.
Each of the examples in Sections 5.1.1 to 5.1.6 uses generic DUT command information. Refer to the
actual DUT documentation when trying to run a test following any of these examples.
5.1.1 EXAMPLE #1
“How do I use a molbox1 reference to automatically calibrate a DUT that has a range of
0 to 50 sccm and uses an RS485 or digital interface?”
Most manufacturers that use RS485 and digital interfaces also supply a converter box that
transforms the communications interface into RS-232. If this converter is available, set up
the DUT Definition with an RS-232 as its
<Output Type> on the DUT Definition [Read] tab.
Without this converter box, COMPASS cannot communicate with this type of DUT.
For this example, assume the Test Definition “Test1” was previously set up for DUT control
and a sequence of test points that fit the requirements of the DUT has been set up (see Section 9).
The DUT in this example outputs in the format “N+24.55” as 24.55 % (corresponding to 12.28 sccm)
when passed the command (02H)“01RFX.” The (02H) is a non printable ASCII control code
that has a hexidecimal value of 2 (see Section 8.5.8). These codes are sometimes required
by DUTs when using an RS-232 converter. The DUT set command is “(02H)”01STD###”
where” ###” represents the numerical target flow value as a percentage of full scale. The objective
of this example is to demonstrate the basic requirements of a direct flow output DUT using a
remote command and how to use
[Setup] , [System] to configure the system hardware.
The DUT in this example uses an RS-232 interface, however changing the DUT <Output Type>
on the DUT Definition [Read] tab to IEEE-488 is all that is required to use IEEE-488.