DH Instruments PPCH, Руководство по эксплуатации и обслуживанию

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3. OPERATION
Page 81 © 2009 DH Instruments, a Fluke Company
3.5.2.4 <5RS232 SELF-TEST>
The RS232 self-test is provided to check the PPCH COM ports and the interface
cable independently of an external device or computer.
If you are having difficulty communicating with PPCH from a host computer
using RS232,
the RS232 self test can help establish that the PPCH COM1 port
you are trying to communicate with and the interface cable you are using are good.
To run a self test of the RS232 ports (COM1 and COM2), press
[SPECIAL]
,
<2remote>
,
<5RS232test>
.
The display prompts you to connect COM1 to COM2 using a standard pin-to-pin
DB-9F to DB-9M RS232 cable (see Section 4.2.1.1).
Once the cable has been installed, press
[ENT]
to run the self-test. The test is first
executed in the COM1
→
COM2 direction and then in the COM2
→
COM1 direction.
If the COM1
→
COM2 test passes: <PASSED>
displays briefly and the test
proceeds to COM2
→
COM1.
If COM2
→
COM1 passes: <PASSED>
is displayed briefly followed
by the conclusion,
<The RS232 test
has PASSED>
.
If a test fails:
Execution is suspended until
[ENT]
is
pressed.
The PPCH RS232 test can fail for three reasons:
1. The RS232 cable being used is incorrect (see Section 4.2.1.1 for
information on the correct cable).
2. COM1 and COM2 do NOT have the same serial communications settings
and therefore cannot communicate together (see Section 3.5.2.1 to set
the COM ports).
3. COM1 or COM2 is defective.
The reason for failed communications is almost always a cable or incorrect RS232
interface settings. Be sure that these are correct before concluding that a COM
port is defective.
3.5.3 <3HEAD>
 PURPOSE
To view or change the properties of the HEAD function (see Section 3.3.7) including the unit
of measure of length for head height entry and the test fluid type and species for density
calculations.
 OPERATION
From the MAIN RUN screen, pressure
[SPECIAL]
,
<3Head>
.
Select the desired height unit of measure and press
[ENT]
.
Select
<1gas>
or
<2liqud>
depending on the pressurized medium between the PPCH and
the height at which pressure is to be calculated. Select the gas or liquid species. The liquid
selection
<3User>
, is to create a custom liquid with a user entered density.
Use
[HEAD]
to set a fluid head height if desired (see Section 3.3.7).