Loopback Test: For Data Validation
A loopback test
may
be performed if you are required to validate the precision of the
G.C. or Data System's analog to digital conversion. This test requires the user to install a
jumperwire on theND board inside the G.C. or Data System.
Description of Test:
A jumper wire is installed on theND board between 'temperature program one',
(TP1), and 'channel one signal input', (Sig. 1+). A data file is then loaded into channel
four.When the 'Ioopback' mode is selected in PeakSimpIe, the data on channel four is
routed out TP1 to the channei one signal input. When a chromatogram run is started,
channel onewill begin to reproduce the data loaded into channel four. After the run has
completed, area counts from a specific data peak
may
be collected and the run repeated
several times. After at least three runs, the user
may
then calculate the average area
counts and the percent relative standard deviation,(%RSD) and thus the precision of the
ND converter. Less than 0.5%RSD is typical for the SRI Model 202 and 203ND boards.
Setting Up The Hardware:
With the G.C. unplugged, remove the six screws securing the bottom cover. Flip the
G.C. on its backand locate theND board on the right-hand side. Remove
any
wires from
'TP1' and 'SIG 1+' and add an insulated 22 AWGwire between TP1 and SIG 1.
Refer to the diagram below for jumper placement.
1········1
1············1
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C D ~ ~Q H
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'0_
04TAI'OIlT
~0It
ClIIH!CT'IONTO
u_. , _
C-.nvl
-
SINGLECHANNEL
LAWSON203BOARD
FOURCHANNEL
LAWSON 202 BOARD
'0_
041._r
"011
C_CnoNTO
,-----,'~~
ADDAJUMPUfROfII TPl TO$IGI.
ANOVeRIFY$IG l_1SGROUNDED
c.-..
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('I
VOLTO
"""'4
•
!
•
•
Most systems will
contain theFour
Channel 202 Board.
Also, verify that SIG 1–
is grounded. Add
another jumper if
needed.
Some systems will
contain the Single
Channel 203 Board.
Also, verify that SIG 1–
is grounded. Add
another jumper if
needed.
You could also run the
TP1 wire to SIG 1+
through a relay for
automatic hardware
setup.
