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Note that when a four-wire function is selected (Ω4 or 4W-RTD
for the Model 2010), closing a channel (1 through 5) will also
close the paired channel. For example, if you close channel 2,
channel 7 will also close.
CAUTION
With a 4-wire function selected, do not
connect anything to channel 6. In the 4-
pole mode, channel 1 (which is the ref-
erence
junction)
channel 6. Therefore, when channel 1 is
closed, channel 6 also closes. Applying a
signal to channel 6 could damage the
reference junction.
The ROUTe:MULTiple:CLOSe/OPEN commands can also be
used to control scanner card channels. As the name implies,
you can specify multiple channels to be closed at the same
time. Note that channel 11 is the 2-pole/4-pole relay (see Fig-
ure 2-1). Closing channel 11 selects the 2-pole operating
mode. With channel 11 open, the 4-pole mode is selected.
CAUTION
When closing multiple channels, make
sure that you do not inadvertently con-
nect the reference junction (channel 1)
to other channels. Applying a signal to a
channel that is connected to channel 1
could damage the reference junction.
3.12 Typical applications
The information in the following para-
graphs pertains to the Models 2000, 2001,
2002, and 2010.
3.12.1 Resistor testing
The Model 2001-TCSCAN can be used to test up to seven re-
sistors using 2-wire measurements, or up to four resistors us-
ing 4-wire measurements. Such tests use the Model 2001 Ω2
and Ω4 resistance functions.
is
paired
with
NOTE
2-wire resistance tests
Figure 3-3 shows a typical test setup for making 2-wire resis-
tance measurements. The Model 2001-TCSCAN card provides
the switching function, while the resistance measurements are
made by a DMM. Since only 2-pole switching is required for
this application, one Model 2001-TCSCAN card can be used to
switch up to seven resistors. Note, however, that the 240Ω on
resistance of channels 5 and 10 may affect the measurement ac-
curacy of 2-wire resistance measurements made using these
channels. Generally, channels 5 and 10 should not be used for
2-wire resistance measurements unless the card is modified.
(See paragraph 4.8 in Section 4.)
Measurement accuracy can be optimized by minimizing re-
sidual resistance: make connecting wires as short as possi-
ble, and limit the number of connectors to minimize path
resistance. Another technique is to short one of the scanner
channel inputs, close the shorted channel, and then enable
the multimeter REL feature to null out path resistance. Leave
REL enabled for the entire test.
DMM
Input HI
Input LO
A. Test Configuration
Ω
DMM
B. Simplified Equivalent Circuit
Figure 3-3
2-wire resistance test connections
Operation
2001-TCSCAN
Out A
2
3-4, 6-8
9
DUTs
(7)
R
2001-TCSCAN
DUT
2
9
3-25
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Troubleshooting
