Multiplexer Switching Examples; Resistor Testing - Keithley 7021 Instruction Manual

Operation
Reading digital I/O input channels
The following SCPI commands are used to read the status of
digital I/O input channels:
:SENSe2:DATA? <list>
:SENSe3:DATA? <list>
:SENSe4:DATA? <list>
:SENSe5:DATA? <list>
:SENSe6:DATA? <list>
:SENSe7:DATA? <list>
:SENSe8:DATA? <list>
:SENSe9:DATA? <list>
:SENSe10:DATA? <list>
:SENSe11:DATA? <list>
The conventional form for the <list> parameter includes the
slot and input channel number. However, for these com-
mands you do not need to include the slot number. For exam-
ple, you can send either of the following two commands to
read input channel 2 in slot 6:
or :SENSe7:DATA? (@2)
:SENSe7:DATA? (@6!2)
After the mainframe is addressed to talk, the response mes-
sage will indicate the state of each listed input channel. A re-
turned "0" indicates that the channel is off (open), and a
returned "1" indicates that the channel is on (closed).
The following program fragment reads channel 3 of a digital
I/O card installed in slot 1:
PRINT #1, "output 07; sens2:data? (@3)"
PRINT #1, "enter 07"
LINE INPUT #2, A$
PRINT A$
5-6
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Read input channels; slot 1
Read input channels; slot 2
Read input channels; slot 3
Read input channels; slot 4
Read input channels; slot 5
Read input channels; slot 6
Read input channels; slot 7
Read input channels; slot 8
Read input channels; slot 9
Read input channels; slot 10
The first statement reads input channel 3 (slot 1). The second
statement addresses the mainframe to talk (sends response
message to computer). The third statement reads the re-
sponse message, and the last statement displays the message
(0 or 1) on the computer CRT.
The above program fragment is modified to read all 10 digi-
tal I/O input channels in slot 1 as follows. The modified state-
ment is shown in bold typeface.
PRINT #1, "output 07; sens2:data? (@1:10)"
PRINT #1, "enter 07"
LINE INPUT #2, A$
PRINT A$
The response message will include a "0" (off) or "1" (on) for
each of the 10 input channels (i.e., "0, 0, 0, 1, 0..... 0, 1").

Multiplexer switching examples

This paragraph presents some typical applications for the
Model 7021. These include resistor testing and transistor
testing. It also shows how to use the Model 7021 with a ma-
trix-digital I/O card (Model 7022).

Resistor testing

The Model 7021 can be used to test a large number of resis-
tors using only one test instrument or group of instruments.
Such tests include two-wire and four-wire resistance mea-
surements using a DMM and low-resistance measurements
using a current source and sensitive digital voltmeter, as dis-
cussed in the following paragraphs.