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7-2
Scanning fundamentals
7702 module scanning
The Model 2790 can scan the channels of up to two installed Keithley Model 7702 switching
modules. Each scan channel can have its own unique setup. Aspects of operation that can be
uniquely set for each channel include function, range, rate, AC bandwidth, rel, filter, digits,
math, Ω offset compensation, TEMP transducers, limits, channel average, channel ratio, and
volts dB.
klqb
There are SCPI commands to query the capabilities of the installed switching modules. For
example, the following queries are provided to determine which channels of a Model 7702 in
slot 1 are available for volts/2-wire ohms and which channels are available for amps. Note
that the returned values for the Model 7702 switching module are shown in parenthesis.
SYSTem:CARD1:VCHannel[:STARt]?
SYSTem:CARD1:VCHannel:END?
SYSTem:CARD1:ACHannel[:STARt]?
SYSTem:CARD1:ACHannel:END?
All the commands to query switching module capabilities are covered in
Channel assignments
A switching module has a certain number of channels. For example, the Model 7702
switching module has 42 channels (1 through 42). When you encounter a 1 or 2-digit
channel number in this manual, the switching module channel is the point of discussion.
A switching module can be installed in one of two slots of the mainframe. Therefore, to
close/open or scan a channel, it is necessary to specify the slot location and channel num-
Model 2790 SourceMeter
Readings for scanned channels are automatically stored in the buffer. With
buffer auto clear enabled (which is the default), the buffer clears when the scan
is started. When disabled, scan readings are appended to the buffer. The
TRACe:CLEar:AUTO <b> command is used to enable/disable buffer auto clear
(Section
6).
A pseudocard can be installed in an empty slot. With the 7702 pseudocard
installed, the instrument will operate as if a Model 7702 switching module is
installed in the slot. This allows the user to configure a scan and exercise its
operation before the switching module is installed in the Model 2790. Use the
following commands to install 7702 pseudocards in empty slots:
SYSTem:PCARd1 C7702
SYSTem:PCARd2 C7702
Pseudocards for other switching modules can instead be installed. Details on
installing other pseudocards are provided in
®
Switch System Reference Manual
'Install' 7702 pseudocard in slot 1.
'Install' 7702 pseudocard in slot 2.
Section
2.
' Query first volt/Ω2 channel(7702; "1").
' Query last volt/Ω2 channel (7702; "20").
' Query first amps channel (7702; "21").
' Query last amps channel (7702; "22").
Table
15-8.
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