System Channel Operation - Keithley 2750 User Manual

2-6 Close/Open Switching Module Channels

System channel operation

The system channel is a closed measurement channel that is internally connected to the
internal DMM Input of the Model 2750. The system channel number is displayed on the
Model 2750. For a 4-wire function (i.e., Ω4), the paired channel for the system channel is
internally connected to DMM Sense. The paired channel is not displayed on the Model
2750. When triggered, the DMM performs a measurement and displays it on the Model
2750.
The system channel is selected by closing a measurement channel using the system chan-
nel close keys. These include the
option). See
Other important points about system channel operation include the following:
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•
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NOTE
"Controlling the system channel," page
There can only be one system channel. This is the channel that is presently dis-
played (and closed) on the Model 2750. When a channel is not displayed, there is
no system channel.
When a measurement channel is closed, the input backplane isolation channel also
closes to connect the system channel to DMM input. For a 4-wire function, the
paired channel and the sense backplane isolation channel also close to make the
sense connections to the DMM.
When a different measurement channel is closed, the previous system channel
opens. The newly closed (and displayed) measurement channel becomes the sys-
tem channel.
The system channel close keys can only close measurement channels that will
automatically connect to the DMM. Non-measurement channels cannot be closed
by the system channel close keys.
Use the VIEW option of the CARD menu to display all closed channels in the
mainframe (see "CARD menu," page
Model 2750 Multimeter/Switch System User's Manual
and keys, or the CLOSE key (SINGLE menu
2-9, for details.
2-28).