Keithley 7701, User Manual, Page: 9 / 33

4 Model 7701
Dual independent multiplexers
WARNING Multiple channel operation should only be performed by experienced test engineers who
recognize the dangers associated with multiple channel closures.
Multiple channel operation (
ROUT:MULT:CLOS
command) allows individual control of switching module
channels. Multiple channel operation allows the switching module to be configured as two independent mul-
tiplexers. The Model 7701 is normally used as a single 1
×
32 multiplexer, but it can also be configured as
two 1
×
16 multiplexers.
In Figure 1 , the open position of channel 33 is shown. When channel 33 is closed, Multiplexer 1 (channels 1
through 16) are isolated from Multiplexer 2 (channels 16 through 32).
For the dual multiplexer configuration, only Multiplexer 1 channels can be internally connected to the DMM
of the Model 2700/2750. Closing channel 35 allows channels 1 through 16 to be measured by the DMM.
When using the dual multiplexer configuration, Multiplexer 2 must be isolated from the sense terminals of
the DMM. This can be done by keeping channel 34 open, or by not installing the screw terminal jumpers to
DMM Sense.
Connections and wiring
WARNING The following information is intended for qualified service personnel. Do not make
switching module connections unless qualified to do so.
To prevent electric shock that could result in serious injury or death, adhere to the fol-
lowing safety precautions:
• Before removing or installing the switching module in the mainframe, make sure
the mainframe is turned off and disconnected from line power.
• Before making or breaking connections, make sure power is removed from all exter-
nal circuitry.
• Do not connect signals that may exceed the maximum specifications of the Model
7701. Specifications are provided at the end of this section.
WARNING The Model 7701 is configurable to be connected to the internal DMM via the supplied
jumpers and the screw terminals. When connected to the internal DMM, all other mod-
ules must be derated to 150VDC or 150Vrms (212V peak) for AC waveforms.
Screw terminals
The screw terminals of the Model 7701 are shown in Figure 2 . As shown, screw terminals are provided to
connect the switching module channels to the DMM. User-configurable screw terminals are also provided to
allow external input to bypass the switching module channels.
Four jumpers are supplied with the Model 7701 for use with the screw terminals. As shown in Figure 2 , the
Model 7701 is shipped with the jumpers not installed. With the jumpers not installed, all input to the Model
7701 is electrically isolated from the DMM.