Keysight Technologies 34921A User Manual page 18

– one 40-channel 2-wire MUX. You must use external wiring or connect through
Low thermal offset voltage makes the 34921A ideal for low-level signal switching.
The 34921T optional terminal block provides a built-in thermocouple reference
junction that helps minimize errors due to thermal offset when you measure
thermocouples.
This module has capability to scan as many as 100 channels/second using the
internal DMM. With the automatic "break-before-make" connection operation,
you are assured that no two signals are connected to each other during a scan.
When using the module in a non-scanning mode, you can close as many channels
as you wish.
This module is safety interlock protected, which means whenever the D-sub
connector end of the modules is exposed, the Analog Bus relays automatically
open and disconnect from the Analog Bus. For more information, see
Interlock"
When power is off, all channel relays maintain state, and the Analog Bus relays
open.
18
the internal Analog Bus relays for this configuration. For example, closing
Analog Bus channels 913 and 923 connects Bank 1 and Bank 2 through
ABus3. Or, externally you can connect COM1 to COM2 to create this
configuration.
on page 11 and "34921A D-Sub Connectors"
Keysight 34921A-34925A User's Guide
"Safety
on page 20.