Keysight 34921A-34925A User’s Guide 17
34921A 40-Channel Armature Multiplexer with Low Thermal Offset
The 34921A 40-Channel Armature Multiplexer (40-Ch Arm MUX) is divided into
two banks with 20 latching armature switches (channels 1-20 and 21-40) in each.
This module also offers four additional fused relays (channels 41-44) for making
AC and DC current measurements with the internal DMM with no external shunts
needed. These current channels feature “make-before-break” connections to
ensure continuous current flow when switching from one current channel to
another. The current fuses are replaceable. Refer to the 34980A Service Guide for
specific information about these fuses.
This module also contains nine armature Analog Bus relays (channels 911-914,
921-924, and 931), four on each bank that can connect the bank relays to the
system Analog Buses and one that connects the current relays to the current input
of the DMM. Through ABus1 and ABus2 you can connect any of the channels to
the internal DMM for voltage or resistance measurements. Refer to the simplified
schematic on page 19.
Using program commands or the mainframe front panel, you can control each of
the channel switches individually, and thus configure the 34921A module in these
modes:
– two independent 20-channel 2-wire MUXes. This configuration requires
neither using external wiring nor connecting through the internal Analog
Buses.
– one 20-channel 4-wire MUX. This configuration requires neither using external
wiring nor connecting through the internal Analog Buses. For 4-wire resistance
measurements, the instrument automatically pairs channel n on Bank 1
(source) with channel n+20 on Bank 2 (sense) to provide these connections.
Four-wire controls occur only when doing 4-wire measurement operations
through the internal DMM, such as MEASure:FRESistance? or scanning a
channel previously configured as 4-wire.
ABus1 consists of three wires that are used for current and voltage
measurements. A separate current bus on ABus1 connects to the internal DMM
current measurement input and this bus can be connected only to channels 41
through 44. The current channel low (L) signal path is common with the ABus1
low (L) signal path. You cannot measure current and voltage on ABus1
simultaneously.
To Next Page
Loading...
Need help?
General
