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List of 34980A Measurement
Capabilities
• Temperature measured with
Thermocouples, RTDs and
Thermistors
• DC and AC volts
• 2- and 4-wire Resistance
• Frequency and Period
• DC and AC current
• 4 alarms for High/Low or both
limits for each channel
• Digital I/O
• Analog outputs (DAC)
The 34980A mainframe also
includes four 2-wire internal
analog buses. This is a
differentiating 34980A feature and
not included with the 3499A/B/C.
The analog buses can be used to
route measurements directly to
the internal DMM or connect the
mainframe modules to external
instruments. The analog bus can
be used to extend modules such as
the matrix switch modules, or
provide additional signal routing
between modules.
Mainframes
The 34980A Multifunction
Switch/Measure Unit consists of
an eight-slot mainframe with an
optional DMM. The DMM is
mounted directly behind the front
panel so it does not require any of
the available eight module slots.
A choice from 19 different
modules can be plugged directly
into the eight-slot mainframe.
In comparison, the 3499 Family
has mainframes in three different
sizes: A, B, and C that house five,
two, and nine modules
respectively. The 3499 Family
offers a selection of 30 plug-in
modules, 13 of which are the
earlier generation HP 3488A
Switch/Control Unit modules.
Since some of the modules were
designed for the 3488, and some
modules specifically for the 3499,
there is duplicate functionality
between the modules.
As test systems and capability
needs expand there is a call for a
greater number of switch
channels within one system. The
34980A switch modules are
designed for high switching
channel count. The 34980A eight-
slot mainframe fully loaded with
2-wire multiplexer modules
houses a total switch channel
count of 560. The 3499C nine-slot
mainframe fully loaded with 2-
wire multiplexer modules houses
a total of 360 switch channels.
For a quick summary of the
maximum switch channel count
for the switch systems
mainframes, see Table 1.
Mainframe Mainframe Size Number of Module Slots Maximum Number
of Channels (2-wire)
34980A Full Rack, 3U 8 560
3499B Rack, 2U 2 80
3499A Half Rack, 2U 5 200
3499C Full Rack, 5U 9 (electrical)/ 360
14 (physical)
Table 1. Max 2-wire Mux channel count per Mainframe