Agilent Technologies L4400 - Manual (Page 112)

100 L4400 User’s Guide
4 L4421A 40-Channel Armature Multiplexer
Low Frequency Multiplexer Switch Instrument
The L4421A low frequency multiplexer (MUX) switch module features
two banks of channels that provide broad multiplexing and measuring
capabilities. You can close more than one channel in each bank
simultaneously (N:1 configuration) on the multiplexer.
Safety Interlock The Analog Buses of the L4400 series
instruments are capable of carrying 300V signals. The L4421A
instrument has a hardware Safety Interlock feature that
automatically opens the analog bus relays when the associated
interlock pins on the D-sub connectors (faceplate) lose continuity.
This prevents signals on the analog buses from being present on
the D-sub connector pins. Optional terminal blocks available
from Agilent automatically provide continuity for these interlock
pins. If cables are used, you must provide continuity for the
interlock pins in your DUT assembly. See the pinout information
later in this chapter for the location of interlock pins on each
module.
The L4421A has analog bus relays on each of its two banks.
Therefore, the interlock pins are present on both the Bank 1 and
Bank 2 D-sub connectors on the module.
Normally, if you attempt to connect to the analog buses without

a terminal block or cable connected, an error is generated.

The SYSTem:ABUS:INTerlock:SIMulate command
allows you to temporarily disable errors generated by the Safety
Interlock feature and enables the simulation mode. Although
Safety Interlock errors are suppressed in this mode, the actual
analog bus relays affected by the Safety Interlock are disabled as
long as no terminal block or cable is connected to the module.
L4421A Measurement Functions
The L4421A supports the measurement functions shown in Table 4- 1.
Measurements are made by routing the signals on the multiplexer to a
separate digital multimeter (DMM) instrument using the L4421A analog
bus.
N O T E