One-Wire Mode; Interlock Protection; Overvoltage Protection - Agilent Technologies 34921A User Manual

One-Wire Mode

• two independent 40- channel 1- wire MUXes. This configuration requires
• one 80- channel 1- wire MUX. You must use external wiring or connect

Interlock Protection

This module is interlock protected, which means whenever the D- sub
connector end of the modules is exposed, the Analog Bus relays
immediately open and disconnect from the Analog Buses. For more
information, see

Overvoltage Protection

This module also features high voltage detection (< 100 V) and current
limiting circuitry to protect the FET relays. This circuitry senses current
flows from input overvoltages. These overvoltages may come from either
the MUX input or from the Analog Buses. In addition, each channel is also
protected from input overvoltages with a resistor.
When overvoltage is detected, all relays (Analog Bus and FET) are opened.
While in the overvoltage state, any attempts to close any Analog Bus or
FET switch, results in an error status response from the module.
Once in the overvoltage state, you must restore normal module operation
with one of these actions:
• using the SYSTem:CPON <slot> command. This affects only the
• using the *RST command. This command resets the mainframe and all
• cycling system power. This affects all installed modules.
If the overvoltage situation is not resolved, clearing the overvoltage will
result in a new overvoltage event occurring immediately.
Further FET protection is assured only as one channel in each bank is
closed at any time. Thus this module will operate as only a 1:N MUX
module. For more information about FET channel closures, refer to
Agilent 34921A-34925A Low Frequency Multiplexer Modules User's Guide
neither using external wiring nor connecting through the Analog Bus
relays.
through the Analog Bus relays for this configuration.
Because all bank relays supply only HI signals, you can apply a
N O T E
LOW signal through COM1 L or COM2 L when you are making
2-wire resistance measurements in 1-wire mode.
"Safety Interlock"
module specified.
installed modules to the Factory configuration. This affects all installed
modules.
34925A 40/80-Channel Optically-Isolated FET Multiplexer
on page 3.
page 4.
35