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Introduction
In addition to the measurement/control option assemblies, the HP 3421A can accommodate an option 214
12-Volt power assembly (which allows long-term remote operation using an external battery) or an
HP-IB option board (which allows the HP 3421A to operate from an HP-IB controller).
Some applications may require the system to go to a known-safe state in
case of an equipment or power failure. For example, if a furnace heater is
being controlled, it should go to the off state in case of failure.
Note the
following:
The HP 3421A Data Acquisition/Control Unit and the Option 020, 021,
and 022 Multiplexer Assemblies use latching relays. The state of these
relays can only be altered under program control. Under most conditions
of failure, the relays will remain in whatever state the program last set
them,
The HP 3421A Option 050 Digital I/O Assembly output switches are not
latched.
Under most conditions of failure the switches will go to the open
state.
It is up to the programmer to provide the appropriate circuitry and
recovery programs to ensure that the system under control goes to a
known-safe state in case of an equipment or power failure. In some
applications serious damage or injury may otherwise occur.
1.4 APPLICATIONS
The HP-71 Data Acquisition Pac simplifies HP 3421A control by extending BASIC with a series of
instrument -control statements and keywords, and by providing application programs that use the new
keywords.
The statements and keywords are used to initialize the instrument (for example, IMI T=4:1), close a
channel on a multiplexer card (for example, :L.00=k
1) or take measurements (for example,
CHEMO. T= Cd 2). Additional statements and keywords are provided for string manipulation, temperature,
and time/date conversions.
The application programs are built on the foundation of the new keywords and statements. The major
applications provided are the front panel program, a strip chart program, a system monitoring program, a
data logging package, and a data transmission program. The front panel program allows the user to
interactivly control the HP 3421A and take readings from various sensors. The strip chart program prints
a "real time" strip chart from various sensors. The system monitoring program provides a low cost solution
for monitoring the status of a system on a video interface.
The data logging package allows the user to
specify and execute a data capture sequence.
The data transmission programs can send data to the
HP 44456 software package for the HP Series 200 computer family, or to MS-DOS® computers such as
the HP 150.
MS-DOSis a registered trademark of Microsoft Corporation.
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