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The programs in the Data Acquisition Pac perform many tests to verify that the setup information and
data file operations for the =TREIF, MIIWMITUOR, and L.IJ5 programs are proper.
Under normal
conditions, it should be impossible to configure a setup that cannot be executed correctly with the
HP 3421 A Data Acquisition/Control Unit, as long as the WEF IF" routines accept the setup information.
There are several instances where normal operation of these programs could encounter errors:
eo Low Memory: Large setups may require a great deal of memory. Such setups, combined with calls
to custom, conversion, or limit subprograms, can in some cases overflow availa': memory.
e Corrupt Setup: A setup which has not been validated by the "EF IF" routine could still request
an impossible function from the HP 3421A, such as DICWOL TZ 024 3 when slot 2 contains a
digital card.
e Broken Loop: During execution, a power "glitch" or operator error might cause a device to reset or
lockup, the loop to break physically, or an invalid frame to return to the HP-71.
The STEIFF, MOMITOR, and LOG programs utilize error traps in an attempt to protect against the
majority of problems that occur. When data is being collected, an error such as L.ODOF ERECKEM causes
a call to a subprogram RECOVER.
The HP-71 scans user memory before looking in plug-in ROM modules when scanning for the
FECOMER subprogram.
This gives a "hook" to create a custom error handling routine.
If no
subprograms called FELCCOYEFEare found in user memory, the file LITILITY in the Data Acquisition
Pac module contains a subprogram called FEECIYEE, which will be executed.
G.1 LOW MEMORY CONDITIONS
A low memory error can occur under a variety of conditions, such as when very large setups are being
executed, when large data files are being created in memory, or when user subprograms are being called.
If a low memory condition occurs within the calling program, a message is displayed, and depending upon
the module being executed, a branch to a menu usually occurs. The LI program will end if a low
memory condition occurs during execution.
L.IJ(5 will preserve the data that has been collected and
display a message. The STFIF and MIMI TOR programs will return to the main menus with the EF:
prefix if a low memory condition occurs while data is being collected.
The calling programs cannot protect against low memory conditions in user-written subprograms other
than to ensure that sufficient memory exists to set up the call.
If there is doubt about the memory
available, the subprograms should employ some form of test to ensure that sufficient memory exists to
execute properly.
For example, if a custom program is written for L.[Il3 which requires an array of 100
real numbers, a test should be made to ensure that there is room for the array.
To minimize memory usage, save unneeded files to mass storage and load the setup information from a
mass storage file, rather than keeping a copy in memory.
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