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will introduce a massive amount
of documentation changes (not to
mention any possible signal integrity
issues with changing cable lengths
to the mass interconnect). This
form-factor challenge is one of the
many reasons that modular platforms
like PXI (and formerly VXI) have
dominated the Aerospace/Defense
ATE market for the last 30 years. By
following the strict guidelines of the
PXI specification, a scope from vendor
A will be the same size and utilize
the same backplane power as vendor
B, giving test engineers an easier
upgrade path for their systems.
The second hurdle in the road is
hardware abstraction layer (HAL)
integration. Any test system that is
expected to last for five to 10+years will
inevitably have planned maintenance
and operational costs. These are
significantly reduced by abstracting
vendor-specific hardware and drivers
into a HAL or measurement abstraction
layer (MAL). The test engineer is also
tasked with evaluating the driver stack
of the new instruments to ensure
they plug into the HAL to mitigate the
risk when migrating the thousands of
TPSs still to come. Many HALs utilize
the IVI driver class where possible
and supplement with Plug-and-Play
drivers. Since this example is an
oscilloscope, we’ll make a blanket
claim that the test engineer has it
“easy” and gets a pass on software
because there is an existing IVI class
specified for oscilloscopes.
Hardware Abstraction Layers (HALs)
significantly mitigate the impact of
hardware obsolescence, but are
difficult to justify in the absence of a
long-term support strategy.
Hardware Abstraction Layers (HALs) significantly mitigate the impact of hardware obsolescence, but are
difficult to justify in the absence of a long-term support strategy.
While difficult
to accomplish,
emulating legacy
instrument
capabilities
greatly reduces
the risk of TPS
migration issues.
Software-
Designed,
or Synthetic
Instruments,
offer a unique
approach to
test equipment
emulation
A third and often hidden hurdle is the
answer to the question: is better really
better?The specifications of this new
oscilloscope are multiple generations
of technology ahead of the obsolete
equipment, so where’s the issue?
The issue comes when, for example,
you insert this new oscilloscope
into the system and the rise time or
settling time measurements change
significantly because you’re sampling
at three, five, or 10times the rate of
the previous instrument, which results
in dozens of incompatible TPSs that
previously provided great system
utilization. Another issue arises
when legacy TPSs require trigger
functionality that instrument vendors
made obsolete years or decades prior.
In this situation, the test engineer is
challenged with looking across the
entire database to identify which
TPSs will be broken by inserting a
new instrument that does not support
the legacy trigger functionality - a
database which often doesn’t exist
and requires weeks or months of
manual effort to identify.
In order to minimize the unknown
risks of TPS rehosting, many test
engineers are taking advantage of
software-designed instruments (SDIs)
to give more flexibility in the rehosting
process. Software-designed (also
known as synthetic) instruments
combine core analog and digital
front-end technology with powerful,
user-programmable FGPAs to provide
the most flexible instruments on the
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