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Welcome to our
Home Page for August 2014
This month our
Product Cateory focus is:-
DAQ &
DSP & GPIB in all formats
Plug
in buses, IP, Serial, USB, Bluetooth, Wifi
A total of 25
companies with a huge range of DAQ, DSP, DSP+DAQ Combos &
GPIB product.
DAQ Techology
DAQ, or Data Acquisition has
been going on forever. All early systems were manual.The person
with the Clip Board back in history was a DAQ collector and still
is.
When Digital computers arrived
in the 50's, there was a concerted effort to automate DAQ by
building interfaces to computers that DAQ systems could be connected
to. Who was first is anyones guess but DEC seem to be first with
commercial buyable product.
I had a 1964 DEC computer with
an multi channel 12 bit ADC in it, that was a breeze to use,
even with Assembler or maybe because of Assembler.
The introduction of the IBM PC
in 1982 saw the start of a massive increase in Computer based
DAQ. Cost reduction was the main driving force.
ISA bus made it possible to build
excellent plug in DAQ boards and performance was very fast with
DOS, with even real time performance.
Windows messed everything up
because it was so unpredictable in its bus and interrupt response
latencies and all sorts of techniques where developed to make
DAQ plug in boards run in Windows well.
Real Time DAQ almost disappeared
forever on PCs when Windows came along. Only realtime computers
running Unix, DEC RT-11, HP RTE etc could do it, All very expensive
and very rapidly becoming orphans or dinosaurs.
If you wanted real time in your
PC you had to have a DAQ with a micro on board and they were
available.
Some companies have got around
this by using programmable FPGAs, NI in particular. Nice but
very expensive still.
Multi Cores help but still Windows
is there.
Around Windows XP time, Microsoft
and Intel decided to close the computers up and make plug in
boards a thing of the past. New busses were introduced, USB the
main contender and DAQ took another turn.
The reason for the closed PC
idea, was support calls were often all about plug in boards issues.
Most simple DAQ today is done
with USB cables connecting external DAQ boxes to a PC.
PCIe and PCI boards are available
but most people shy away, as it requires opening the PC box up
to install.
If the PC or DAQ boards fail
in service the technican has to open the PC and then all sorts
of issues can arise.
With USB, just unplug the broken
PC or DAQ device and reconnect and the system is alive very quickly.
So we now have a enormous range
of USB DAQ models and types. Everything needed to build sophisticated
DAQ systems.
They are so good I personally
have not used a plug in DAQ board for many years now.
We have all just adapted our
software around all these technology changes.
DSP and DSP+DAQ
combo + FPGA Techology
The lead company is Sheldon.
This company has been at the forefront of DSP and DSP+DAQ for
2-3 decades and even allow LabVIEW code to be run directly on
the DSP boards with no OS in the way. Yes amazing. This allows
building true real time DAQ and DSP/FPGA together in a PC.
GPIB - IEEE-488
Products
GPIB is all about
T&M, ATE and DAQ.
This technology
allowing the connecting of programmable instruments to computers,
was released in the late 60's by Hewlett Packard and originally
was called HPIB.
It was a giant
step in technology at the time and nothing even now has surpassed
it for easy of use and built for purpose, not even technologies
like Virtual Instruments in VXI, PXI and LXI.
In the late 80s,
when virtual instrumentation was released by NI with LabVIEW,
the interface method of chose for building quality Test (T&M),
Automatic Test (ATE) and DAQ, was still the GPIB or IEEE-488
method for most.
In 1975, when
the IEEE convened the 488th committee, HPIB became the GPIB and
the spec for it was IEEE-488.
HPIB = Hewlett
Packard Interface Bus
GPIB = General Purpose Interface Bus
The European edition is the IEC 60625-1
If you now read
several Blogs on Building Test systems, you will find many engineers
world wide, still prefer GPIB for their medium to large scale
Test systems, over newer technology.
The reason is
it works and well and allows for very high speced instruments
to be inserted into a Test system easily. Having instruments
that are stand alone in their own right, allows a great deal
of hands on playing and measurement method trialing with each
instrument, as the tests methodiology is developed. The outcomes
from this intimate playing with the instruments and Unit Under
Test (UU) is then translated into commands for the instrument
and embedded in the software. Very nice.
Since 1975 when
the IEEE-488 standard was released it has gone through many revisions
and upgrades and additions. IEEE-488-1978, IEEE-488.1, IEEE-488.2, SCPI, etc
with VISA added + Instrument drivers, have made the software
development process so much easier and faster. For instance LabVIEW
comes with hundreds of specific drivers for GPIB and other programmable
instruments.
The great thing
now that has developed is the melding of all Programmable instruments
into a Standardised Programmable Command Sets as a Composite
Test Instrument standard.
Instruments with GPIB, RS-232, USB or Ethernet, all run on the
same drivers. This means they are Bus and Instrument manufacturer
independent.
Instruments are
broken up into groups and commands for scopes from Agilent also
work with Tek etc etc. This means you can swap out a scope and
replace with another manufacturers scope and your test set will
still work. ( As long as the instrument specs are same or similar)
You can thank
all those committess from 1975 onward for amassing this huge
technology into an easy format.
Our lead company
for GPIB Interfacing is ICS of CA, with National Instruments
and Adlink close behind. It seems compatibility with NI and Agilent
is across all interface manufacturers.
There is also
a large expanding range of GPIB development software tools, not
only for LabVIEW & Measurement Studio ( From NI ) but also
in VB, .net, C, C++, C# and most other prgramming methods + instrument
drivers in those formats also.
Some LabVIEW
info for this issue.
LabVIEW OOPs.
Here is the link,
it may amaze you
Next month Quick
Drop
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