What is the benefit of real-time sample compression?
Real-time sample compression or "transitional sampling"
allows the LogicPort to utilize its sample buffer much more
efficiently. The data is first sampled, then compressed in
real-time using a lossless compression algorithm, then
written to the sample buffer. The sampled data remains compressed until the software
expands it back to its uncompressed form for display.
This
entire process is transparent to the user and has zero
impact on measurement accuracy, yet allows the LogicPort to pack
much more data into its sample buffer.
Compression is particularly effective for high-resolution
capture of high-speed bursts separated by long periods of
low or slow signal activity. That's because during periods
when signals have little activity, the LogicPort can
continue to sample at high speeds without filling its
sample buffer with thousands of copies of identical data.
Only meaningful data is stored in the buffer - memory
addresses are not incremented simply to mark time.
The degree of compression varies depending upon the nature
of the data, but typically ranges from significant to
dramatic. Our proprietary compression algorithm insures that
the LogicPort's compression feature never imposes a
performance penalty, regardless of signal activity or speed.
As a result, the LogicPort enjoys a significant advantage
over traditional transitional sampling systems which simply
assign half of all available memory locations as storage for
time stamps (thereby reducing the effective buffer depth by
half for very active signals). To see the LogicPort's sample compression in
action take a look at the
screenshots, or download the
free software
and explore the sample projects which are included. As you'll see, it’s not uncommon to
collect many times the size of the sample buffer. |
How many full-speed channels does the LogicPort support?
The LogicPort will simultaneously sample all 34 channels
with full buffer depth at 500MHz
in timing mode, 200MHz in state mode. This is in direct contrast with
competing products which sample at full speed on only a fraction of their available channels,
or with only a fraction of their marketed buffer depth.
When sampling in state-mode, one channel is used as a
state-clock input allowing the remaining 33 channels to be
sampled at the state-clock rate. |
Could I sample at 500MHz using an old 400MHz CPU and USB
1.1 port?
Yes! The speed of the PC's CPU and USB port have no relation
to the LogicPort's sample rate. The LogicPort can acquire
data at up to 17 gigabits per second (34 x
500MHz). This is much faster than any USB interface (even USB 3.0) can
transfer data. To achieve these rates, the LogicPort hardware
first acquires data in its internal high-speed memory at the chosen
sample rate, then stops sampling and transfers data to the PC
at a slower rate which USB can handle. Once the transfer is completed, the
LogicPort hardware begins a new acquisition while the
LogicPort software processes and displays the most recently
acquired data. This process is virtually identical to what
occurs in a stand-alone logic analyzer. The acquisition and
display functions are simply implemented in separate
enclosures. The speed of the PC's CPU only effects how fast
the software can process newly acquired data for
display. Running the LogicPort on a slow PC will reduce the number of times
the display is refreshed each second, but the sample rate
during acquisition will not be affected. When running on any modern PC
the displayed data can be refreshed 15-25 times per second, approximating a
real-time display similar to that of an oscilloscope. |
Can I use the LogicPort side-by-side with other
development tools?
Yes. The LogicPort does not "take over" your PC, and doesn't
require 100% of the available CPU or USB resources. It will
function normally along side other development tools and
Windows applications. |
How does the LogicPort connect to my circuit?
Each lead of the color-coded input probe supplied with the LogicPort has a female contact compatible with standard 0.025-0.030” round or square pins. Typically these leads are connected directly to
the headers
present on many circuit boards. The probe includes four ground leads
for optimal high-speed sampling. The LogicPort probe contacts
will also connect directly to grabbers such as the
EZ-Hook XKM, and Pomona 5360.
These grabbers have 0.025” pins designed for this purpose. EZ-Hook XKM grabbers are
identical to those supplied by Agilent (except for color and
logo), and are available in our online store. Pomona 5360
grabbers are available from Newark Electronics and others.
Another option is to connect the probe
leads directly to PLCC clips such as the 3M 923675-84 and DIP-clips such as the 3M 923690-40.
These clips are available from Digi-Key and others, and
allow direct connection to PLCC and DIP IC packages.
The LogicPort input connector is a standard
40 pin IDC compatible header. You can use inexpensive IDC connectors and ribbon cable to connect directly to a header on your circuit board, or to create your own custom test leads.
The 40 pin cables used with IDE hard drives make a good
starting point for custom test leads (be sure to keep them
as short as possible). |
Is there a Mictor adaptor available for the LogicPort?
Yes. We offer a
38 pin Mictor adapter
which has
pin and channel assignments directly compatible with those used by Agilent and Tektronix.
Our adapter has a 38 pin Mictor plug which mates with
Mictor receptacles such as the
AMP 5767096-1
and 2-5767004-2.
Mictors offer convenient, mechanically secure,
high-performance connectivity to target systems. Please contact Intronix
sales for purchase information. |
Can I export acquired data to another program?
Yes. The sampled data is stored in ASCII format, as comma-delimited values. You can import this data directly into programs like Microsoft Excel. |
Can I run the LogicPort from a bus powered USB hub?
Yes. As long as the current required by the hub plus all connected devices does not exceed 500 milliamps (per USB specification). The LogicPort’s low power consumption makes this condition easy to meet. |
Is it possible to use multiple LogicPorts for more
channels?
We do have customers using them this way, however It is only
practical to use multiple units in state mode, and only if
your circuit can provide a common clock and trigger signal
to all units. Cross triggering between units is not
possible. Each unit must have a separate instance of the
software installed and running. Please contact support for
more information if you plan to use multiple units. |
Have a question not answered here?
Ask us by emailing support@pctestinstruments.com. |
| |
Trademark Acknowledgement
|
| Intronix is
a registered trademark of Intronix Test Instruments, Inc.
USA. All other referenced marks, whether claimed
or registered, are for identification purposes
only and are the exclusive property of
their respective owners. |