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For a lot of the western world, April starts with an April "Fools'
Day". Probably a holdover from the days when Europe changed to the
modern Gregorian calendar causing confusion and foolishness as people
celebrated the new year out of synch with the "real" new year.
Rather than suffering with foolishness, I like Mark Twain's comment,
"This is the day upon
which we are reminded of what we are on the other three hundred and
sixty-four."
We are all
prone to the occasional error and it's good to be reminded that no one is
perfect. It's good to have a sense of humor when things don't go quite
as planned. Whether you are the victim f some foolishness or it's
your turn to be the fool - take a little time from your day to read through
this month's newsletter. You'll feel a whole lot better, be a little
smarter and have some interesting things to share with your
colleagues. Enjoy! |
| Small is Big |
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 I
know the title of this section sounds like a contradiction in terms, "Small
is Big" - but it's true! We've developed a high resolution,
precision absolute industrial encoder with a small mounting footprint.
Introducing our newest optical encoder, the L18. This encoder is only
1.8 inches (about 46mm) in diameter, but it has 13 bits ( 8192 counts) per
turn resolution. Since it is optically based, it has the precision to
be used in applications that demand high performance along with small size
and weight: semiconductor manufacture, robotics, and mobile antenna
positioning just to name a few. To learn more about this "good thing
in a small package", click on the picture, above and you can download a PDF
specification for this part.
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As an homage to the fools of April, I found a web site that include
foolish things said by famous people. To give you a taste, here are a
few morsels from the site. Reading through this is guaranteed to make you
feel like a genius.
Most of my cliches aren't original. - Chuck
Knox
Always go to other people's funerals, otherwise they won't
come to yours. - Yogi Berra
If your parents never had children,
chances are you won't either. - Dick Cavett
If only faces could
talk. - Pat Summerall
I don't diet. I just don't eat as much as
I'd like to. - Linda Evangelista
The world is more like it
is now than it ever has been before. - Dwight Eisenhower
More
foolish quotes . .
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Can You Solve This? |
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 There are all sorts of ways to
create and discover problems with encoder signals. This one was
actually uncovered in our repair department when an absolute encoder
was sent to us for evaluation. This was a single-turn 13 bit absolute
encoder with a gray code data format and an SSI (serial synchronous
interface) output. This type of output requires the customer to supply
a system clock pulse which is used as a timing device to "clock out" the
encoder data, one bit at a time. Since there is a serial communication
link between the host and the encoder, it is important to pay attention to
the timing diagrams. One other aspect of these types of
installations is that cable capacitance reduces the effective bandwidth of
the signal and can become a factor on installations with long cable
lengths. To improve noise immunity, both the data channels and the
clock signals are usually sent as differential pairs.
To test these types of encoder outputs in our repair facility, we use
an SSI to parallel output converter. This device generates its own
clock signal and then converts the incoming serial data stream to a parallel
word that we can examine on a multi-channel oscilloscope. While
testing the encoder, our technician noticed the encoder appeared
to counting backwards. Normally these encoders are configured to
count upwards for a clockwise rotation of the shaft. After double
checking the direction control bit for proper operation he retested and got
the same result as before. What could be going on?
Answer: This one was a subtle effect caused by reversing the
CLOCK+ and CLOCK - lines during testing. Examining the SSI timing
diagrams, this accidental reversal meant that the most significant bit (MSB)
was being clocked out one cycle later than it should have been. Since
the relationship between the MSB and the MSB-1 on a gray code encoder
establishes the direction of count, this explains his observed
results. Properly connecting the + and - CLOCK lines cleared up the
issue and showed that the encoder was operating
properly. |
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Computer Attack!
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There are an awful lot of clever and creative people out there with
just too much time on their hands. Thank goodness they use that time
to do what they do, because it enlivens things for those of us who are
otherwise too busy to "play" with our computers. If you click on the
picture at the end of this email, you'll be treated to an amusing drama
of the man vs machine variety. No need to touch your cursor -
just let it run. Be sure you have plenty of bandwidth to capture all
the fast and furious action. Don't worry if you miss something - at
the end of the animation there is a scene selection so you can replay the
parts you missed. Have fun!  | |
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I hope you had fund with this month's newsletter. I always enjoy
hearing your feedback. Contact me if we can help you work out a model
number, troubleshoot a problem, or just double-check a wiring diagram.
Consider us part of your team and let us know if we can be of help.
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Thanks for your time,
Scott
Orlosky
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email: Scott
Orlosky
voice: 805-968-0782
web: http://www.beiied.com
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