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Failure of Pics.

J

Jamie

Jan 1, 1970
0
we have some control electronics that employ pics in an industrial
environment.
The other day we found out something interesting, we installed
a mini board with a pic, on a rotating item of a machine.
made sure everything was secure etc. this unit does spin kind of
fast. mostly made from Aluminum and employs slip rings to supply
the hub with its power and signal return.


for what ever reason, after a few hours of spinning, the PIC
gets corrupted software and has to be reloaded.

We are still looking at the reason why. We almost think the movement
is causing some electrical field generation that is effecting the pic.
 
E

Eeyore

Jan 1, 1970
0
Jamie said:
we have some control electronics that employ pics in an industrial
environment.
The other day we found out something interesting, we installed
a mini board with a pic, on a rotating item of a machine.
made sure everything was secure etc. this unit does spin kind of
fast. mostly made from Aluminum and employs slip rings to supply
the hub with its power and signal return.

And is that supply filtered 'after' the slip rings ?

Graham
 
J

Jamie

Jan 1, 1970
0
Eeyore said:
Jamie wrote:




And is that supply filtered 'after' the slip rings ?

Graham
I really wasn't looking for an answer from you because I
know you're just digging.

Of course the line is filtered (DC-DC isolated). In any case, We ran
it with an on board battery pack which is good for hours. That didn't
solve anything. The output is isolated via optical coupling btw.
The problem is totally in the fact that it spins fast. We have
it sit there for hours idle or run a job where it spins very slow and
its find. Run a job at high RPM's it may not last 2 days. And we have
deduced that it's accumulated time. In other words. lets say it runs
high RPM's 10 hours, and we know it fails 20 hours total. , we can shut
it off. and run another job later at high RPM's for another 10 Hours and
good chance of failure again.
This does not cripple the process, it just disables a sensor that
they can get by with out.
In any case, I'm thinking that maybe static is being built up on that
part of the machine due to the nature of what that part does.
It pulls off a mylar tape from a pad that is used as a wrap on cables.
The sensor is a tension and break monitor.
 
D

Donald

Jan 1, 1970
0
Jamie said:
I really wasn't looking for an answer from you because I
know you're just digging.

I was going to ask the same thing.

Without asking questions, how can anyhone help ?
Of course the line is filtered (DC-DC isolated). In any case, We ran
it with an on board battery pack which is good for hours. That didn't
solve anything.

So after 10 hours, with a battery then the PIC died ??


The output is isolated via optical coupling btw.
The problem is totally in the fact that it spins fast. We have
it sit there for hours idle or run a job where it spins very slow and
its find. Run a job at high RPM's it may not last 2 days. And we have
deduced that it's accumulated time. In other words. lets say it runs
high RPM's 10 hours, and we know it fails 20 hours total. , we can shut
it off. and run another job later at high RPM's for another 10 Hours and
good chance of failure again.
This does not cripple the process, it just disables a sensor that
they can get by with out.
In any case, I'm thinking that maybe static is being built up on that
part of the machine due to the nature of what that part does.
It pulls off a mylar tape from a pad that is used as a wrap on cables.
The sensor is a tension and break monitor.

I doubt that static know the difference between 10 or 20 hours.

Maybe the sensor input is not protected well enough.

Is the PIC input connected directly to the tape detector ??

Yes, this is an Interesting Problem. (tm)

I have a Brother printer that can not print a second side, immediately
after the first side is printed. ( I have to flip the paper then print
the second side)

Pages get stuck together by static. I stretched a piece of foil garland
inside the paper tray. Helped for a while, but the garland gets pulled
apart inside the tray.

don
 
B

big.rad.maps

Jan 1, 1970
0
Two options, both based on trying to identify the reason for failure
while suspecting external static discharge:

1) mechanically disconnect the sensor from the point it would pick up
some static and see if the system would keep running at high RPMs
without the static from the tape
2) try some back to back 5 V zener diodes across the sensor inputs and
to ground, just to see if there is an abnormal input signal that needs
to get shunted to ground. Again run at high RPMs to test functionality
 
T

Tim Williams

Jan 1, 1970
0
Electrons have mass. You're spinning it fast enough that they centrifuge
out of the flash ROM.

:^)

Tim
 
we have some control electronics that employ pics in an industrial
environment.
The other day we found out something interesting, we installed
a mini board with a pic, on a rotating item of a machine.
made sure everything was secure etc. this unit does spin kind of
fast. mostly made from Aluminum and employs slip rings to supply
the hub with its power and signal return.

for what ever reason, after a few hours of spinning, the PIC
gets corrupted software and has to be reloaded.

We are still looking at the reason why. We almost think the movement
is causing some electrical field generation that is effecting the pic.

I believe it maybe gravity waves that's causing the problem.
 
C

colin

Jan 1, 1970
0
Jamie said:
we have some control electronics that employ pics in an industrial
environment.
The other day we found out something interesting, we installed
a mini board with a pic, on a rotating item of a machine.
made sure everything was secure etc. this unit does spin kind of
fast. mostly made from Aluminum and employs slip rings to supply
the hub with its power and signal return.


for what ever reason, after a few hours of spinning, the PIC
gets corrupted software and has to be reloaded.

We are still looking at the reason why. We almost think the movement
is causing some electrical field generation that is effecting the pic.

what G force is it subjected to ?

Colin =^.^=
 
S

Spehro Pefhany

Jan 1, 1970
0
we have some control electronics that employ pics in an industrial
environment.
The other day we found out something interesting, we installed
a mini board with a pic, on a rotating item of a machine.
made sure everything was secure etc. this unit does spin kind of
fast. mostly made from Aluminum and employs slip rings to supply
the hub with its power and signal return.


for what ever reason, after a few hours of spinning, the PIC
gets corrupted software and has to be reloaded.

We are still looking at the reason why. We almost think the movement
is causing some electrical field generation that is effecting the pic.

Probably a design flaw. Find a consultant (local, preferably) to
efficiently solve your problem. There are probably other latent issues
which perhaps can be found in time.


Best regards,
Spehro Pefhany
 
T

Tim Shoppa

Jan 1, 1970
0
we have some control electronics that employ pics in an industrial
environment.
The other day we found out something interesting, we installed
a mini board with a pic, on a rotating item of a machine.
made sure everything was secure etc. this unit does spin kind of
fast. mostly made from Aluminum and employs slip rings to supply
the hub with its power and signal return.

for what ever reason, after a few hours of spinning, the PIC
gets corrupted software and has to be reloaded.

We are still looking at the reason why. We almost think the movement
is causing some electrical field generation that is effecting the pic.

Flash-based PIC? Low-voltage programming still enabled?

Have you used flash-based memory microprocessors in similar slip-ring-
supplied devices?

I suspect that a ground opened up and the noise and hash on the other
lines got interpreted as programming commands.

Tim.
 
J

Jamie

Jan 1, 1970
0
Tim said:
Flash-based PIC? Low-voltage programming still enabled?

Have you used flash-based memory microprocessors in similar slip-ring-
supplied devices?

I suspect that a ground opened up and the noise and hash on the other
lines got interpreted as programming commands.

Tim.
We're using a DC-DC (isolated) . Think we may have it down to a static
build up due to the nature of the operation.
 
S

Spehro Pefhany

Jan 1, 1970
0
This unit works fine if the machine is operating at low speeds. High
speeds seem to cause failure after a few hours of operation.

I don't know if your reply was a derogatory one in nature, if so,
it would be nice to keep them to your self.

No it wasn't particularly. It just sounds like something that could be
found in a relatively short time by someone with a lot of relevant
hardware experience, and your guesses lead me to think that it would
be more efficient to get help, and we're not going to be able to help
much from a ng, most likely.
This was just a general
request incase some one had some experience using these devices in
high vibration or G-Force environments.

They are used in zillions of such applications. The problem is NOT in
the microntroller chip... it's SOMEWHERE in YOUR application. Maybe
mechanical, maybe a floating input, maybe passive component behavior,
maybe EMI, maybe triboelectric effects, who knows? Maybe just the unit
you are testing now is defective. There are even more possibilities
that come to mind.
I may try out a small AVR Uc, I've used those also for a numerous
of things.

I would suggest getting to the bottom of whatever is causing it. What
you don't understand generally comes back later to bite you on the a**
at a most inconvenient time.

Best regards,
Spehro Pefhany
 
J

Jamie

Jan 1, 1970
0
Spehro said:
Probably a design flaw. Find a consultant (local, preferably) to
efficiently solve your problem. There are probably other latent issues
which perhaps can be found in time.


Best regards,
Spehro Pefhany
This unit works fine if the machine is operating at low speeds. High
speeds seem to cause failure after a few hours of operation.

I don't know if your reply was a derogatory one in nature, if so,
it would be nice to keep them to your self. This was just a general
request incase some one had some experience using these devices in
high vibration or G-Force environments.
I may try out a small AVR Uc, I've used those also for a numerous
of things.
 
J

Jamie

Jan 1, 1970
0
Donald said:
I was going to ask the same thing.

Without asking questions, how can anyhone help ?



So after 10 hours, with a battery then the PIC died ??


The output is isolated via optical coupling btw.



I doubt that static know the difference between 10 or 20 hours.

Maybe the sensor input is not protected well enough.

Is the PIC input connected directly to the tape detector ??

Yes, this is an Interesting Problem. (tm)

I have a Brother printer that can not print a second side, immediately
after the first side is printed. ( I have to flip the paper then print
the second side)

Pages get stuck together by static. I stretched a piece of foil garland
inside the paper tray. Helped for a while, but the garland gets pulled
apart inside the tray.

don
well, You may think it's strange how ever, in the past the operator
claim to get static shocks when reloading the pad spindle. the catenary
arm for the tension monitor is connected to small string pot. the
string is a stainless steel type. and the pot is an optical variety so
that we can get long life. It outputs 0..10 volts with a 24 volt supply.

Over all, it actually works perfect. and as soon as we find out why
we're getting failures. We can solve this issue. This design will be
used through out our other locations that have the same type of equipment.
I'm going to reposition all the electronics in a different location
of the spindle. I think that'll take care of the static issues.
 
M

Michael A. Terrell

Jan 1, 1970
0
Jamie said:
This unit works fine if the machine is operating at low speeds. High
speeds seem to cause failure after a few hours of operation.

I don't know if your reply was a derogatory one in nature, if so,
it would be nice to keep them to your self. This was just a general
request incase some one had some experience using these devices in
high vibration or G-Force environments.
I may try out a small AVR Uc, I've used those also for a numerous
of things.


You think too highly of yourself. You need help, or you wouldn't
have asked. He gave you good avdice, then you shit on him. Typical.



--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
J

Jamie

Jan 1, 1970
0
Michael said:
You think too highly of yourself. You need help, or you wouldn't
have asked. He gave you good avdice, then you shit on him. Typical.
One should not throw stones at glass houses.
 
W

whit3rd

Jan 1, 1970
0
The other day we found out something interesting, we installed
a mini board with a pic, on a rotating item of a machine.
for what ever reason, after a few hours of spinning, the PIC
gets corrupted software and has to be reloaded.

Two possibilities: rotating wiring in a magnetic field gets induced
currents,
have you tried soft-tinned-steel shielding? And, is there a quartz
crystal in
the circuit? Stresses on a piezoelectric crystal can change the
oscillator
characteristic, or vibrations can cause spurious output. An LC
oscillator
should be easy to substitute in.

There are also piezoresistive effects in stressed silicon, but that
can only be
fixed by redesign or mechanical isolation (potting?) of the whole
thing.
 
F

Fred Bloggs

Jan 1, 1970
0
Jamie said:
we have some control electronics that employ pics in an industrial
environment.
The other day we found out something interesting, we installed
a mini board with a pic, on a rotating item of a machine.
made sure everything was secure etc. this unit does spin kind of
fast. mostly made from Aluminum and employs slip rings to supply
the hub with its power and signal return.


for what ever reason, after a few hours of spinning, the PIC
gets corrupted software and has to be reloaded.

We are still looking at the reason why. We almost think the movement
is causing some electrical field generation that is effecting the pic.

Well if it is an industrial environment and there are strong EM fields
in the immediate vicinity, spinning the part at large velocity through
both types of fields induces voltages and currents throughout the entire
IC and every other node on your circuit board. Depending on the type of
memory you have, this could certainly translate into accumulated time
causing memory cell corruption. The answer would then be strict high
attenuation EMI shielding, both magnetic and electric, a steel box,
filters on all I/O.
 
J

J.A. Legris

Jan 1, 1970
0
we have some control electronics that employ pics in an industrial
environment.
The other day we found out something interesting, we installed
a mini board with a pic, on a rotating item of a machine.
made sure everything was secure etc. this unit does spin kind of
fast. mostly made from Aluminum and employs slip rings to supply
the hub with its power and signal return.

for what ever reason, after a few hours of spinning, the PIC
gets corrupted software and has to be reloaded.

We are still looking at the reason why. We almost think the movement
is causing some electrical field generation that is effecting the pic.

Just curious: how many RPM and at what radius?
 
J

Jamie

Jan 1, 1970
0
whit3rd said:
Two possibilities: rotating wiring in a magnetic field gets induced
currents,
^^^^^^^^^^^^^^^ Very Possible ^^^^^^^^^^
We have a fabricator on the machine as we speak repositioning the
deck that houses the electronics. There is a DC drag clutch very
close by. And after some testing, we found it to get a heavy drive
of current at higher RPM's to maintain tension.
have you tried soft-tinned-steel shielding? And, is there a quartz
crystal in
No quartz, using an RC osc based PIC.
the circuit? Stresses on a piezoelectric crystal can change the
oscillator
characteristic, or vibrations can cause spurious output. An LC
oscillator
should be easy to substitute in.

There are also piezoresistive effects in stressed silicon, but that
can only be
fixed by redesign or mechanical isolation (potting?) of the whole
thing.

I hope we don't have go that route.
We'll see. Thanks.
 
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