5V TTL Trigger noise with PCI-1428 board.

[crane]

Hi,
I use an example (LL Triggered ring without Timeout.vi ) and  give a  trigger signal to  RTSI0 Pin on PCI -1428 board.

Here is the hardware and software that I am using
JAI A10CL
PCI -1428 with NIIMAQ 3.1.1
LV 7.1
Camera link cable.

Counting is very important for me but  while  inspecting  40000~50000  times  I get  a  wrong image.
I think the grabber board aquire an image without trigger signal.
Because  when I check AC220V with Testmultimeter, Image counting number is incresing without trigger signal.
I checked Frame Ground and tried to attach a pull-up resister but it was in vain.

And please see the image file  attached, it shows how I make a trigger signal.
it's very simple I use only a photo coupler (PC817).

Do I have to attach a noise filter?
And what noise filter is effective?
Any suggestion would be appreciate!

Crane

[RManion]

Hi crane,

Let me check to ensure that I understand you correctly.  While acquiring 40-50 thousand images, you receive an image without having sent a trigger?

Unfortunately I have not encountered this problem before.  Does this happen consistently and are you able to monitor the trigger line?  If so, I would set up a test in which you can see the image is acquired without the board receiving a trigger.

If you are designing a filter for your trigger line, be sure to consider the period of your trigger, the frequency of the trigger, and the required rise time by the IMAQ board.  If you filter out too many high frequencies, the rise time for your trigger will be increased.  All this said, the best solution might be compensating in software, rather than in hardware.

Let me know how it goes or if you have any additional questions.

- Robert

[crane]

Thank you Robert !

I think you understood me correctly.
I receive an image without having sent a trigger.
And it happens very very irregularly.
Now I think the trouble comes from the other machin
because I have noticed it  while I stpped other machine(which is beside the camera) instantaneously.
( Solenoid valve, Motor noise, Relay coil noise, etc)
So I changed trigger line cable with thicker and shield cable.
And I connected the shield line to Frame Ground.(please see the image file attached)
I'm sure it decrease but can not solve the trouble completely.

So now I'm looking forward to finding EMI Filter.
I need more information about this
Please help me once more. thank you.
 

[AnalogKid2DigitalMan]

Do you have an oscilloscope to view signal/noise with? Does the 1428 have internal pull up resistors for the RTSI lines?

[RManion]

I agree with AnalogKid2DigitalMan.  If you have an oscilliscope, this will be the best way to detect where and when the incorrect pulses occur.  Use the scope to view the electrical signal on the trigger input.  You will be able to determine how noisy the signal is while also keeping an eye out for invalid pulses.

Good luck!

Robert

[crane]

Thank you for your advice..

Yes I checked  trigger line with oscilloscope and found abnormal signal.

And please see the image file  attached.

But I can not know where it comes from exactly and when it  happens.

Now I'm trying to remove this noise..

I'm in trouble because this system is  inspecting bank notes

It is fatal error  if  counting number is uncorrect....

  Please.. any suggestion would be appreciate!!!

[AnalogKid2DigitalMan]

I looked at the 1428 manual but could not find out if the RTSI lines have their own pull up resistors. Could someone at NI check into this? If there are none, I would suggest adding a pullup to the opto circuit.

Is there a reason you are using the RTSI line instead of the trigger inputs?

Is the noise present on the diode side of the the opto?

Where is the 5V on the diode side of the opto coming from, how long is the wiring there and what type? If noise in on the input side of the opto, it will get passed to the RTSI.

Good luck, let us know what you find.

[kellam]

The RTSI lines have weak pullups.  As AnalogKid2DigitalMan suggested, you should look at the input side of the the optocoupler.  Also, your glitch trace seems to indicate a pulse that goes > +5V.  If that is real, it is disturbing, as you have no power source over 5 volts.  You shouldn't be seeing that unless you have a > +5V power source, an inductor on the circuit, or you are picking up noise. 

-Jeff