How can I output a 5 volt signal after another signal stops?

[YellowstoneJJ]

Hello,

I have a high speed camera that requires a 100 microsecond, 5 volt signal to trigger.  I would like to trigger the camera when a break screen, carrying another voltage, tears and a voltage can no longer be carried through it.  I have a NI BNC-2110 to carry any signals to my break screen and camera.

So far I have been able to write a LabView program that uses an Express DAQ VI to create and output an analog voltage to my break screen.  I have another Express DAQ VI that reads a voltage signal from the other side of the break screen.  (So, when the break screen is not torn, the 2nd Express DAQ VI is reading the signal that is being output by the 1st Express DAQ VI, but when it is torn the 2nd VI reads nothing as it should).

I would like to send a 5 volt signal to my camera the instant that my break screen gets torn (when it no longer carries a voltage and the 2nd Express DAQ VI stops reading a voltage.)

I have been succesful in getting the 2nd Express DAQ VI to read a voltage when the break screen is not torn and also not read a voltage when the break screen is torn.  But I am very confused as to what my next step should be and have been very unsuccessful.

Am I on the right track?  Or should I be doing something else all together?

Thank you for all help,

JJ

[RavensFan]

What data acquisition card are you using?  BNC-2110 is just a connector block.  The type of data acquisition card will determine how and if the analog input signal can be used as a trigger for a digital output signal.  It will be a rather sophisticated setup and I doubt the Express VI's will have the flexibility you need to set it up.  You will probably have to use lower level DAQmx VI's.

[YellowstoneJJ]

Hi,

We are using a PCI-6115 data aquision card.  I hope this helps because I am stumped.

Thanks,
JJ

[YellowstoneJJ]

Attached is my current .vi block diagram.

[RavensFan]

That looks like a high quality guard.  The data sheet says it will do simulatneous sampling and can trigger off of digital and analog inputs.  I haven't done that myself so I don't know how to set up the lower level DAQmx functions.  Look in the examples for trigger and synchronization under the DAQmx examples.  Someone else who has done this before may be able to jump into the thread and offer the answer.

[hoffiz]

Hi,

When you say it reads nothing, I think you mean you read zero, right? It sound that you basically want to trigger (send the 100ms 5 Voltspulse) to the camera when the “break screen” is open and it can’t carry the voltage.  What is the voltage you read when the screen breaks? Can you post some picture of how the signal looks before and after the screen breaks?

I think you might be able to check for voltages levels and generate a pulse when your signal drops to zero or to whatever voltage it is dropping.

Waiting for your reply

[YellowstoneJJ]

Hi Jamie,

What I am trying to say is that I am generating a 1V analog signal from LabView to the break screen.  I then have LabView acquire the voltage signal from the break screen.  Then I have a LabView basic function signal generator producing the 5 Volt signal necessary to trigger the camera the instant the break screen is torn (but only on a waveform graph).  I cannot get LabView to actually output this 5 Volt signal from the analog output on my BNC-2110 connector to my camera.  Everytime I set it up for the output port on the BNC-2110, I get an error that the resource is already being used (Error 50103).

The first picture I have attached is where the break screen is not torn.  "Waveform Graph 2" is what I am outputing from Ao1 to the break screen.  "Waveform Graph" is what I am acquiring from Ai0.  "Waveform Graph 3" is the signal I am generating that is supposed to go to the camera, butI am having trouble outputing.

The second picture I have attached is where the break screen is torn, and "Waveform Graph 3" is showing a 5V signal.

Thanks for your help,

JJ

[YellowstoneJJ]

oops forgot the attachment pictures

[hoffiz]

Hi,

From your previous code “waveform graph 3” is not going anywhere so I guess you have updated your code. Causes of NI-DAQmx Error 50103 "The Specified Resource is reserved, this is a very good article that shows the possible reasons for this error. In your case I think is case 1.

I hope it helps