controlling a laser shutter

[negres]

Hi
I would greatly appreciate your help with , I believe, a simple application.
I am a new user of labview. My problem is the following: I want to control a laser shutter, basically to open it by applying a voltage in excess of 4 VDC. I would like to do this following a trigger (TTL at 10 Hz) from a laser, and keep the shutter open for a certain time, 1 pulse every 100 ms.
Does anybody have this application already made in Labview? I have a M-series DAQ board and a BNC-2110 connection board.
Thanks in advance for any help you can offer.
Raluca

[DBM]

Hi Raluca,

I've done something similar with an E-series card, but I'm not sure I understand your setup. You have a train a pulses coming in at 10Hz, so for each pulse you need to open the shutter a certain amount of time? Then that amount of time would be less than 100ms?

The best thing would be to upload a picture of your timing diagram, then it may be easier for others to help.

[negres]

Thanks,
here is a timing diagram.
The laser rep. rate is 10 Hz (trigger) and want to open the shutter for 100 ms, after the trigger (about 50 ms) and let only one pulse go thru. Or more than one pulse if open for longer than 100 ms.
Then, a different operation, is reducing the rep. rate to 5 Hz, letting every other pulse go in a continuos manner. The program should stop when I tell it to.

[DBM]

It looks to me like you have about three options:

1. Look under "Examples" / "IO Interfaces Examples" / "DAQ Examples" / "Digital Input and Output" / "Buffered Pattern I/O" / "Buffered Pattern Output with Start Trigger"
You can load the buffer with 0-1-0 to activate and deactivate the shutter. The example works only once. If you want it to work until you press Stop, wrap a while loop around "DIO Start and DIO Wait"

2. Since your timing is not very critical and you may not want to deal to trigger setup, you could poll one bit (laser trigger) and activate another bit (shutter). Take a look at the attached vi.

3. You could use a couple of 555 chips and a simple circuit to build this in hardware (but that's for another forum).

[negres]

Hi DBM
thanks for the help but I am afraid I don;t understand it.
First, I can't find the example you refer to. Can you please give more details?

The DIO port read works with any card? I have an M-series DAQ and try to set up using the DAQ assistant.
I would like to use BNC cables coming into the BNC-2110. Where do I connect? I have never worked with digital ports before. It looks like the digital ports have to be wired in or use some special connector.

Thanks much for more ideas.
Raluca

[DBM]

The example I referred to should come standard with LabView. I've also attached with this message.

DIO Read SHOULD work with M-series cards but since I don't have one I can only confirm that it works with E-series cards.

It looks like the BNC-2110 is just an interface to the M- and E-series cards. Just an easy way to cleanly connect to these DAQs.