4 to 10 volts pulse on a 1428 acquisition card and IMAQ

[matane]

Hello all,

I would like to trigger a cameraLink camera (trigger externally) which requires a voltage of 4 to 10 volts, and 10 mA min.

Question : Is it possible to do this with the functionnality supported on the NI-1428 board and IMAQ C

Thanks !

André Bombardier

[RManion]

Hello,

From what I can tell, you are hoping to trigger your camera with the IMAQ board. The trigger requires at least 4 volts and 10mA.

The IMAQ 1428 can provide up to 15 mA on its trigger output line, but that current is not guaranteed to be over 4 volts. Specifically, when a board is outputting its maximum current, the voltage of that signal typically drops. However, the manufacturer will specify a voltage level which the board can maintain. In this case, our IMAQ 1428 will maintain TTL logic levels, and supply at least 2.4V.

Long story short, your best bet is going to be powering this trigger in another manner. The 1428 may still be a great way of triggering (especially if you are synchronizing your camera with some other action), but you will need to have a small amount of extra circuitry to provide enough power. I would recommend some kind of mosfet or transistor, in which the trigger line drives the base input (or gate for a FET). Its just a simple switching circuit that the trigger signal from the board allows a higher current to flow from the other power source.

Hope this helps!

Robert Manion
Applications Engineering
National Instruments

[matane]

Hi Robert,

yes thats exactly what I am trying to do. I realize that the voltage from the 1428 board is 0 - 5 volts (TTL). The voltage to trigger the camera (DuncanTech MS3100) is 4 - 10 volts.

This camera can also be triggered via the Frame Grabber. Therefore, as you suggest, instead of triggerring the camera externally, I should try triggering it using the 1428 board, which I assume adheres to the Frame Grabber's implemented signal 0-5 v (which ever board is connected to it).

To do this I will do the following :

1- Set up my camera in Trigger Mode, and the source of the Trigger for the camera specified as 'Frame Grabber'.

2- Set up a Triggered Acquisition on IMAQ using : imgSessionTriggerConfigure2 to configure an external line that will receive a TTL trigger (from an independent system) which indicates a photo acquisition time (epoch).

3- Set up an external Trigger to be driven on a second Trigger line using : imgSessionTriggerDrive2 which will activate another external system, synchronized as accurately as possible to the IMG_FRAME_START signal of the frame grabber (NI-1428). I assume that IMG_FRAME_START and the actual time of integration of the frame (photo) are separated by the integration time.. ? The actual sych signal I wish to synchronize on is the Start of Integration of the Frame (which should be separated by only the integration time.. ?)

The design is not yet implemented, but I assume it should be a valid alternative to triggering the camera directly. If you have any comments, please let me know. Thanks for your reply.

André Bombardier