generating a digital trigger output on CH1 ( Low then High) for the USB 5133

[bermea]

Hi,

I would like to generate a digital trigger on the USB 5133 CH1, is this possible?  I have tried with the PFI 1 successfully however the trigger output is only 3.5V and I need 5V, because this trigger signal goes to a Pulser box that generates a signal and is recieved by the CH0 on the USB 5133. This setup works on the NI 5102 but due to discontinuation I am forced to try a new device.

[Matt_E. · Accepted solution]

Channel 0 and 1 are inputs only so you will not be able to use them to generate a signal.  All of our current digitizer products that are recommended for new designs use 3.3V CMOS logic levels for the PFI lines in output mode.  Your best bet for generating a 5V digital trigger would be to use an external buffer that can accept 3.3V CMOS levels as an input but is powered from 5V.  Here is one part that could work for you but there are many others:  http://www.onsemi.com/PowerSolutions/product.do?id=M74VHC1GT126DT1G  Adding a buffer in line with the trigger signal will add delay so you will need to make sure this is acceptable for your application.

Hope this helps,

-Matt

Message Edited by Matt E. on 10-06-2008 09:02 AM

[bermea]

Thanks for the help Matt; would you happen to know which digitizer is the direct replacement (no added hardware) of the NI 5102?

[Matt_E.]

Unfortunately there is not a direct replacement for the 5102.  The closest board in terms of basic specs is the 5132 which is a 50MS/s 8bit USB board nearly identical to the 5133 you are using.  The biggest difference between the 5132 and the 5102 is the sample rate and analog bandwidth.  Both of these specs are considerably higher on the 5132 compared to the 5102.  This can be a good thing if your signal has high frequency content such as fast edges but it can be a bad thing if you are trying to minimize noise on the measurement.  The 5132 has a selectable 20MHz noise filter that can help reduce noise by reducing bandwidth.  I would recommend comparing the spec sheets for these 2 digitizers to make sure that any differences are acceptable for your application.  If there was some other aspect of the 5102 that was critical to your application let us know what it is and we could try and find something that matches up.

-Matt