Error 200284

[Yin]

Hi, I'm still pretty new to labview and I've come across the error 200284 problem.  This problems seems to occur when I try to use triggering to synchronize my data acquisition tasks.  I've read the other posts about error 200284 and I really don't understand where and how I'm supposed to connect an external clock to my BNC-2110 or  BNC-2111.

What I'm trying to do is send a trigger which will be used to trigger several other external devices and at the same time, I want the DAQ to start acquiring data.  Here is what I have so far. 

[David S.]

Hi Yin -

So you want your DAQ device to generate a synchronization pulse that's used by both the AI task and external hardware?

KB 336EKTKD explains possible causes of error -200284.  Among them is, "a start trigger was never received". Looking at your block diagram, I think I see why:

You have two unrelated blocks of code executing here.  There's no control over when functions happen with relation to other functions.  As such, you could be generating the pulse before the AI task ever looks for it, or after it has already timed out.  You can use the error cluster to daisy-chain VIs and force them to execute in a specific order.  There are a few example programs that show how to coordinate multi-function setups with the DAQmx driver.  Here's an expanded view of where you can find them:

Also shown in the first picture is the fact that you haven't specified an external clock.  If you want to use an external sample clock, create a control or constant from that input on the DAQmx Timing VI, then tell it which pin to look at for the signal.  The BNC-2110 Installation Guide shows that there is a breakout connector for all the PFI lines (and a BNC connection for PFI0) on the connector block.  Simply pick the corresponding pin in your constant/control, then wire the clock signal to it.  (Remember to use a DGND pin for the negative wire if you're not using the BNC connector.)

Message Edited by David S. on 07-24-2007 12:36 PM

Message Edited by David S. on 07-24-2007 12:37 PM