PXIe-8840 SMB trigger voltage/routing

[proland1121]

Hello,

I have a PXIe-1078 chassis with PXIe-8840 embedded controller (Win 7 OS) and PXIe-4137 SMU.  I need to acquire data for a window of time (trivial) while I trigger an external lamp supply (5V pulse trigger to a Xenon Flash Lamp power supply)

I configured the SMU to trigger on Software measure trigger (niDCPower configure software edge measure trigger.vi) and to route the Measure Trigger to the SMB trigger line of the 8840 (niDCPower Export Signal.vi) so I can trigger the flash lamp.  This approach was recommended by an NI employee when I was configuring the chassis, so I currently don't have any other modules I could use (digital I/O for example).

While my program is running, the SMB trigger behaves as expected.  I get a 250ns, 5V pulse out of the SMB trigger connection.

My problem is that when my VI is not running (say after turning on the chassis or closing the program) I get a DC 5V signal at the SMB connection.  This results in my flash lamp triggering as fast as it is able (capacitors take a few seconds to charge) which is a huge safety concern for operators.  Is there a way I can have the PXIe-8840 SMB trigger default to 0V instead of 5V or route to one of the PXI back-plane trigger lines?

[Dafrizzy]

Hey Proland,

Have you considered sending a low signal at the end of the VI to reinitialize the trigger line to 0V so that every time the VI has finished running, it should be at 0V instead of 5V?

[proland1121]

Hello Daniel,

That approach keeps the SMB trigger line low; so long as the VI is running.  As my PXIe-8840 runs Win 7 OS, there is a period of time between turning on the PC and starting software (initializing PXI modules).  It is during this time, which the SMB trigger is high and my system triggers uncontrollably.  I could get around this with an external safety switch, but I'd rather keep the system components to a minimum.

[lovelydevil7]

Hello Proland,

I'm doing the same thing recently.Have you had solved the problem?

But I'm a newcomer.Could you share your vi(niDCPower configure software edge measure trigger.vi)and(niDCPower Export Signal.vi)?

My email :  lovelydevil7@126.com

Thanks very much!