thoult
2007-08-07 17:10:13 UTC
Hi,
I am running a VI which triggers analogue input from an accelerometer on the first digital edge from a light sensor pulse, measured against the internal clock on the cDAQ chassis. However, the light gate occasionally re-triggers shortly after the first falling edge due to the rebounding of the probe that initially triggers it. I would like to re-configure the VI to prevent triggering after the first event, either for a configurable time span or until the user resets it via a control.
I have previously overcome this problem by comparing the calculated speed that the probe has passed through the light gate (by using the period of the pulse and the width of the teeth of the probe...) to a minimum speed, and discarding anything that is acquired from a trigger corresponding to that lower speed, but recently test conditions have resulted in rebound speeds that are comparable in size to the downwards speeds, so this is no longer useful.
Please find the relevant section of VI attached - I couldn't include the entire VI because it's huge! Instead I've just removed the section that acquires the digital pulses and the analogue input. Any thoughts or opinions are welcome.
I am using the following hardware - 9401 digital I/O module and 9233 IEPE analogue input module, both mounted on cDAQ 9172 chassis, with the 9401 in one of the PFI slots - and running LabVIEW 8.0 / 8.20, NI DAQ 8.0.
impact1.vi:
http://forums.ni.com/attachments/ni/70/7296/1/impact1.vi
I am running a VI which triggers analogue input from an accelerometer on the first digital edge from a light sensor pulse, measured against the internal clock on the cDAQ chassis. However, the light gate occasionally re-triggers shortly after the first falling edge due to the rebounding of the probe that initially triggers it. I would like to re-configure the VI to prevent triggering after the first event, either for a configurable time span or until the user resets it via a control.
I have previously overcome this problem by comparing the calculated speed that the probe has passed through the light gate (by using the period of the pulse and the width of the teeth of the probe...) to a minimum speed, and discarding anything that is acquired from a trigger corresponding to that lower speed, but recently test conditions have resulted in rebound speeds that are comparable in size to the downwards speeds, so this is no longer useful.
Please find the relevant section of VI attached - I couldn't include the entire VI because it's huge! Instead I've just removed the section that acquires the digital pulses and the analogue input. Any thoughts or opinions are welcome.
I am using the following hardware - 9401 digital I/O module and 9233 IEPE analogue input module, both mounted on cDAQ 9172 chassis, with the 9401 in one of the PFI slots - and running LabVIEW 8.0 / 8.20, NI DAQ 8.0.
impact1.vi:
http://forums.ni.com/attachments/ni/70/7296/1/impact1.vi