How to 1)create a spreadsheet with data logging (commencing from a trigger given by a change in scene determined b

[FraserD]

y PCI-1409 and IMAQ function) at accurately (hardware) specified time intervals and then 2)read these values from the file, again at an accurately known rate (real time) in order to synchronise with the video being played through a PCI-1409 frame grabber ?The requirement here is to:

1) log data to file (one serial port RS232 input and 3 or 4 analogue input using a PCI-6024E. A header will also be produced and the file given a corresponding name)
The trigger to start the data logging will be given by a drastic change in scene and this will be provided by IMAQ functionality from a PCI-1409 frame grabber.

2) During the datalogging a video sequence is si
multaneously recorded on digital 8 format

3) Then it is necessary to recreate this DAQ situation by playing the video through a PCI-1409 IMAQ card and
simulataneously read the data from the spreadsheet file at a real time rate, therefore not allowing an out-of-synch situation. the same 'drastic scene change' will be used as the trigger.

A RTSI cable between the 2 boards exists, but i am struggling to accurately timebase all my measurements and synchronise the readback.

I am using win 2000 pro and LABVIEW 6.1

Any ideas ?

[Ben]

y PCI-1409 and IMAQ function) at accurately (hardware) specified time intervals and then 2)read these values from the file, again at an accurately known rate (real time) in order to synchronise with the video being played through a PCI-1409 frame grabber ?Hi FraserD,

You may want to re-post this question to the vision group where you may be able to get some suggestions on how to take advantage of the functionality of your frame grabber to get teh trigger you are after.

As far as I understand you may not be able to do what you are asking using the hardware and software you listed (that is why I suggested re-posting to the vision list).

What you described would be very "do-able" using LV-RT (where even the software timing can give you good determinism) in one of NI's PXI chassis'. In this case your time critical loop should check the frame grabber for a trigger condition and use that check to determine what to do with the data. Time stamping can be handled as an offset from a shared start time. The PXI system hav
e disks so you could queue up the acquired images and data to seperate loops that handle writting to disk when the time critical thread is not executing.

I will watch this question for the input from others in the hopes that I am wrong and may learn somthing in the process.

Ben