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 ?

[JRA]

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 ?Well, FraserD, this is quite an application! The one worry I would have is in part 3):

simulataneously read the data from the spreadsheet file at a real time rate, therefore not allowing an out-of-synch situation.

Are you running on Windows? The problem is that Windows could get interrupted while your VI is running and take process control away from LabVIEW at any time. The file reading will all be done by Windows, so this is critical. You have no way of knowing if this could happen, and it makes the simultaneous reading almost impossible.

I think that your best bet is with the RTSI connection. If this is even an option, you could synchronize two boards where Board 1 is acquiring and Board 2 is outputting what came from Board 1. This would need to all be
done by the hardware because once software becomes involved, the interrupt scheme will throw you off.

However, I noticed that you're using an RS232 port, so I don't know if information from the port needs to be part of the output described in step 3. If so, the RTSI scheme may not work. Let me know if this is a possibility.

[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 ?JRA,

Thanks for the reply. Since i posted the message i have considered ways of removing the serial interface. Building a PIC which can convert the RS232 to an analogue voltage may work and therefore allow me to use another channel on the DAQ card.

I read your idea about the RTSI synchronised playback, and part of it puzzled me. If i am to use the hardware to read the spreadsheet, does this not require using windows aswell - or can i load all the data sets to the DAQ card onboard memory first and read it out from there ?

[JRA]

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 ?Hey FraserD,
I think that's a great idea about removing the serial interface. Concerning the RTSI idea, what I meant to say was that you could transfer the input of Board 1 DIRECTLY to Board 2, wherein Board 2 would output this signal. There wouldn't be an intermediate file that it's written to and read from. You could do this in addition, but Board 2 would read directly from Board 1 via RTSI. I believe this should work better than reading the file for Board 2.