Ocean wave simulation

[ree]

I am using LabVIEW and a 6602 card to log data from my experimental rig (a wave energy converter).  I would like to use a new input to the rig.  This is going to be simulating a random ocean wave input.  The ocean wave simulation comes from an Excel spreadsheet (two columns time and wave amplitude (+ and -)).  To output to the machine that is going to input the ocean wave into the rig I need to change this Excel data into a 0 to 10V output.

I am hoping that I can add onto the existing data logging program the output to run the machine.  I have the 6602 card can I use this? I notice from the data sheet that it does have some outputs.  If not what do I need and can I easily modify my LabVIEW to output 0 to 10V from an Excel spreadsheet? Thanks 

[LV_Pro]

The "6602" appears to be a strictly digital I/O device. To output an analog (0-10V) you will need either a multifunction DAQ card, or some device that will convert your digital "words" to an analog level, basically a standalone D/A converter. The easiest path would be getting a multifunction DAQ with a sufficient analog output level. Keep in mind what the unit you are supplying the signal to requires. You say 0-10V, but does the source need to source current too, or is does the "device" just need a signal level? DAQ cards' analog outputs are really designed to produce "signals", not drive current hungry devices (motors, relay, etc.) directly. So you might still need some "buffering", usually a simple transistor circuit that will take your 0 - 10 V level and supply a 0-10V with current capability. Then with the DAQ card, you will just read in your file data, do whatever math is required to scale the numbers, and output it to the DAQ. It is a bit more complex that that, you will want to output the data at a rate that is appropriate, but that "is left for the industrious student" (a favorite quote from a less than favorite professor)

[ree]

Dear Putnam,

Thanks for your reply, I can confirm that the input machine requires just a signal, it gets its power from other sources.  So, I require a "multifunction DAQ card" and some labview code to scale the numbers and off I go?

Best wishes,

Robert

[LV_Pro]

Well, that is an over simplification, possibly. I don't know how you are currently logging the data, presume that some "sensor" gives you digital information, possibly digital "words", since you are using a purely digital I/O board, that are then saved as numeric data to a file. You wish to take this data, read it in and use it to actuate, I'm guessing, a wave generation in a test tank. How does that work? A physical position based on an input voltage level? You will have to consider not only position but velocity, or acceleration, to physically represent the motion represented by the input data. That is the "little math" that I was talking about. I had a similar project, where I had actual earthquake data, representing the actual seismigraphic data, and had to "translate" it into displacement commands, to run a "shake table" simulating the original earthquake. It is still a work in progress, although most of the stuff still being dealt with is more having to do with interfacing it to the web, it is a earthquake demonstrator at the Ithaca ScienCenter, in Ithaca, NY, USA.