ADInstruments Powerlab to Labview

[dzilber]

Hi,
 How would I go about having my hardware, Powerlab 4/25 EMG measuring device, send my signals to Labview, via USB? Do I need special drivers? If so, where can I find them? Can I use NI-VISA?
  
    Thank you,
     David

[Dennis_Knutson]

NI has no driver for that hardware so the first place to check is with ADInstruments to see if they have anything. USB instruments do require a driver. This is usually provided by the vendor and is often a dll that you can call. The vendor would have to provide information on the dll function calls and parameters. It is possible to create a VISA driver for USB. When yuo do this, you replace any driver that the vendor provides and then use USB RAW communication which is a much lower level protocol. This is not trivial and getting the information from the vendor on how to to use USB RAW is usually more difficult than getting information on their high level driver.

[dzilber]

Ok, so what questions would I have to ask technical support in order to make this happen? As far as I know, it seems to me that without the driver, I must use VISA. You mentioned that the vendords provide information on the dll function calls and parameters..how does this information help me? What exactly do I need to ask? Please elaborate, I am very new to this process.
  Thank you so far,
   David

[Dennis_Knutson]

Ask them for a programming api (application program interface). Tell them you want to use the hardware with software other than what they provide. If they have a dll, then it would consist of various function calls and you would need this list. Each function call has a set a parameters that you pass to the function and also use to get data back. For example, an A/D device might have a function for setting the sample rate. Call it SetSampleRate. The parameters you have to pass may be an int for device number and a floating point number for sample rate. The documentation for the function would be written something like SetSampleRate(int dev, float rate). If you do get this type of documentation, LabVIEW 8.2 has made it much easier to create the correct Call Library Function Node. This is the LabVIEW function you use to call an external dll.

[dzilber]

Is the programmign you mention within Labview, or some other language like C++? Would you consider this a long process? Do you feel it would be much simpler to rather have the software which came bundled with the hardware pass the data onto Excel in real time, and from Excel into Labview? This is my alternative option, but the problem with it is that there will be timing delays and, more than likely, it will require more processing power.

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@Dennis Knutson wrote:
Ask them for a programming api (application program interface). Tell them you want to use the hardware with software other than what they provide. If they have a dll, then it would consist of various function calls and you would need this list. Each function call has a set a parameters that you pass to the function and also use to get data back. For example, an A/D device might have a function for setting the sample rate. Call it SetSampleRate. The parameters you have to pass may be an int for device number and a floating point number for sample rate. The documentation for the function would be written something like SetSampleRate(int dev, float rate). If you do get this type of documentation, LabVIEW 8.2 has made it much easier to create the correct Call Library Function Node. This is the LabVIEW function you use to call an external dll.

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[Dennis_Knutson]

You could do this in LabVIEW. As I said, there is a function called the Call Library Fundtion Node.

Depending on the complexity, it could take a while to write and debug. Using the existing software would probably be more simpler but if you want to read an Excel spreadsheet as its is being written, there might be problems with that as well. For example, the other program may open it exclusivley and you would have to wait until the other program closes it. I now nothing about the other program or what your overall goals are so I am hesitant to recomend one way or another. First, see what the vendor has to say. Worry about which direction you want to take when you knwo whether they will even make their programming interface available to you.

[ConniS]

Hey, 

I am wondering what came out of the powerlab to labview project. I am new to labview and would like to bundle several measurements with it. I would like to buy an EMG/EEG amplifier that I can use via labview and haven't quit decided on a specific one on the other hand I might get a compactDAQ plus small preamplifier. 

All the best,

Conni