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I would like to switch on a relay using a PCI-7250 NuDAQ card using .NET.

I know that the code in VB to turn on is:

card = Register_Card(PCI_7250, 0)

v = DO_WritePort(card, 0, &O17)

and to turn off:

v = DO_WritePort(card, 0, &O0)

I need to migrate this to C# code. Can anyone help me out with this?

dtb
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user965767
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1 Answers1

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If you want to go the way of reading/writing I/O ports, you need to be able to write them. The .net framework (the microsoft one on windows atleast) does not support this directly. For reading/writing to parallel ports i'm having great success with the InOut32 library (link). This means you will have to use PInvoke to make it work. For me this code works:

    [DllImport("inpoutx64.dll", EntryPoint = "Out32")]
    private static extern void OutputImpl(int adress, int value);

    [DllImport("inpoutx64.dll", EntryPoint = "Inp32")]
    private static extern int InputImpl(int adress);

    public static void Output(int adress, int value)
    {
        // I use this wrapper to set debug breakpoints so I can see what's going on
        OutputImpl(adress, value);
    }

    public static int Input(int adress)
    {
        int ret = InputImpl(adress);
        return ret;
    }

Note that if you are running a 32 bit application you will need to referrence the "InOut32.dll" library. I am unsure about the specific ports you need to use, but I imagine you can either find them on the internet, or give it a few tries some from your PCI cards configured IO address range (see the deveice's properties in the device manager).

Captain Coder
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  • Thanks! That was very helpful. I was wondering if you could tell me which pins would be turned on with the command v = DO_WritePort(card, 0, &O17). And what would happen with the command v = DO_WritePort(card, 0, &O0). The program I am developing now takes integer inputs. Example: if I input 15, pins 1-4 will turn on. I can't seem to decipher which pins these 2 commands will affect. Thanks! – user965767 Nov 16 '11 at 19:05
  • Notice that decimal 15 == 0x0f (C hexadecimal notation) == &H0f (vb hexadecimal notation) == &O17 (vb octal notation). So I would imagine that writing &O17 will turn on the lowest 4 data pins. I had a look on the manufacturer site, they don't seem to provide a low level specification, but I can't imagine it would be more complex than writing to an IO port to turn relays on or off. You just have to make sure to set the proper bits in the register you write. – Captain Coder Nov 17 '11 at 09:35
  • I had an extra look on google. There is a manual (http://www.web-tronics.com/pdf/LPCIe-7250_manual.pdf) that details the operation. Look at page 30 (page 38 in the pdf), it details the operation of the IO range (which is indeed just flipping a bit for each relay), also if you have more option boards installed. It also details what data you can read back, and what the different bits mean. – Captain Coder Nov 17 '11 at 09:47
  • Really great. I didn't bother searching StackOverflow because I figured my PCI-7520 hardware was too obscure. Instead, I resigned myself to looking for general-purpose inp/outp support in C#. Then somehow I ended up here; not only did the InOut32 library mentioned here work trivially and immediately, but the OP actually has my same obscure relay card. – Glenn Slayden Jan 04 '15 at 00:40
  • @GlennSlayden: Bro can you share how you acheived this. I'm on the same boat and want to learn how to achieve this through C# – user726720 Oct 19 '21 at 10:05