title: USB Relay unit programming
body: <p>Never did any kind of embedded or hardware programming, I mainly deal with web applications.  But we have the need to turn off / on a usb relay possibly in C#.  I obtained a PDF of the device we are buying <a href="http://www.sigma-shop.com/manuals/usb_one_relay_box_manual.pdf" rel="nofollow">here</a>.</p>
  
  <p>In the document there is some sample code such as:</p>
  
  <pre><code>private void button1_ON_Click(object sender, EventArgs e)
  {
  serialPort1.Write(new byte[] { 0xFF, 0x01, 0x01 }, 0, 3);
  }
  private void button1_OFF_Click(object sender, EventArgs e)
  {
  serialPort1.Write(new byte[] { 0xFF, 0x01, 0x00 }, 0, 3);
  }
  </code></pre>
  
  <p>Question is, wouldn't I need a DLL / some sort of library to access <code>serialPort1</code>, sorry for the rubbish question but I'm just not certain how something like this works.  I am not seeing any indication from the pdf or the website about any sort of library I would need to reference.</p>