title: Need help understading sending bytes to serial port
body: <p>I am building this C# application which should turn a relay. It has a USB to serial port.
  The manual says:</p>
  
  <blockquote>
    <p>Module can receive single byte from upper monitor ( baud rate 9600)：</p>
  </blockquote>
  
  <pre><code>Upper Monitor                   0x50            0x51
  ICSE012A                                0xAB
  ICSE013A                                0xAD (This is the one i have)
  ICSE014A                                0xAC
  </code></pre>
  
  <p>Module will turn to normal work state after receive <code>0x51</code>. Then every data byte will control the relay directly . Each bit controls a relay ( <code>0</code> mark start , <code>1</code> mark stop ) . Read following for details:</p>
  
  <pre><code>Bit: 0 // Controls relay 1
  Bit: 1 // Controls relay 2
  </code></pre>
  
  <p>So to start the relay I should use: <code>This.SerialPort1.Write(0x51)</code></p>
  
  <p>But then I want to start relay one what do I put in? How do I understand this?</p>