title: Communicating via Modbus RTU over TCP/IP Protocol
body: <p>I'm trying to establish a connection with a device on my network and have 2 Modbus Protocol
  related questions:</p>
  <ol>
  <li>Is the protocol used by this controller &quot;Modbus RTU over TCP&quot; or &quot;Modbus TCP&quot;?</li>
  </ol>
  <p>Here is the device manufacturer's description describing the connection:</p>
  <p>&quot;To read and write data, port 10001 is used as a TCP/IP tunnel. This means the MODBus
  protocol is tunneled in RAW binaries through the XPort device. Only the MODBus
  telegram is sent to the controller.&quot;</p>
  <ol start="2">
  <li>Depending on the protocol, how should the client request to read/write be formulated?</li>
  </ol>
  <p>Assuming it's Modbus TCP I have written a simple code in Python to read a register by sending a Modbus request formated as shown bellow, I received no meaningful data.</p>
  <p><a href="https://i.stack.imgur.com/9hsVX.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/9hsVX.png" alt="MODBUS TCP/IP" /></a></p>