title: How to get data from RS-485 connected by USB
body: <p>I need to read data from some Data Aggregator Device over RS-485 interface by USB port (USB-to-RS-485 converter used) for the Desktop App on JavaFX, so I have stacked on checking connection and getting proper values. </p>
  
  <p>Data Aggregator Device collects information about produced current, power etc. from PV-module (Solar Energy). This device has the only RS-485 port. As I read from a documentation, it uses Modbus RTU protocol (with settings: 9600-8N1). </p>
  
  <p>To be honest, It's my first experience with working on COM-ports and Devices. That is why I don't know even am I correctly connect pins. I read a lot of things related with RS-485, Modbus. But, still, I am on the first steps.</p>
  
  <p>So, I use simple UTP cable to connect. And what I have done:</p>
  
  <ol>
  <li><a href="https://i.stack.imgur.com/RzrLy.jpg" rel="nofollow noreferrer">This is how I connect USB-to-RS485 converter</a></li>
  <li><a href="https://pp.vk.me/c837628/v837628592/1dc37/d7NfEddewCE.jpg" rel="nofollow noreferrer">And this is
      about Data Aggregator Device</a></li>
  </ol>
  
  <p>Windows found virtual "COM3" port, after connecting USB to PC. Then I try to check connection with Terminal 1.9 by Bray. I try to send something. And as receiving messages it sent me some data also. However, it doesn't mean that everything connected well. Also terminal shows me some <strong>FRAME ERROR</strong>.
  I know, that Modbus protocol based on "master-slave" scheme. Therefore, PC as a client is "Master" and device as a server is "Slave". I have to send some request to the slave to get some expected response. But, how?!
   Please, check my connections! I don't know what to do next. </p>