title: can devices with bluetooth 4.0 and 3.0 or older interact with 2.0+EDR i.e send the command to be executed and recieve the output produced?
body: <p>I want to communicate with a device with bluetooth 2.0+EDR type using a android device 
  i.e I need to send the command to it and get the output from that back to my device </p>
  
  <p>But the problem is i have doubt whether bluetooth versions after 2.0+EDR (2.1,3 and 4) can do this or i must use only the same type to do this... </p>
  
  <p>Are 3.0 and 4.0 backward compatible?
  and does backward compatible mean it can interact with all the older versions or a particular version??</p>
  
  <p>Please help.</p>