title: What are the low level protocols used by Micrologix PLCs?
body: <p>I am building an application in C# which needs to talk to a Allen-Bradley Micrologix PLC. I know about the InGear driver to talk to it. I've used InGear in the past to talk to the other Allen-Bradley PLCs, and so I know that licensing with them can present problems to me. </p>
  
  <p>What I want to know is: Are there any TCP or UDP based protocols for communicating directly with the Micrologix PLC? Obviously there must be something since InGear probably builds their protocol on some lower level protocol.</p>