I have a project including rs232 and ethernet communication. I will control linear actuator by using VNH5019 motor control shield and Arduino Mega. From remote PC, a command will send by using ethernet. Ethernet will be converted to RS232 by using MOXA serial to ethernet Converter. RS232 is converted to TTL by using waveshare converter. By using command from ethernet, the linear actuator will move. Actually, the command that will send will be determined other engineer. I dont know yet what will be using. How should I start to build the system. How can I control motor by interpreting command from ethernet ? Could you give some idea ? I am newbie about communication protocols, I have begun to work by the way.

 

That’s a lot of intermediate modules. Why not use an Ethernet module on the Arduino and just communicate via Ethernet directly? You could connect with a cable or wirelessly.

You could communicate via HTTP or TELNET. The former may require extra coding, to process, parse and pull out the transmitted dats. The latter will accept communication with less overhead, after creating a connection. Disclosure, I have used the latter technique but not on an Arduino.

 

Look up virtual serial port. The PC end just thinks it's talking to a serial port. The RS232-Ethernet happens automagically.
Effectively PC - Virtual Com Port - Ethernet - [Ethernet - Some box- Serial port] - [serial port + Arduino]