Internet based process control usage has grown in the past years. Industry field demands were behind this, and it ranges from factory, office and home automation to tasks simplifications and cost reduction. In this book a hardware interface circuit and a software system used to control the temperature and level of a liquid tank is described. The advantage of the designed interface circuit is its simplicity and low cost. The same can be true for the software system in which we used C and Java programs to accomplish the communication. Both C and Java can be obtained freely and the development cost could be small. C language has been used to communicate with the designed interface circuit due to its strength in low level operations and communication with ports and hardware. In Java we have used mainly the Servlet for communication between the Client and the Server, which is a new approach and more reliable approach than the CGI based method that has common problems of speed and data persistence. This book is useful for people and researchers working in the field of control, remote access and computer based control.