This computer controlled coupled liquid tanks system can be used for investigation of different linear and nonlinear control techniques. A typical system consists of a personal computer, an I/O card, three coupled tanks, a variable speed pump, a flow meter, a PWM power amplifier, level measurement instrumentation, a power supply unit and number of tests and control programs. Introductory manual provides inofrmation about the system model, digital controllers such as PIS type, optimal state and fuzzy logic, etc. can be implemented on this system Provided flexible software minimizes the need for external test equipment.