The paper presents a real-time system modeling and identification scheme for estimation of plant model parameters using a single asymmetrical relay test. A modified set of analytical expressions for unknown plant models under nonzero setpoint and non-negative relay settings is derived. Thereafter, the unknown parameters of three different stable plant models are identified as first-order plus dead time, overdamped, and critically damped second-order plus dead time. The well-known examples from literature are included to show the accuracy of the proposed method through computer simulations. Yokogawa distributed control system centum CS3000 is considered as a design platform for an experimental setup for the realization of asymmetrical relay feedback test. Finally, the transfer function models derived from successive identification of plant dynamics are compared with the literature through Nyquist plots.