The stability and theoretical performance limits of the feedback controlled force reflecting haptic manipulator have been discussed. All the virtual environment which interact physically with the haptic system have its own stable performance limit. Three different realization of the interfaces have been compared using the driving point admittance. The haptic system which is separated from the human hand or finger is superior to its stable interaction provided that there is a means to apply a direct damping between the haptic manipulator and the human finger Electro-magnetic force is used for its digital implementation of the simple separated type haptic device. The stable limits of a virtual wall is calculated and experimental results show that there is performance limits in this implementation.