It has the higher switching speed and frequency and can be used as the pilot valve for a larger flow rate valve, or as a direct control valve for small flow rate hydraulic loop.

Direct control of hydraulic servo valve by means of PLC can simplify the control of hydraulic system and reduce cost.

The method of direct control of hydraulic servo valve by means of PLC, the component parts of the control system and the driving interface circuits were described mainly in this paper.