The embedded PLC SPTK2023 and SPTK2024 were used as key units of electrichydraulic control system of the grab. One of PLC controller was master and the other was slave. The master controller drived the loadsensing proportional directional spool valve. Herein, two controllers, main control chassis and display terminal were mounted to make up a network based on CANOPEN bus, so that it could implement excavation and other work. The PLC controllers could acquire the outside ambient information and monitor the real time operating parameters, thus it guaranteed the failure warning and safety protection in the process of excavation operation.