为初学者接触西门子PLC和变频器通信的主要手册-。-The converter software is the Siemens equipment, such as Siemens USS protocol and communication procedures of the s7200.

主要描述页岩气中压变频系统的电路，该系统主要是为压裂泵电机进行变频驱动。-It describes cicuit in the medium voltage system of shale gas ,It primarily for fracturing pump motor by variable frequency drive.