西门子S7-300编程，主要是S7-300和S7-400的梯形图(LAD)编程 参考手册，包含相关指令和说明。(Siemens S7-300 programming, mainly S7-300 and S7-400 trapezoidal diagram) programming reference manual, including related instructions and instructions.)

西门子PLC step7-300、400的解密程序(The decryption procedure of Siemens PLC step7-300 and 400)