International Standard for PLC Programming Language

IEC 61131 is an international standard for plc. Parts 1 to 4 of the IEC 61131 standard were released from 1992 to 1995. my country released GB/T15969-1/2/3/4 (equivalent to IEC 61131-1 in November 1995) /2/3/4). IEC 61131-3 is widely used in PLC, dcs and industrial computer, “software PLC”, numerical control system, RTU and other products.
Five programming languages ​​are defined
1) Instruction list IL (Instruction list): Siemens calls it STL.
2) Structured text ST (Structured text): Siemens calls it Structured Control Language (SCL).
3) Ladder diagram LD (Ladder diagram): Siemens abbreviated as LAD.
4) Function block diagram FBD (Function block diagram): It is called function block diagram language in the standard.
5) Sequential function chart SFC (Sequential function chart): corresponding to Siemens S7Graph. the