-In January 1968, Bedford associates, under the leadership of Richard Morley, developed a programmable controller to support ladder logic programming.
-In March 1968, GM (hydraulic transmission manufacturing division in Ypsilanti, Michigan) initiated the project of "standard machine controller".
-In June 1968, stone of General Motors drafted the technical specifications of the general controller, including: the controller should be modular structure, and be able to withstand the harsh conditions of electromagnetic interference, vibration, dust, humidity and so on. The IO interface supports multi-channel digital isolated input and digital output, and has scalability, data power down holding function and timing control function. Several companies have responded to GM's requirements and submitted prototypes.
-In October 1968, Bedford associates created a new company to promote the industrialization of new programmable controllers. The company name Modicon comes from the abbreviation of "modal digital controller". The new product is named Modicon 084.
-In June 1969, DEC company submitted pdp-14 controller to GM, which is based on pdp-8 minicomputer and extended IO design. The controller does not support user independent programming.
-3I company submitted PDQ II prototype controller to GM.
-In November 1969, Morley showed GM Modicon 084, which GM later used for production line control. Morley is widely regarded as the "father of PLC".
-In December 1969, Modicon submitted its first patent on PLC, digital computer industrial controller system and applications.
-In 1970, 3I submitted the second round of prototype PMC (programmable matrix controller) to GM.
-In 1971, Allen Bradley acquired 3I.
-In 1971, ODO Josef struger and Ernst dummermuth, engineers of Allen Bradley company, developed a new generation of controller to replace the former PMC. The model was bullet 1774 and named programmable logic controller (PLC). The special programming Terminal T3 was adopted. The structure applied for us patent us3942158. ODO Josef struger later became a member of IEEE and vice president of technology of Rockwell company. He made important contributions to Allen Bradley PLC architecture design and development of international standard of PLC programming language.
-In 1973, Modicon's Mike Greenberg and Lee Rousseau developed a new generation of controller Modicon 184.
-In 1977, Gould electronics acquired Modicon company. In 1980s, Modicon product line was sold to AEG company of Germany. In 1990s, Schneider company of France acquired Modicon product line.
-In 1977, Allen Bradley company launched a microprocessor-based PLC product plc-2, using Intel's 8080 microprocessor. Before that, AMD's 2901 and 2903 bit chip processors were widely used in Modicon and ab PLC.
-In 1977, the German standard din40719-6 was issued.
-In 1978, Mitsubishi Electric Co., Ltd. of Japan launched the PLC product melsec-008.
-In 1979, Motorola released 68000 series 32-bit microprocessor, which was successfully applied in PLC products of Allen Bradley and Siemens.
-In 1979, Modicon released Modbus protocol.
-In 1982, a graphic sequential logic description language grafcet became the French standard nfc03-190. Grafcet is the basis of SFC language in iec61131-3plc programming standard. French Telemecanique PLC supports grafcet programming.
-In 1982, VDI 2880 guidelines were developed in Germany.
-In 1982, iec65b completed the first draft of IEC1131.
-In 1983, Germany formulated DIN 19239 programming standard.
-In 1983, Siemens released SIMATIC S5.
-In 1984, Scott C. ziffer and Joseph J. menter founded ICOM software, which can be used with Allen Bradley PLC to replace T3 terminal. Taylor industrial software, another PLC programming software company, also supports the programming of several PLC products. ICOM and Taylor were the two major independent PLC programming software companies at that time.
-In 1985, Rockwell acquired Allen Bradley.
-In 1985, Mitsubishi of Japan released a series PLC.
-In 1986, Rockwell released PLC-5 based on Motorola 68000 embedded processor.
-In 1988, grafcet became iec848 international standard.
-In 1990, iec1131-1 and iec1131-2 standards were issued.
-In 1992, PLCopen was established to promote IEC1131 standard.
-In March 1993, the first edition of iec1131-3 was published, which integrated other international standards: IEC 50, IEC 559, IEC 617-12, IEC 617-13, IEC 848, ISO / AFNOR, ISO / IEC 646, ISO 8601, ISO 7185, iso7498. Five kinds of standardized PLC programming languages are determined.
(the standard number of IEC1131 was later changed to IEC61131)
-In 1993, Siemens developed PROFIBUS DP fieldbus standard.
-In 1994, Modicon product line released quantum series PLC.
-In 1994, Rockwell acquired ICOM.
-In 1994, Siemens released S7 Series PLC.