The History of PLC Programming
The first PLC’s were built in 1968 by Japan’s TOSHIBA corporation under commission from I.B.M. The PLC was then known as I/O Automation System or popularly known in Japan as the Q-series, mostly because of its letter designation in I.B.M. ‘s product naming convention.
Programming these early PLC’s were only made available through systems manufactured by third parties or via assembler code programming on custom made PLC’s.
In 1972, I.B.M. released its first ever PLC, called the 1800 series PLC, which was programmed using ladder logic, a graphical language of interconnected rungs or contacts and coils or ladders that visually represented relay logic systems. Ladder logic uses single-line symbols to represent the various components in a PLC system.
In 1980, I.B.M. released its second generation PLC, called the 4-series or more famously known as the Series/1 PLC which was built with both 24 bit and 32 bit processors with 5 to 15 input/output units with programmable functions for control applications and supporting a large range of third party products and programming tools.
Programming of these PLC’s were made available through assembler code programming, making the 4-series PLC the first ever to be programmed using assembly language. At this point of time, I.B.M was challenged by number of companies such as Rockwell Automation, Allen-Bradley, Mitsubishi Electric Corporation with their MELSEC PLC series and General electric.
Approximately three years later, in 1983 I.B.M made its first attempt to branch away from being the only one offering programming languages for their PLCs by making available their first third-party programming tool called the I.B.M PLC Editor/2, which was a dedicated programming language for their 4-series PLCs only. But due to lack of market demands and competition from third party manufacturers offering much cheaper alternatives, this dedicated programming software was not able to sustain the prices that I.B.M had placed on it and was soon discontinued.
In 1984 I.B.M made its second attempt to offer programming for their PLCs, by further developing assembly code programming language and also made available a new dedicated programming software called the Micro Logic Control Development System. But due to the same reason of it being too costly and not able to compete with other cheaper alternatives, sales were poor and I.B.M eventually abandoned this tool in favor for third-party programming tools developed by various companies such as Faun Elektrik, PASCO Scientific & Mechatronic Systems, Rockwell Software & Automation Solutions and many others offering much cheaper alternatives with no strings attached unlike the dedicated development software from I.B.M.
In 1985 I.B.M released its third generation PLC, called the 6-series PLC which is compatible with Series 1 & 4 PLC’s programming language and also offered an offline version of it called Programmable Logic Controller Studio/1 for easy portability to multiple platforms or even on-site user sessions. Programming of these PLC’s were made available through third party programming tools such as the I.B.M. Micro Logic Development System (PLD), which was also offered in an online version called the I.B.M PLD/1 and later improved upon to support multiple languages including function block, sequential function chart, ladder logic & structured text and many others.
In 1989 I.B.M offered its fourth generation PLC, called the 7-series or more famously known as the S/7 which is compatible with Series 1 & 4 PLC’s programming language and also offered an offline version of it called Programmable Logic Controller Studio/1 for easy portability to multiple platforms or even on-site user sessions. Programming of these PLC’s were made available through third party programming tools such as I.B.M Micro Logic Development System (PLD), which was also offered in online versions called the I.B.M PLD/1 and later improved upon to support multiple languages including function block, sequential function chart, ladder logic & structured text and many others.
While this only covers a short summary of the history of PLC Programming, there is a lot more to learn and understand about the history and future of PLCs. If you’re looking for a PLC Programming company, contact RL Consulting Inc. today!
