The history of the industrial automotive PLC (which stands for programmable logic controller) begins in 1968 in North America. Prior to the advent of the PLC, control, sequencing, and safety interlock logic for manufacturing auto mobiles was accomplished using hundreds or thousands of relays, cam timers, and drum sequencers and dedicated closed-loop controllers. This was not an efficient or practical process and the industrial automation PLC was invented in response to the needs of the American automotive manufacturing industry.
Industrial Automation PLC
The industrial automation PLC can be seen as the next level in technological process for the automation industry. The PLC was created to lessen work and decrease costs. Before the PLC, the process to update and rewire the facilities for use in the up-coming years was time-consuming and very expensive. This was because electricians had to rewire each and every relay individually. The PLC changed that.
Programmable Logic Controllers History
The history of programmable logic controllers is quite interesting and here follows a bit more on the subject. In 1968 GM Hydramatic (the automatic transmission division of General Motors) requested proposals for a new prototype electronic replacement for hard-wired relay systems. Many examples were submitted and eventually the winning proposal belonged to Bedford Associates, a medium sized company based in Bedford, Massachusetts. Thus, the very first PLC, designated the 084 because it was Bedford Associates’ eighty-fourth project, was the result.
- Early PLCs were designed to replace relay logic systems. As was said above, these relay logic systems required time-consuming and costly yearly upgrades, the PLCs were designed to cut costs and labor hours. These PLCs were programmed in “ladder logic”, which strongly resembles a schematic diagram of relay logic. This program notation was chosen to reduce training demands for the existing technicians. Other early PLCs used a form of instruction list programming, based on a stack-based logic solver.
- In reply to the over-whelming success of the first PLC, Bedford Associates established an entirely new company to deal with the development, manufacturing, selling, and servicing this new product. It was called Modicon, which stood for MOdular DIgital CONtroller. The big man and ‘father’ of PLC – Dick Morley – worked on the project. In 1977, the Modicon brand was sold to Gould Electronic. It was to trade hands once more to AEG, before finding its permanent home with Schneider Electric, France.
- The 084 models, however, will always be honored for starting the process that led to modern day programmable logic controller units. One of the very first models built in the 1960s is now on display at Modicon’s headquarters in North Andover, Massachusetts. It was presented to Modicon by GM, when the unit was retired after nearly twenty years of uninterrupted service.
- PLCs were adopted in the automation industry where the more advanced software revision was implemented to replace the re-wiring of hard-wired control panels when production models changed. The yearly process to rewire and program each relay every year was a time consuming and very expensive exercise. The industrial automation PLCwas created in response to that expense. The automotive industry is still one of the largest users of PLCs.
The history of programmable logic controllers (shortened to PLCs across the board) is a fairly short one as the concept of PLCs was only recently invented in reply to a need in the North American automotive manufacturing industry. The automotive industry is still one of the largest users of PLCs. Programmable logic controllers were initially adopted by the automotive industry where software revision replaced the re-wiring of hard-wired control panels when production models changed. The history of programmable logic controllers was informed by the hundreds of thousands of relays, cam timers and drum sequencers and dedicated closed-loop controllers that enabled the control, sequencing, and safety interlock logic for manufacturing auto mobiles prior to its invention.
The huge number of relays etc. that comprised the PLCs predecessor came hand in hand with a very time consuming and costly yearly updating process, as it was necessary for the electricians to rewire each and every relay. The automatic transmission division for General Motors – entitled GM Hydramatic – put the process in motion for the advent of the PLC in 1968 when it issued a request for proposal for an electronic replacement for hard-wired relay systems. Companies from far and wide came forward with ideas, but eventually the winning proposal came from a company from Bedford Massachusetts called Bedford Associates.
The First PLC Prototype
- The very first PLC prototype was numbered 084, as it was only their 84th project. Following from this, Bedford associated started a brand new company dedicated entirely to this new product.
- The company was called Modicon, a name which stood for: MOdular DIgital CONtroller.
- The brand was sold nine years later to Gould Electronics, followed by German Company AEG and then by French Schneider Electric, the current owner.
- One of the very first PLC models ever built it on display at the headquarters of Modicon, which are based in North Andover, Massachusetts.
- It was presented to Modicon by GM, when the unit was retired after nearly twenty years of continued and uninterrupted service.
- Modicon used the number 84 and put it at the end of its product range until the 984 made its appearance.
The early PLCs – that were programmed in PLC ladder logic were designed to replace relay logic systems. The ladder logic looks very much like a schematic diagram of relay logic. This program notation was chosen specifically in order to reduce training demands for the existing technicians – the less to learn the quicker and more efficient the process would become. Today PLC software enables programmers to fully customize the units to control almost any task imaginable.
History of programmable logic controllers then saw the organic process of technological growth leading to the marriage of SCADA and PLC. The term SCADA usually refers to centralized systems which monitor and control entire sites, or complexes of systems spread out over large areas (anything between an industrial plant and a country). Most control actions are performed automatically by Remote Terminal Units (“RTUs”) or by programmable logic controllers (“PLCs”). Host control functions are usually restricted to basic overriding or supervisory level intervention.