While making a quality asphalt product is still paramount for plant automation, in today's information age, plant automation must play other key roles in the overall enterprise in order for producers to be competitive, especially in an industry that has seen much consolidation in the past decade. Plant automation must support real-time management decisions by providing up-to-the-minute company-wide data, accessible from anywhere in the enterprise. It must allow office and IT personnel to control business data in real-time, while allowing operators to concentrate on running plants. It must mold itself to fit the unique business processes of the producer without requiring the custom programming that has stunted the agility of past systems. Yes, plant automation for the asphalt industry has come a long way to be sure. Here's a brief history.
Prior to 1970
Prior to 1970 asphalt plant automation was entirely electromechanical. This meant the controls for the plant were entirely electric and were based on what is known as relay logic.
Early controls were composed of relay switches, which being mechanical, wore out quickly. These switches were very susceptible to heat, dust, moisture and other natural elements, making them unreliable.
The physical size of early controls was very large as compared to today's controls. They were extremely heavy and not portable. Although these machines were cumbersome by today's standards, they did increase productivity by speeding up the mixing/loading process.
With the advent of transistor and integrated circuit technology, controls became electronic instead of electric in this period.
Physically, integrated circuits were much smaller than relay switches. The integrated circuits were also faster, but the biggest advantage was their reliability. They used no moving parts and were therefore immune to the mechanical (moving) problems encountered with relay switches.
During this time, memory in the controls became economically feasible. Cassette tapes also became a popular choice for memory because of their capability to store information indefinitely. However, the tapes were very susceptible to dust, dirt and moisture.
In 1974, the first microprocessor-based control was installed on an asphalt plant. This year also marked the first time that cassette tapes were bypassed in favor of another type of memory storage: floppy disks. The disks were much faster than tapes but, like tapes, they were susceptible to the environment.
In 1977, a new type of memory was introduced known as EPROM (Erasable Programmable Read Only Memory) and ROM (Read Only Memory). These types of memory were impervious to dust, dirt, heat and even coffee spills. EPROMs were also extremely fast. In this era, control systems also became much smaller and could fit on a tabletop desk. As integrated circuits grew smaller and smaller, this enabled dedicated systems to add more and more capacity without adding to the physical size of the control.
The '80s brought about the personal computer revolution, and in 1984 the first PC was used to control an asphalt plant. Computers were everywhere and the ability to interface the office with the plant was a logical step to eliminate hand-written administrative functions. Prior to building the communication interface between office and plant computers, information generated at the plant had to be re-entered into the office computer. This was often time consuming, expensive, and prone to error.
Background communications to the plants was introduced in 1989. Background means that another task can be occurring and be invisible to the plant operator. More specifically, the plant operator could be running the asphalt plant with all of its requirements and, at the same time, the office could call in and update files, retrieve data, or generate reports. Office tasks became completely invisible to the plant operators and did not interfere with their work.