Some applications require specific quantities of raw materials be combined in specific ways for particular durations to produce an intermediate or end result. A batch process performs list of actions in a sequence. It executes a series of non-interactive actions all at one time. Once a batch job begins, it continues until it is done. One example is the production of adhesives and glues, which normally require the mixing of raw materials in a heated vessel for a period of time to form a quantity of end product. Other important examples are the production of food, beverages and medicine. Batch processes are generally used to produce a relatively low to intermediate quantity of product per year (a few pounds to millions of pounds).
Figure 5 Process Side Hardware
HMI stands for Human Machine Interface. It is not a full control system, but rather focuses on the supervisory level. As such, it is a purely hardware package that is positioned on top of hardware to which it is interfaced, in general via Programmable Logic Controllers (PLCs), or other commercial hardware modules.
It is a small scale control system for automated industrial processes like municipal water supplies, power generation, steel manufacturing etc.