Systems using PLC controllers. Designing of control algorithms

Industrial PLCs are commonly used to automate industrial processes. The literature devoted to them is extensive, however, these are books describing mainly the functional possibilities of individual driver models, and consistently omitting the design of their control algorithms.

The book fills this gap by describing in an accessible way various practical problems related to the design of control algorithms for complex PLCs for PLCs. All issues discussed are illustrated by appropriate examples.

The design of process control algorithms in automatic and manual mode, algorithms for detecting process equipment failures and control of these devices after failure detection or after using the emergency stop button are described. Using the design method presented in the book, all these algorithms can be developed independently of each other and then integrated into one algorithm. The author presented several ways of this integration.

The design description uses a simplified sequential control language. The algorithms written in it are not only very readable, but can also be immediately run on all PLCs programmable in a standardized SFC language or in such languages as Grafcet or GRAPH5. Since not all PLCs can be programmed in this way, the method of translating the control algorithm graphs into the LD ladder diagram language and IL instruction list language is also described. It can also be used to write programs in other languages used for programming PLCs.

The last chapter discusses the design of numerical calculation algorithms typical of control systems for PLCs. It requires a specific approach due to the PLC-specific limitation of the list of instructions to basic arithmetic operations on integers, and this problem is practically not addressed in the literature on drivers.

The book is intended for a wide range of designers and users of automation systems using PLC drivers, as well as students of most polytechnic faculties. It will be especially useful for automation engineers and technologists of automated processes using PLC or PAC controllers when designing the control system and its subsequent modifications.