Programming languages are of two main categories:
- ST - Structured Text - a very effective higher programming language based on Ada, Pascal, and C. It contains all relevant attributes of modern programming language, inclusive branching (IF-THEN-ELSE and CASE OF), and iteration loop (FOR, WHILE and REPEAT). These elements may be embedded.
- FBD - Function Block Diagram -also known as FUPLA. FUPLA is very close to industrial process control. If describes the behaviour of elements, function blocks, and programs as a set of interconnected graphical blocks, similar to a electronic circuitry. It is a certain system of elements for signal processing.
The choice of the programming language depends on how the programmer is experienced, on the type of the task to be solved, on how deeply the problem is described, and on other circumstances, such as type of industry, best practice of the engineering company, know-how level of the engineers, etc.
As an example, see a logical function which ORs the variables A and B. The result is in variable C.
Structured text language (ST):
C := A or B;
FUPLA, function block language (FBD):