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There are several ways to program a PLC or PLC each have their advantages and disadvantages, and there is a reason why according to the application to perform we will use one or the other. All these languages belong to the IEC 1131-3 standard. We can distinguish between languages in graphics or textual, the first use an interface and consist of blocks that perform a particular function the seconds are more similar to programming in C or similar.
Graphics languages for automatic
Ladder (LD)
Previous mind to the development of the PLC automations were carried out with electrical relays, which for many designers was much more easy to design electrical schematics that program. This not only language is practical for those who are not experts in programming, is intended for electrical, possesses an advantage to simulate certain systems. Many controllers allow us to see the running program, we can visualize the variables at each time even to force a variable to a value that we want, with a language chart is a lot easier to perform these checks are much more intuitive.
Diagram of blocks of functions (FBD)
In many respects it is similar to the single Ladder to use functions that perform functions in concrete instead of relays (and, or, higher than…), is more similar to a thought this high level but with graphics, programming language for electronic that I used to work with logic gates and integrated circuits. This language is simple and intuitive, very practical for people who don't know too much about languages such as C or Pascal. The advantage continues being similar to the previous can simulate the program on the Automat (or emulate it in PC) and force variable or simply view them to detect possible errors. Say that in environments industrial can have engines or systems that generate fields electromagnetic that can alter some signals by this is important know that would happen if a variable acquires a particular value in a moment.
Textual language for automata
Language structured text (SD)
This language is similar to the typical computer as C, PASCAL or BASIC, us allows have a control greater that those graphics vistosanteriormente. It is a high-level language and therefore you must compile to something you understand the machine. This language is the best for create functions complex, the computer that not have notions of electricity or electronic tends to be which best handled.
(IL) instruction list
Sometimes you maybe need to set level of hardware, in low level languages, so we have this language, is the language itself Automat machine. Personally I think that it is the least used, perhaps use to create functions or programs faster that generate us compiler or to access certain areas that would be impossible with other resources.
GRAFCET language of automata.
Sequential functions (CFS)
We must remember that a robot is a machine to perform a sequence of instructions that we program, read a few posts and modifies some outputs, is intended for industrial machinery that always carries out functions of this kind. Measure a temperature if it is very hot to activate fan if it is very cold to activate the heater, if there is a signal of emergency stop of the machine to prevent physical damage to operators… What in France designed a structure called GRAFCET, it was a design to program PLC and consists of making a flowchart of sequences that should make the machine, later became a language of its own. Basically, it is to make life easier for programmers of automata can make each sequence in one of the above languages and be easy to bring to reality what we think.
