If the processor freezes or fails the process will not continue to read the
ladder diagram and output action will not change.
The control algorithm was written through
ladder diagram. The controller was tested and verified by using a real-time liquid level tank system.
Programming of the system can be done in high level "C" language or using an PLC graphical user interface (IEC 1131-3) with the following choice of languages: function block diagram;
ladder diagram; instruction list; structured text; and sequential function chart.
* The NAiS Control 1131, another software product from Aromat, supports four programming languages: Instruction List, Function Block Diagram,
Ladder Diagram, and Sequential Function Chart.
Hayakawa uses an abstraction
ladder diagram to illustrate the process of abstracting from the lowest (the associative level), where interactions between the nervous system and something outside them are made.
Acceptance of programmable controllers (PCs) over the past 15 years is directly attributable to their user-friendliness, both in terms of hardware, and the familiar relay
ladder diagram language by which the PC was programmed.
Each Call is also depicted by message sequence, which gives
ladder diagram of the call flow between the Called and the Calling numbers.
It uses various programming languages such as
ladder diagram, functional block diagram, and instruction lists to regulate processes.
As define IEC 61131-3, standard programming languages for PLC are Structured Text (ST),
Ladder Diagram (LD), Instruction List (IL), Sequential Function Chart (SFC) and Function Block Diagram (FBD).