PLC Programming

A PLC (Programmable Logic Controller) is a device that uses digital logic to control various input and output (I/O) processes, even though these inputs and outputs may not be digital in nature, such as a varying analogue electrical signal.

A PLC is essentially a computer which, in order for the PLC to function as desired, must be programmed with some sort of software code. The code is just a defined set of instructions that the PLC understands and executes as required. There are various ways to program a PLC as outlined in IEC 61131-3, these include

  • Ladder Diagram (LD)
  • Functional Block Diagram (FBD)
  • Structured Text (ST)
  • Instruction List (IL)
  • Sequential Function Chart (SFC)

The software code is typically written on an external device, such as a PC or laptop, and then transferred to the PLC via a communication link (cable, network etc.). In order for the PLC to receive the correct set of instructions, the programmer must have an understanding of both the process under control and the coding procedure.

In order for PLC’s to function efficiently and safely they must be programmed correctly. Any error or ‘bug’ in the code may cause the PLC, along with any device it communicates with, to malfunction. With small processes the PLC may cause an inconvenience, with a potential safety hazard if moving machinery is involved. If the PLC’s are running in a large complex process environment, such as an oil or gas refinery, this could cause catastrophic damage including loss of life.

Successful PLC programming requires a thorough understanding of the entire design process, from the initial project scope to knowledge of the process under control, the hardware elements, installation procedures and all hazard considerations. To ensure the best PLC performance is achieved, it is imperative that any PLC programming is done by trained, qualified and experienced PLC engineers.

Automation IT are a professional PLC programming company that have integrated partnerships with the world’s best PLC manufacturers, so have the knowledge and background to engineer the best software coding solutions. Automation IT utilize their own in-house professional PLC programming specialists whose training, knowledge and experience covers all industries, no job is too small or too big.

Automation IT is a complete PLC programming service provider, if you would like to find out more about how Automation IT expert PLC programming services can benefit your company then contact This email address is being protected from spambots. You need JavaScript enabled to view it..