Unification of Mechanical and Electrical Components using PLC Programming

09 Aug Unification of Mechanical and Electrical Components using PLC Programming

PLC Programming in Machine Build

What is PLC Programming and why does it matter?

PLC Programming provides brainpower necessary to allow the machine to operate using logic programmed into the PLC. This article is a brief overview of that process

PLC Programming is the digital logic that is running in the background of a machine unseen to the operator. This logic is designed and programmed in a manner that provides the machine with actuation, monitoring and control and overall safety of a certain process or operation that the machine is required to accomplish. Imagine the process of folding up a box from its unfolded state, a human uses their brain and limbs to fold the sides of the box and tape it on the seams to complete the assembly of the box. Using a combination of inputs and outputs combined with PLC logic we can program a controller to tell a machine to move actuators, and use sensors that would fold the edges of a box together to form the basic shape of the box and then add tape to the seams of the box also using some type of actuator. Essentially the code in the PLC is replacing the human brain and allowing a machine to operate within the guidelines that the controls programmer specifies.

What does a PLC Programmer do?

A PLC programmer is responsible for providing a machine’s controller with logic that allows the machine to function in the most efficient manner as possible. The programmer is also responsible for providing code that is easy to understand and modify in the case that a modification has to be made in the future by someone who did not create the original program.

Complementing the PLC program, a programmer’s role is to also integrate components on the machine using the different protocols that the PLC can support. These pieces of hardware/software can range from remote I/O blocks, vision cameras, barcode readers, servo motors, sensors, pneumatic valve banks, HMIs (Human Machine Interface – touchscreen interfaces) to robots and PCs. The main goal is to allow all of the components in a machine to report back to the PLC so that the PLC can use the logic programmed into the unit to complete the desired outcome.

PLC programming vs. computer programming

Plc programming differs from computer programming logic in the sense that most PLC logic is programmed using ladder logic, while computer programming uses text-based programming such as “C, C+ languages.) Below is an image of ladder logic that demonstrates that two commands that need to “Turn On” or be in a binary state of 1 to turn on the output to the far right. These commands can be mapped out in a simple and easy to understand manner such that a technician can understand what needs to happen before another action is made possible.

PLC Programming Commands


Below is an image of structured text in C language. You can see that rather than having graphical instructions with comments to indicate to the operator what is happening in real-time, text guides the program with IF, AND, OR statements to accomplish a similar task.

C Language Coding at Innovative Automation

The PLC logic can be viewed using PC software that allows the controls programmer to view and modify the logic, in most cases in real-time as the machine is operating. This helps the controls programmer understand what is happening when and troubleshoot any issues that may appear after the offline code is written. Learn more about the different uses of code in controls machine design in this great article.

What does a PLC programmer do at Innovative Automation?

A PLC programmer is responsible for the ensuring that a machine’s controller is functioning properly using code developed by the controls department to allow a machine to complete the process it was designed for. Below you can see an image of an OMRON modular PLC and Safety PLC that is using several different communication methods to allow the machine to operate. The PLC below is using an RS-232 interface to communicate to an outside piece of hardware marking a part, DeviceNET to communicate to Inputs and Outputs that are located outside of the main control panel and Ethernet communication to allow the PLC to communicate with barcode readers, servos and the Safety PLC. The PLC programmer uses all of their combined training to allow all of these devices to communicate with the brain of the system, the PLC. Below is an image of the above-described layout:

PLC Programming in Machine Build

What types of projects does a PLC programmer get to work on?

A PLC programmer can work on jobs that include anything from basic sensors to complex robots. Although a programmer may not do all of the programming required in the outside peripheral devices, they are responsible for making sure all of those components communicate properly with the PLC in a manner that controls them based on the requirements of the process. This usually includes job specific training and previous experience combined to allow the programmer to complete the task at hand. A programmer should expect to work on jobs that include different PLCs and software from different manufacturers. A project that a PLC programmer could work on and include, but not limited to, presses, hydraulic and pneumatic, assembly stations, robotic welding/assembly, vision inspection, and machining applications.

What jobs are available for a control system programmer?

Jobs that are available to a control systems programmer include offline PLC and HMI (Human Machine Interface) programming, robotic programming, servo programming, SCADA (Supervisory control and data acquisition) system programming and machine development. A controls programmer could be working in the local shop programming machines and getting them ready for run-off and install to troubleshooting existing jobs on site. Some programmers are versed in writing code from the ground up and organizing large scale projects and some programmers do service call work to retrofit existing systems currently running in a customer’s plant. The best control systems programmers are those who are experienced in multiple software platforms and communication protocols combined with a good knowledge of hardware application and usage. To find more about what current job opportunities are available check out our careers page.