PLC & PC Programming
|PLC and PC Programming|
|PLC and PC Programming|
One of the most crucial decisions in the initial design phase of a machine is the selection of the control system. Since programmable logic controllers (PLCs) were first introduced in the 1970s, they have dominated the process and automation markets. For years, PLC controllers have led the way for advances in machine automation control. From small controls used in the automotive industry to large-scale controllers running entire factories, the PLC was the primary controller of choice.
However, starting from the early 1990s, the PC has been successfully working its way into those markets as processor speed and range increases, and the cost of those components decreases. The number of applications using a PC has been on the rise, causing an accelerated development that blurs the line between the two technologies. Fifteen years ago, deciding what type of controller to use might have been a clear choice; today, that is no longer the case.
The PLC was developed as a streamlined, flexible, and reliable alternative to switch boxes and relay panels. It was dedicated to specific tasks in the factory, and its language and structure were modeled around the switches and relay panel circuits it was replacing. Furthermore, it had to maintain its robustness and consistent performance in challenging environments that contained relatively high levels of electromagnetic interference (EMI), contamination, and vibration. As time passed, PLC controllers evolved to include the capabilities of motion control, advanced proportional-integral-derivative PID process control, and integrated safety, while also adopting some PC features, such as a web server and networking utilities.
The PC, on the other hand, served a higher level role in the scope of the machine. It was used primarily for complex calculations, monitoring, measuring, and factory networking as well as a user-interface to the PLC. It was usually housed in a more environmentally controlled location because it couldn’t operate as reliably as a PLC in harsh factory conditions.
The PC evolved to include PLC programming, while still containing its core capabilities. The PC has also become a more robust controller, allowing it to operate in the harsh environments where PLCs were more commonly found. Further blending of the technologies is evident in an analysis of their control architectures. With the addition of a PCI card, hardware drivers, and software, a PC can serve as a PLC. The addition of a real-time kernel can enable the PC to support more critical tasking and control algorithms. Then, there are PLCs with a built-in PC that only require a keyboard and mouse to get started.
So, how do you choose between PLC or PC-based architecture? You contact Bevco Engineering so that we can assist you with the specification, design, build, and implementation of what your operation needs.
It is important to analyze and compare differentiating characteristics. There are seven major areas to consider:
- Hardware Integration
View this pdf for more information on the 7 Differentiating Characteristics of PLC / PC
After analyzing the technical requirements and comparing the design options for your machine, Cost needs to be considered. Many applications can be solved by either a PC-based or PLC-based solution, but for some applications, the cost of those solutions can differ widely. A comparison of the potential cost of PC- and PLC-based architectures focuses on four areas: performance, expandability, environment, and programming development effort.
With extensive expertise and intimate knowledge of the system, there might be little or no cost difference between a PC- or PLC-based solution.
We have experience in a variety of PLC controllers. These include but are not limited to:
- Allen-Bradley PLC
- PLC5 Family
- SLC500 Family
- Schneider Electric
- Modicon (M340)
We have also programmed many successful projects using PC-based control systems. These include:
- Honeywell SDS
- National Instruments - LabView
- OPTO22 - ioControl
When you need PLC/PC integration work, turn to Bevco Engineering. Please CONTACT US!