PCs versus PLCs for process control

Soapbox: Don’t settle for faults inherent in PLCs and PCs. Take the best of each for a more effective hybrid system for process control, according to a software and hardware provider to the process industries.

12/19/2011


PLCs have been an old-time favorite for automation and control. The top-down programs and input-output type of ladder logic offered reliable control of process. However, with the ever-growing need for production information and quality control, the inadequacies of the PLCs were exposed.

Turbomation engineers software and hardware integrated systems; hybrid PC and PLC control systems are more popular than ever, the company says. Courtesy: Turbomation

Enter the PC as a tool for automation and control. The PC, with its user friendly operating systems, looked more like a candidate to displace the PLCs. However, the reliability of the operating systems left a lot to be desired. If working on a word processing document and the PC freezes, it is simple to hit the reset button. This, however, is not an acceptable solution when a PC-controlled machine is reaching dangerous operating conditions. Hence the PC is not an answer for process control.

The PLC is inadequate when complex mathematics is required. PLCs do not handle image analysis well either. Even process control like temperature and pressure are not well handled by PLCs where high levels of accuracy are needed. This kind of temperature and pressure control is better left to intelligent field devices like dedicated temperature or pressure controllers. Recently PLCs have been benefitting from special process control modules that may be added to PLCs. One thing that PLCs do very well is discrete control like opening and closing valves. PLCs have been fairly efficient in positioning for robotics.

In short, the question is how to integrate the reliability of the PLC’s discrete control, the precise control of intelligent field devices, and the processing power of the PC. The obvious answer is a hybrid system with the PC as the supervisory device with delegated controls to the PLC and other field devices.

All calibration, data analysis, and data history are handled by the PC. The human machine interface is provided by the PC. Actual process control is carried out by the PLC and the field devices best suited for the application. With the advent of interdevice communication capabilities, hybrid control systems are more popular than ever.

This way the best capabilities of all the devices are safely leveraged for the best results. This model also lends itself to cloud-based remote control or data acquisition.

- Jacob George is application engineering manager at Turbomation, a company engaged in engineering and automation consultation for process control. Edited by Mark T. Hoske, CFE Media, Control Engineering, www.controleng.com.

www.turbomation.com 

http://controleng.com/process 



Engineers' Choice Awards
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by Control Engineering subscribers.
System Integrator Giants
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
System Integrator of the Year
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
How to Maximize Factory Automation Efficiency with Low Cost Machine Vision
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Wireless Reliability in Harsh Environments
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
Human Factors and the Impact on Plant Safety
This eGuide contains a series of articles and videos that considers theoretical and practical; immediate needs and a look into the future.
June 2018
Discrete and process sensor fundamentals, autotuning controls, system integrator roundtable
May 2018
Salary and Career Survey, IT and OT convergence, robotic standards and safety, secure circuit protection
April 2018
Cybersecurity best practices, artificial intelligence, robotic additive manufacturing, embedded systems, IIoT integration, energy efficiency
Edge Computing
This article collection contains several articles on how today's technologies heap benefits onto an edge-computing architecture such as faster computing, better networking, more memory, smarter analytics, cloud-based intelligence, and lower costs.
IIoT: Machines, Equipment, & Asset Management
Articles in this digital report highlight technologies that enable Industrial Internet of Things, IIoT-related products and strategies.
PLCs
Programmable logic controllers (PLCs) represent the logic (decision) part of the control loop of sense, decide, and actuate. Featured articles in this digital report compare PLCs and programmable automation controllers (PACs), industrial PCs, and robotic controllers.
SIDB

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

June 2018
Machine learning, produced water benefits, progressive cavity pumps
April 2018
ROVs, rigs, and the real time; wellsite valve manifolds; AI on a chip; analytics use for pipelines
February 2018
Focus on power systems, process safety, electrical and power systems, edge computing in the oil & gas industry
John O. Ayuk, PE, CFSE, PMP, CAP
Automation Engineer; Wood Group
Doug Baker
System Integrator; Cross Integrated Systems Group
Jose S. Vasquez, Jr.
Jose S. Vasquez, Jr.
Fire & Life Safety Engineer; Technip USA Inc.
Data Centers: Impacts of Climate and Cooling Technology
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
Safety First: Arc Flash 101
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
Critical Power: Hospital Electrical Systems
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
Engineers' Choice Awards
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by Control Engineering subscribers.
System Integrator Giants
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
System Integrator of the Year
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
How to Maximize Factory Automation Efficiency with Low Cost Machine Vision
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Wireless Reliability in Harsh Environments
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
Human Factors and the Impact on Plant Safety
This eGuide contains a series of articles and videos that considers theoretical and practical; immediate needs and a look into the future.
June 2018
Discrete and process sensor fundamentals, autotuning controls, system integrator roundtable
May 2018
Salary and Career Survey, IT and OT convergence, robotic standards and safety, secure circuit protection
April 2018
Cybersecurity best practices, artificial intelligence, robotic additive manufacturing, embedded systems, IIoT integration, energy efficiency
Edge Computing
This article collection contains several articles on how today's technologies heap benefits onto an edge-computing architecture such as faster computing, better networking, more memory, smarter analytics, cloud-based intelligence, and lower costs.
IIoT: Machines, Equipment, & Asset Management
Articles in this digital report highlight technologies that enable Industrial Internet of Things, IIoT-related products and strategies.
PLCs
Programmable logic controllers (PLCs) represent the logic (decision) part of the control loop of sense, decide, and actuate. Featured articles in this digital report compare PLCs and programmable automation controllers (PACs), industrial PCs, and robotic controllers.
SIDB

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

June 2018
Machine learning, produced water benefits, progressive cavity pumps
April 2018
ROVs, rigs, and the real time; wellsite valve manifolds; AI on a chip; analytics use for pipelines
February 2018
Focus on power systems, process safety, electrical and power systems, edge computing in the oil & gas industry
John O. Ayuk, PE, CFSE, PMP, CAP
Automation Engineer; Wood Group
Doug Baker
System Integrator; Cross Integrated Systems Group
Jose S. Vasquez, Jr.
Jose S. Vasquez, Jr.
Fire & Life Safety Engineer; Technip USA Inc.
Data Centers: Impacts of Climate and Cooling Technology
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
Safety First: Arc Flash 101
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
Critical Power: Hospital Electrical Systems
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
Engineers' Choice Awards
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by Control Engineering subscribers.
System Integrator Giants
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
System Integrator of the Year
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
How to Maximize Factory Automation Efficiency with Low Cost Machine Vision
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Wireless Reliability in Harsh Environments
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
Human Factors and the Impact on Plant Safety
This eGuide contains a series of articles and videos that considers theoretical and practical; immediate needs and a look into the future.
June 2018
Discrete and process sensor fundamentals, autotuning controls, system integrator roundtable
May 2018
Salary and Career Survey, IT and OT convergence, robotic standards and safety, secure circuit protection
April 2018
Cybersecurity best practices, artificial intelligence, robotic additive manufacturing, embedded systems, IIoT integration, energy efficiency
Edge Computing
This article collection contains several articles on how today's technologies heap benefits onto an edge-computing architecture such as faster computing, better networking, more memory, smarter analytics, cloud-based intelligence, and lower costs.
IIoT: Machines, Equipment, & Asset Management
Articles in this digital report highlight technologies that enable Industrial Internet of Things, IIoT-related products and strategies.
PLCs
Programmable logic controllers (PLCs) represent the logic (decision) part of the control loop of sense, decide, and actuate. Featured articles in this digital report compare PLCs and programmable automation controllers (PACs), industrial PCs, and robotic controllers.
SIDB

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

June 2018
Machine learning, produced water benefits, progressive cavity pumps
April 2018
ROVs, rigs, and the real time; wellsite valve manifolds; AI on a chip; analytics use for pipelines
February 2018
Focus on power systems, process safety, electrical and power systems, edge computing in the oil & gas industry
John O. Ayuk, PE, CFSE, PMP, CAP
Automation Engineer; Wood Group
Doug Baker
System Integrator; Cross Integrated Systems Group
Jose S. Vasquez, Jr.
Jose S. Vasquez, Jr.
Fire & Life Safety Engineer; Technip USA Inc.
Data Centers: Impacts of Climate and Cooling Technology
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
Safety First: Arc Flash 101
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
Critical Power: Hospital Electrical Systems
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
click me