1660338823553 Asktheexperts

PLC and HMI platforms

Aug. 8, 2005
Process control authority Bela Liptak brings in specialists from his cadre of co-authors to answer a reader's question. Find out which PLCs and HMIs they recommend to a wallboard manufacturer in West Virginia.
QUESTION:I WOULD like to ask for your comments and suggestions. I have your Volumes 1, 2 and 3 , and find these handbooks to be an excellent source of technical information. We are constructing a large wallboard manufacturing plant in West Virginia. We are currently at the crossroads to decide whether we go with Siemens S7 PLC and WinCC HMI platform, or Allen-Bradley ControlLogix PLC and Wonderware InTouch HMI platform for the plant automation and controls. We are currently collecting data and analyzing the pros and cons of both systems. Some of the areas of special concern are: Automation performance comparison; Software friendliness and ease of use; Local plant technical support availability; Availability of personnel resources familiar with either system; Networking superiority; Automation superiority; Price comparison; etc.

Any specific comments/suggestions you may have is highly valued for someone trying to decide between the two systems. Also, if you know of anyone in your network who has gone down this decision path, please forward this inquiry as I would like to ask for their comments/suggestions as well. Thank you for your time.

Sam Roe, Sr. Electrical/Automation Engineer, BPB America


THE ARCHITECTURE of the system is important. This applies to hardware architecture as well as software architecture. The central component of hardware the architecture is the control-network. Without a doubt this shall be based on standard Ethernet. I stress standard Ethernet, not modified "industrial" Ethernet requiring specialized hardware and which does not use IP. For availability it is important that true duplicated "DCS style" redundancy is supported, not just ring topology. The application protocol on top of IP is critical for interoperability between devices from different manufacturers as well as package unit integration. Do not go for proprietary protocols over Ethernet and IP. These criteria pretty much narrows the control-network platform down to Foundation fieldbus HSE.
Siemens does not support HSE, Allen-Bradley does to some extent, but there are other options you should also look at.

At the core of the software architecture you need a technology to exchange data between hardware and software, and between the different software applications. Without a doubt this shall be OPC, including the principal flavors OPC-DA, OPC-A&E, and OPC-HDA. Both Wondwerware and WinCC support at
least OPC-DA. Wondwerware maps it to their own solution loosing some of the easy of use - this could have changed. I have no experience with WinCC. There are other options you should also look at. There are other software technologies you should make sure are supported: SQL/ODBC/OLE_DB/ADO database access, ActiveX graphics components and OLE container, DDE for legacy, VBA for script, and HTML for web viewing etc.

For OPC and other software technologies, take a look at the book "Software for Automation: Architecture, Integration, and Security." ISBN: 1-55617-898-0; Publisher: ISA.

For Ethernet, take a look at the book "Fieldbuses for Process Control: Engineering, Operation, and Maintenance." ISBN 1-55617-760-7; Publisher: ISA

Jonas Berge, SMAR

IS THERE some reason you've limited your evaluation to the two combinations indicated?  A good reason might be that there's already expereience with all of these products elsewhere in your company. 

On the other hand, if there's not a particularly strong reason to impose such a limitation, you might want to include at least a couple other possibilities:  

  • In the PLC area, Modicon (Schneider Automation) especially, and perhaps GE Fanuc.
  • In the HMI area, Intellution Fix (now owned by GE), and RSView32 (Rockwell Automation/Allen-Bradley), and perhaps CiTect.

As for PLC's, I have personal experience with Modicon (584, 984, Quantum) and Allen-Bradley (PLC-5, SLC-500, ControlLogix) in pulp and paper and food industry applications and find both to be solid products, but have slight preference for Modicon.

As for HMI's, I have personal experience with Wonderware and Intellution, more hands-on experience with Wonderware, but, slight preference for Intellution for technical and commercial reasons.

This may not have helped - more opinion based on personal experience. My Modicon preference comes from ealy days employed in the Cellulose and Specialties division of Procter and Gamble, where we chose Modicon over Allen-Bradley as the std. for that division of the co. because it could better meet higher performance reqt's in the pulp and paper mills.

Of course, keep in mind that most leading HMI's will integrate well with most leading PLC's. There may be some minor advantages in pairing ControlLogix-RSView, both Rockwell-AB products.

R. H. (Rick) Meeker, Jr., P.E. , Reliable Power and Controls Corp./Process Control Solutions, Inc., Tallahassee, Fla.

  Need an Expert Opinion?

Send your knotty control and automation questions to Bela Liptak at [email protected]. Liptak will either answer the questions himself or bring in specialists from his cadre of Instrument Engineer’s Handbook, Fourth Edition co-authors. Questions and answers will be published online on www.ControlGlobal.com. Each month, Bela will pick the best question, and publish it, along with the answer in CONTROL. If your question is chosen, a prize will be awarded.

Sponsored Recommendations

Measurement instrumentation for improving hydrogen storage and transport

Hydrogen provides a decarbonization opportunity. Learn more about maximizing the potential of hydrogen.

Get Hands-On Training in Emerson's Interactive Plant Environment

Enhance the training experience and increase retention by training hands-on in Emerson's Interactive Plant Environment. Build skills here so you have them where and when it matters...

Learn About: Micro Motion™ 4700 Config I/O Coriolis Transmitter

An Advanced Transmitter that Expands Connectivity

Learn about: Micro Motion G-Series Coriolis Flow and Density Meters

The Micro Motion G-Series is designed to help you access the benefits of Coriolis technology even when available space is limited.