PLC market growing

[JRW]

Here/s good news

http://www.manufacturing.net/ctl/article/CA6388002.html

 

[inductiveautomation]

Very cool! Any similar studies/articles on HMI/SCADA use? I'm curious if PC based control is growing or is stagnant.

 

[BobB]

I'm curious if PC based control is growing or is stagnant

Hopefully shrinking!

I notice they mention PACs - most modern PLCs can do what these devices can do because of extended/expanded functions etc from what I can see. There has been a move in Ozz for some consultants to try and use SCADA and standard PLCs for BMS systems to get away from the prorietary stuff that has been traditionally used for this. The mechanical people have a tendancy to want to remove warranty unless thier preferred BMS contractor does the work. I have been there trying to fight it on several projects. When warranty removal is brought up, the clients tend to go back to the traditional method.

 

[SAH]

Why do they want to remove the warranty?

 

[inductiveautomation]

BobB,
When I said "PC based controls", I meant to be referencing my earlier sentance, referring to HMI/SCADA - the presentation layer not the brains. I wasn't referring to using PC based PLCs or Programmable Automation Controllers. To be honest, I think that (in theory) better, cheaper, and more reliable PLCs could be implemented by leveraging parts from standard PC computing, but until I see those devices my recommendation will be PLC based control - I assume that's what you mean when you say "traditional method" - that you're not referring to cabinets full of relays.

Would you mind being more specific on the meaning of OZZ, BMS, and the warrenty comment. I didn't follow you on those. What have you been fighting for years?

Hopefully shrinking!

I notice they mention PACs - most modern PLCs can do what these devices can do because of extended/expanded functions etc from what I can see. There has been a move in Ozz for some consultants to try and use SCADA and standard PLCs for BMS systems to get away from the prorietary stuff that has been traditionally used for this. The mechanical people have a tendancy to want to remove warranty unless thier preferred BMS contractor does the work. I have been there trying to fight it on several projects. When warranty removal is brought up, the clients tend to go back to the traditional method.

 

[rsdoran]

Hopefully shrinking!

I notice they mention PACs - most modern PLCs can do what these devices can do because of extended/expanded functions etc from what I can see. There has been a move in Ozz for some consultants to try and use SCADA and standard PLCs for BMS systems to get away from the prorietary stuff that has been traditionally used for this. The mechanical people have a tendancy to want to remove warranty unless thier preferred BMS contractor does the work. I have been there trying to fight it on several projects. When warranty removal is brought up, the clients tend to go back to the traditional method.

Part of this I do not understand, PAC's did not technically come into existence until 2001. The main differences between PAC and PLC is PAC's are suppose to offer a more open architecture that allows less concern for compatibility issues.

I get a little confused on the differences overall. AB's Contrologix is promoted as a PAC system, it offers the capability of programming the controller and other devices in the system with the same software.

I think there are differences when it comes to scan, with a plc it scans continuously but pac's use tags and update as needed.

I thought the objective of PAC's was to give you PC capabilities in a PLC type system.

Why would you move away from something that is new and offers more capabilities? Yes PLC's have expanded capabilities but PAC's are being designed with those capabilities incorporated.

OZZ=Aussie=Australia
Under the context used I think BMS is Building Management Systems, Bob can correct that if necessary.

 

[PhilipW]

The driver for distinguishing between a PLC and a PAC was that the former, the PLC, was a name first used by AB in the early 1970's to describle a controller that really could only solve Boolean logic efficiently and had a very closed and relatively rigid proprietary architecture.

By contrast the ControlLogix system can be efficiently applied to not only machine logic, but the much wider disciplines of motion control and process control at the same time, while allowing a much greater openess and flexibility.

I guess the marketing dept. wanted a new term to illustrate this.

 

[inductiveautomation]

RSdoran and PhilipW,
Thanks for the clarification. I guess I need to talk about specific implementations instead of broad technology classes - especially, as Philip pointed out, when the marketing people get involved. I'm all about newer, better, technologies provided that they actually work. I'm thinking that Bob was referring to standard PCs running emulation software to do a PLCs job. Clearly off the shelf PCs weren't designed for that type of application. The same applies to mechanical hard drives, computer power supplies, and most PC operating systems.

 

[BobB]

OZZ=Aussie=Australia
Under the context used I think BMS is Building Management Systems, Bob can correct that if necessary.

Correct.

I'm thinking that Bob was referring to standard PCs running emulation software to do a PLCs job.

Also correct. I guess I misunderstood what was really meant.

Clearly off the shelf PCs weren't designed for that type of application.

There are quite a few companies out there that would disagree with you. I fully agree and have no intention of getting involved with "soft PLC" projects as I do not agree with the safety/functionality/reliability claims made of them. The only PC based control system that would tempt me is a PLC on a PCI card with it's own power supply and remote I/O. Omron have one and so do many other PLC suppliers. They even have a separate power supply to them (24VDC) and can be removed from the computer still running (bit of cutting required to get the card out).

remove warranty

Means just that. They threatened to remove the warranty on chillers, pumps etc unless their traditional BMS people did not do all the control work.

By contrast the ControlLogix system can be efficiently applied to not only machine logic, but the much wider disciplines of motion control and process control at the same time, while allowing a much greater openess and flexibility.

This is what I was referring to with the expanded functions available in PLCs. They do not have to be marketed as PACS to have the functionality.

Omron have referred to their modern day PLCs as PCs for years now, very confusing of course. So is PAC really. The Omron reference to PC stands for Programmable Controller.

 

[Doug_Adam]

PLCs are dropping in price.
They are becomming more affordable.
People will buy more of them and use them in roles they wouldn't have in the past.
Thus, the market grows.

 

[RussB]

Part of this I do not understand, PAC's did not technically come into existence until 2001. The main differences between PAC and PLC is PAC's are suppose to offer a more open architecture that allows less concern for compatibility issues.

Don't believe everything your read.
The PAC is mostly marketing. As it has been noted, the PLC is dropping in price and elevating in performance. Something need to be done to keep the margin up for the manufacturers to continue making them better, faster, easier, and more "PC-like". Enter the PAC.