PC based industrial control to replace PLC 3

[henderd]

Our company is looking of a package which can replace current PLC distrubuted IO control system. We currently have issues with the programming difficulties/limitations. We are looking for a PC based system with higher level programming software, and a more mature level of support/library of programs. Any input is appreciated. Also an idea of product learning curve would also be helpful.
Thanks
Dave

 

[nbucska]

It would help to know what do you plan to use it for ?
The more data, the merrier..

I have used PC for different automatization and simulation projects but no canned software.

Tryed to use LABWIEV but I have found it too slow by magnitudes of order...

By the way, you can buy <<$150 PC compatible 2&quot;x3&quot;
computer programmable in any BASIC,FORTRAN,C,C++,PASCAL
etc.




<nbucska@pcperipherals.com>

 

[nbucska]

About learning: do you know -- or have someone who knows--
any PC supported language -- GW-TURBO-QUICK-POWER-BASIC
C,C++,FORTRAN,PASCAL, etc ?


<nbucska@pcperipherals.com>

 

[JesperMP]

What PLC system do you have now ?
What is the application ?
How many i/o ?
Any &quot;special&quot; functions ?

This question cannot be answered easily.
If your PLC is very old and doesnt support &quot;advanced&quot; functions, maybe an option for you could be to upgrade to a more uptodate PLC.

 

[nbucska]

The PLC is an antiquated system, emulating the relay-logic.
Can you imagine solving trigonometric or logarithmic equation in PLC?


<nbucska@pcperipherals.com>

 

[Kiljoy]

CTC-parker's HMI is also a fully functional industrial computer with soft PLC capabilities. You can program in Ladder, statement list, SFC, and I think another one too. You can mix and match them since the programming is modular. By attaching PC104 boards or using the on-board Ethernet port, you can use almost any distributed I/O. They also talk to damned near every PLC too. We toyed with the idea of using them to replace our PLC's (we currently use them as a strict HMI), but as an OEM, it was not cost effective for us.
Go to

http://www.ctcusa.com

The software is completely free.

P.S. Allen-Bradley's RSlogix 500 software (for PLCs) has had logarithmic and trigonometric functions for about the last 10 years.

 

[henderd]

We are developing a SCADA system for remote power systems. We need high speed I/O better than 60 hertz. total inputs are around 20 descrete and 10 analog, outputs are around the same in number. We would also like to beable to monitor and update the system over the internet.
Has anybody have experience with the NI Lookout. Dose it have a similar interface as LabView? thanks,
Dave

 

[JesperMP]

Your application appears to suit a typical setup:
Several local PLCs connected together and to a SCADA system over a network.

What do you mean with &quot;remote power systems&quot; ?
If that is within a location, then I would consider Profibus as it has a reach of 800 m @ 187.5 kbps, or 200 m @ 1.5 Mbps. This can be expanded max 8 times with the use of repeaters. All at a reasonable cost.
If it is in the country side, then the task is more difficult, especially if you need &quot;hispeed&quot; performance.

Todays PLCs have all the &quot;advanced&quot; functionality that you could wish for. Combine it with its reliability and relatively low price, it is the 1st choice for any industrial application.
In other words: The reasons must be VERY good if you want to choose a PC based solution over a PLC based.

Most SCADAs today support Internert functionality.

 

[tomatge]

My thoughts on some comments above ...

In terms of &quot;advanced functions&quot; some PLC equipment is better than others. nbucska's question about trigonometric equations may not be possible or easy on basic PLC equipment, but relatively simple on more top-end gear. For example, with GE-FANUC equipment functions can be programmed from scratch in &quot;C&quot; code, allowing virtually unlimited mathematical processing.

I don't understand henderd's point about SCADA, and how this is related. 20 digital and 10 analogue capability is very small for a SCADA site, which makes me wonder why such a high scanning rate is required. Unless it's for accurate time stamping, in which case a small RTU would probably be cheaper and easier than either a PLC or PC based solution. If it's for power quality or transient type measurements, this is starting to get out of the realm of SCADA/PLC and dedicated equipment for that purpose may be appropriate.

 

[jacekd]

Dear nbucska,
&quot;The PLC is an antiquated system,...&quot; - saying such a thing you reveal that your knowledge of PLCs is antiquated.

Regards,

Jacek

Do it right or don't do it at all.

 

[JonGw]

What you want certainly exists. Despite the catcalls from some naysayers, there are certain things that PCs running software can do better than PLCs for the simple reason that, compared to PLCs, ordinary PCs are faster and more powerful.

The right tool for the job, that's what I say.

If you'd like to discuss the matter further, just ask.

 

[skills]

I've been using Lookout ver. 5.1 a lot lately. No, it doesn't 'feel' much like Labview; but, of course it it targeted to a different end use. Lookout is now a client/ server system and is event driven. Lookout would work well in your application; however, you would still need I/O and probably would need NI's I/O. You can make Lookout an HMI web-server fairly easily, I believe. There are 4 families of NI stuff so be prepared to do some homework! You can get Lookout as a toolkit to Labview 6I if you choose the &quot;supervisory and control module&quot; and then you have the best of both worlds. I would probably opt to do this for some esoteric reasons in this application.

 

[sdb830]

This is a PLC forum group, to state PLC's are antiquated is a ridiculous statement. PLC's are current and have a market that will be around for a long time. Full PC automation control will need to be as reliable and durable as PLC's before they replace them I don’t see that happening for quite some time.
As for the original post;
Most SCADA applications will allow you to schedule communications, Citect for example has a very good modem IO scheduling setup. If the HMI you are looking at doesn’t provide this functionality you can purchase a separate IO server like KEP Server.

 

[mindspan]

Look at

http://www.beckhoff.com

for PC package that is pure 1131 (IEC 61131-3 to be exact), they have all the hardware as well. You can do all your motion (even CNC) here as well.

You are on your own for a HMI though. I will say that getting the two linked up can be very easy if you approach things intelligently.

The control software, TwinCAT, rules. Learning curve? Depends on you, what do you know about 1131? If nothing, well get on it, that IS the way things are heading. You can not go wrong learning more about it.

Robert Trask, PE
Los Angeles, CA USA
bob@remove.mindspan.us

 

[killemall]

If you want robust control, use a robust industrial system, not a PC. What happens when your PC locks up, or crashes?? How can you possibly rely on a PC.

A PC is OK for SCADA, as it is only supervisory, does no actual control. So when it locks up (which happens regularly) the PLC continues to control at full speed.

Labview and NI lookout are toys in my opinion, but serve some pupose in the market (like in the lab).


PLCs can be extremely powerful mathematical machines (Not antiquated). Look at allen bradleys Compact Logix or Control Logix range for example.
Program timed or event driven interupts where you need extremely high speed. IO can be as fast as 1ms. Scan times in the order of 10 to 20ms.



If you really want to use a PC based system, look at allen bradleys soft logix. Use Flex IO on ethernet for the IO. Extremely flexible powerful system.

Then pick from any SCADA package you want to interface with it.

 

[JonGw]

PCs are pretty robust. Granted, I probably would prefer to see a PLC used in critical situations but there are a lot of non-critical situations where a standard PC running something like Wonderware's InControl could not only do anything a PLC would do but a lot more besides.

I regularly set up PCs that run continuously for months/years. It is also getting much easier to set up redundant systems where even in the unlikely event that one machine fails, the backup can assume control seamlessly until the primary is back online.

Like I said before... the right tool for the job.

 

[skills]

Based on what I've seen AB's Soft Logix looks like a toy compared to the mature products that it will contend with. If you're going to go pc-based in control you would do well with those who actually have some experience with this rather than some eleventh hour glue-together by AB.

 

[tnvol]

TR Automation may have the solution you are looking for. Systems can do the control or communicate to PLC's via ehternet or wireless. Systems do not lock-up like Windows based equipment. Good for process, batch, robotic systems, etc. Can develop special libraries also.

Drop me a note at tnvol@mcsa.ws for contacts.





e-commerce
b2b
ymi.us

 

[opencontrolsguy]

Hi henderd

If you're looking at a PC based solution you may want to look into MDSI at

http://www.mdsi2.com

for their line of open control solutions, which incorporate a soft PLC as part of the package.

Their solution to Windows crashing (mentioned in other posts) is to run their OpenCNC software in a real time kernel in reserved memory which allows the control to keep running even if the Windows does crash.

Their latest offerings include complete hardware software solutions in a &quot;no moving parts&quot; form factor which provides the high reliability that the industrial environments have been looking for. This was accomplished by using processors up to 667MHz which can operate fanless, and Compact Flash with Windows Embedded XP eliminates the need for HDD's.

Good luck!

 

[OldPfart]

I normally use Omron CS1 or CJ1 PLCs. These are awesome beasts with all the functionality you could ask for including autotune 2 degree of freedom PID. Some 400 odd functions, including many high level maths functions. I normally use them with Omron Controller Link as the network.
My favoured SCADA system mis definately Citect (

http://www.citect.com).

On a system where there are 9 PLCs and a 3500 tag Citect data base, Citect is reporting 15,500 digital reads per second and 300 word reads.
Very fast and reliable.
Would not suggest the soft PLC option. Too unreliable. Soft PLC runs separately from Windows but if Mr Gates decides to lock up, the computer requires re-booting. Goodbye soft PLC.
The best solution for a computer based system I have seen is an Omron PLC on a PCI crad running remote I/O/ The card requires a separate 24VDC power supply. Mr Gates locks up, computer requires re-booting, PLC on a card continues to run thanks to the separate 24VDC power supply.