PC based industrial control to replace PLC
PC based industrial control to replace PLC
(OP)
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
Thanks
Dave





RE: PC based industrial control to replace PLC
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"x3"
computer programmable in any BASIC,FORTRAN,C,C++,PASCAL
etc.
<nbucska@pcperipherals.com>
RE: PC based industrial control to replace PLC
any PC supported language -- GW-TURBO-QUICK-POWER-BASIC
C,C++,FORTRAN,PASCAL, etc ?
<nbucska@pcperipherals.com>
RE: PC based industrial control to replace PLC
What is the application ?
How many i/o ?
Any "special" functions ?
This question cannot be answered easily.
If your PLC is very old and doesnt support "advanced" functions, maybe an option for you could be to upgrade to a more uptodate PLC.
RE: PC based industrial control to replace PLC
Can you imagine solving trigonometric or logarithmic equation in PLC?
<nbucska@pcperipherals.com>
RE: PC based industrial control to replace PLC
Go to 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.
RE: PC based industrial control to replace PLC
Has anybody have experience with the NI Lookout. Dose it have a similar interface as LabView? thanks,
Dave
RE: PC based industrial control to replace PLC
Several local PLCs connected together and to a SCADA system over a network.
What do you mean with "remote power systems" ?
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 "hispeed" performance.
Todays PLCs have all the "advanced" 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.
RE: PC based industrial control to replace PLC
In terms of "advanced functions" 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 "C" 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.
RE: PC based industrial control to replace PLC
"The PLC is an antiquated system,..." - 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.
RE: PC based industrial control to replace PLC
The right tool for the job, that's what I say.
If you'd like to discuss the matter further, just ask.
RE: PC based industrial control to replace PLC
RE: PC based industrial control to replace PLC
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.
RE: PC based industrial control to replace PLC
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
RE: PC based industrial control to replace PLC
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.
RE: PC based industrial control to replace PLC
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.
RE: PC based industrial control to replace PLC
RE: PC based industrial control to replace PLC
Drop me a note at tnvol@mcsa.ws for contacts.
e-commerce
b2b
ymi.us
RE: PC based industrial control to replace PLC
If you're looking at a PC based solution you may want to look into MDSI at 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 "no moving parts" 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!
RE: PC based industrial control to replace PLC
My favoured SCADA system mis definately Citect (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.
RE: PC based industrial control to replace PLC
"The Push behind PC control".
MACHINE DESIGN MAY 15, 2001 www.machinedesign.com
May not be applicable to today but good comparison I thought.
David Baird
mrbaird@hotmail.com
Sr Controls Engineer
EET degree.
Journeyman Electrician.
RE: PC based industrial control to replace PLC
very nice link......I see a star in your future!!!
Kind regards,
Afterhrs