Control.com - Nerds in Control

We are in the middle of design for one of the most complex fish hatcheries ever to be built in North America. Our engineering consultant is recommending standard PLC and SCADA alarm and control system but one of our staff is really pushing a WinPLC based system. I can find little if any info on the implementation of such a system. Are WinPLC systems commonly used in general industry? Or is this still an emerging field?

I suspect this is what the OP is referring to:

http://www.hosteng.com/HW-Products/WinPLC/WinPLC.htm

The WinPLC is a diskless runtime control platform that gives you all of the best features of both traditional PLCs and Windows capable PCs. The WinPLC allows us to take full advantage of all the recent advances in software technologies while still maintaining the ruggedness of the PLC type hardware. The WinPLC was the first platform to provide an industry standard operating system in a PLC form factor.

Really? Not. Deception and marketing hype.

Here's a reality check. Our firm remotely administers numerous Win CE devices via VPN and the internet. We have had to install IP addressable relays (brand name webrelay) in the power circuits of these devices in order to power cycle them because the O/S locks up so often. Record this URL,
http://www.micro-decisions.com/rio/webrelay.htm
if your associate is devious enough to win the argument. You'll be able to restart the PLC remotely from your desktop whenever it locks up. Hopefully the fish pond won't drain each time it happens.

Win CE might be fine for playthings in an economy of superfluous wealth. But serious control? Never. Run from Win CE. It is a very, very bad practical joke. It's the kind of thing one wishes on his enemy.

It doesn't matter what the form factor of a controller is. Serial murderers are packaged with charming, engaging personalities. But they are still serial murderers. A box that looks like a PLC but runs any version of Windows is NOT a PLC, never will be, and is a disaster in the waiting. It is waiting to murder your process.

I'm not sure what a fish hatchery controls, but I can well imagine sluice gates, drains, feed water, liquid feeding systems, level controllers and what not routinely going into fail safe mode when the CE box locks up.

Your engineering consultant is on track and is worth what you're paying him for. Your associate is a fool to recommend control through CE.

Any brand name PLC is built to be robust. Win CE isn't. It's fine to put your SCADA on Windows, it isn't controlling the process. Leave process control to REAL controllers, not to a PLC wannabee like CE.

David

It's not very fast either - only 40 or 100 millihertz! (But it does have 4 megabytes of memory).

In reply to Bruce Durdle: I believe you meant 40 to 100 millisecond scan. 40 to 100 "millihertz" would be 25 to 10 seconds scan (hertz is scans/second, so 1 millihertz would be 1000 seconds). I'm sure it's not that slow.

As for amount of memory, that is a poor guide to how much it can do. We don't know how much memory it needs to do anything, and that is something that varies drastically between different PLC designs.

I was referring to the specifications on
http://www.hosteng.com/HW-Products/WinPLC/WinPLC.htm. Processor speed was given as 40 mHz, 100 mHz, 100 mHz while the memory capacity was 4 MB/2 Mb/16 Kb.

Just another instance of marketers not really knowing or appreciating the significance of unit prefixes!

In reply to Bruce Durdle: Sorry. I guess I didn't get the joke at first. I was looking at the Automation Direct specs, and they had the correct units (MHz rather than mHz), so I didn't notice this problem.

I do notice though that neither site (Automation Direct nor Host Engineering) have any real specs as to how fast the WinPLC with the Think & Do software actually is. Both sites tell us that the microprocessor runs at 40 or 100 MHz. However, since we don't know how fast the software runs we really have no idea how fast or slow the system actually is in terms of scans per second, boolean operations per second, or any other benchmark that is actually useful. The Flash/RAM size also doesn't tell us much either, since it tells us nothing about how large of a program we can actually load.

Another point that I noticed when reading the fine print is that only certain I/O modules are supported by the WinPLC. There also seems to be a problem with some revision levels of WinPLC not supporting some revision levels of I/O modules that are in the supported list. In other words, know your application needs in detail and read the fine print before using this product.

According to Host Engineering, you can buy a "bare" WinPLC without the Think & Do software. In this case you can buy a development kit to write your own software in C/C++. I can't imagine wanting to do this myself, but this question has come up occasionally.

Hi Michael I seriously considered porting a Linux PLC to the WinPLC. Seem quite doable since there is a Linux port for the H processor they use.  The Host folks, while friendly enough, had absolutely no interest in the project and the cost to do it on my own is prohibitive.

That is to say, there are cheaper alternatives for a sole proprietor or at least the cost is spread out to fit my toybox budget.  If someone has one they aren't using and would like to lend it or donate it, I am still interested because I still don't have a PLC hardware platform that runs Linux.  The Host folks might even come around if they saw something running.  The port would, of course, be  GPL.  I don't have the time anymore for a whole PLC system, but perhaps a stone for the soup?

Regards
cww

I also looked at this a few years ago. In the end it look to me like a good entertainment option, but the platform without software loaded was too expensive to compete with commodity hardware.

The only reason for it to work would be to go head to head against commodity hardware, and in the commodities market price is all that matters.

If you were looking to build a "new" PLC platform this isn't the place to start.

MB
--
Michael Batchelor
www.IndustrialInformatics.com

Yeah, it's kinda strange considering how they price the rest of their gear. Any high volume SOC is going to beat any low volume SBC, but a lot of people seem to want to prove they can build a PC. At this point, there really isn't much point in building the core, but the "add a bus" thing for low cost IO is still attractive. It's a shame there seems to be a fairly large minimum cost for the hardware to run a TCP/IP or UDP stack to take advantage of cheap ethernet. I could live with no backplane IO if Ethernet IO wasn't so spendy. Of course, if space is not an issue you can use an old PC. :^)

Regards

cww

PC 104 has always intrigued me, as well. I spend a fair amount of time discussing a project with a guy to port a proprietary TCP/IP stack to for him. He was interested in manufacturing some kind of system that never came to market.

I don't know, but it seems to me that this, or at least something like it, is probably the basis of the fanless systems on the market now.

MB
--
Michael Batchelor
www.IndustrialInformatics.com

Industrial Informatics, Inc.
3281 Associate Dr.
N. Charleston, SC 29418

843-329-0342 x111 Voice
843-412-2692 Cell
843-329-0343 FAX

In reply to Michael Batchelor: Most PC/104 vendors offer a free Linux port for their boards. That is the most practical way to get a TCP/IP stack for them.

PC/104 boards are usually very limited in terms of RAM or flash. This means the Linux build is an "embedded" type rather than a desktop build. That usually means things like Busybox instead of BASH, no graphics, etc. If you are developing software for them, you are doing embedded style programming.

If you are looking for fanless PC systems, look at things like mini-ITX (and nano, pico, etc.). Mini-ITX is 17 cm x 17 cm. Several vendors sell in this board format, with VIA being the biggest. A number of vendors are also selling similar systems in various proprietary small form factor board formats. They have fanless versions (as well as faster versions with fans), and various options for booting from flash. They are usually full featured 32 bit PCs, although with slower CPUs (to cut size and heat output).

The fanless systems you see on the market for things like entertainment systems, kiosks, POS, etc. are usually these small form factor PCs. Motherboard prices start at about $150 (including CPU, but excluding RAM).

If you have a method to flash a new bootloader
and a candidate boot loader to install, then I
have a WinPLC that I can loan. I'll even help
you with the project. Your first, and perhaps
most difficult step will be to install a boot
loader that can find the kernel, load to RAM,
and start execution, all preferably logged to
the RS-232 port. From there on, the port is
straight forward.

I haven't looked at it for quite a while but I'll poke around the Linux sites. I forget what platform the H port was for. Also, Host might help with a very limited scope first step if it were presented right. At least a little carnal knowledge would be required. A fixed address bare bones bootloader might be doable with all the embedded Linux info available. Handling the flash is kinda touchy. Hard to recover if you screw up. As soon as I get some time...

Regards
cww

We happen to have several WinPLCs that could be released to someone serious about a Linux port. If you have a flash method and bootloader plan, I think I could persuade the Powers That Be to release them. Contact me via email as bbaker at priefert.

Hold that thought.... I am interested enough to do the digging, but I am shorter on time lately than I have ever been. I have a paying project that I can't even get to.

Regards
cww

I think Bruce was referring to the fact that they use mHz on their spec page instead of MHz for the processor speed. :>

Dear Sir,

This question has been raised a number of times and answered a number of times, which system should be adopted?

I think almost all PLC/DCS systems are good to perform the desired operations. The only criteria you must use are:

-> Price of the system which suits you
-> The system you can easily handle
-> Last but not least, the system you can get help and assistance from the manufacturer the most easily

Regards,

A PLC Programmmer

Having your control system blue screen on a weekend could really begin to stink.

Regards
cww

Hello Jeff;

Most large PLC manufacturers are now offering their own version of "WinPLC" systems. Here are a few examples:

From Siemens, the WinAC platform, either purely software or slot-PLC: https://www.automation.siemens.com/simatic/pcbased/html_76/produkte/pc -based/based.htm

From Rockwell, a purely software controller:
http://www.ab.com/programmablecontrol/pac/softlogix/ind ex.html

From Schneider, a slotted co-processor application:
http://www.schneider.co.uk/internet/pws/pws.nsf/luAllB yID/10B1ED8DD933B84A8025710A005514BE?open

Success of these controllers in the market has been mitigated, due to control engineers and technicians being wary of PCs and Windows software stability issues (have a look in the Thermal Overload section in this forum, for threads on PC reliability "that wouldn't die").

PLC hardware and software is designed to run 24/7/365 with no mouse/keyboard/screen interface with a user, only with process data. Basically same chips as PCs, but software implementation makes cyclic processing of the program efficient and robust. There are Linux-based applications being developped (look at opensourceforge.com, the puffin project, for example) but I have not yet seen one working in an actual industrial project (Curt will probably correct me on that!)
;-)

I have see a few applications of the WinAC slot-PLC running well, especially when external power is provided to the PCI slot-cards, so that the PLC application will still run even if the PC crashes or has to reboot.

Notice that you are only swapping one hardware platform for another. You will still need the programming software from the manufacturer, and since you have no access to direct I/O cards you will need to implement network distributed I/Os (Profibus/DP, ControlNet/DeviceNet or Ethernet I/O).

Hope this helps,
Daniel Chartier

For the record, the tiny C precursor to the MAT/plc I wrote was successfully applied in an actual industrial setting and worked reliably for years until the company went under. But there is
really no way of knowing what people are doing with the project, it's theirs to keep so they don't have to register or even say thanks.

But, more importantly, I wanted to add that some very large, very serious, printing press builders have gone past PLCs in favor of networked high capability racks running Linux, RTLinux, and a hard RTOS. And the post press equipment went from
Mitsubishi PLCs to Beckhoff embedded computers with all networked I/O. They claim it's more reliable. The investment at risk is staggering so I'm pretty sure they have done their homework. This is all German equipment. The networks are all important and PLCs simply don't do networking on this scale. Just a datapoint of the latest high value systems I've seen. I think it's the start of the post PLC era. The tower of Babel collapsing
on itself in favor of stuff that _does_ work together.

Regards
cww

In reply to Curt Wuollet: I have experience with a couple of PC based systems in a different application area.

#1 - With the systems from one supplier, they were well engineered and didn't use any hardware or software that was prone to failure. The PCs were diskless, fanless and used a QNX OS. Everything was designed for accessibility and had proper attention to cooling. The machines were very highly regarded by anyone who had to use or maintain them.

This company also had an earlier generation of product that used PLCs (which we also had). The PC based systems though were at least reliable as any PLC (and the software was far superior to the PLC based versions).

#2 - Another set of equipment from a competitor was also purchased which was somewhat more problematic. These were also PC based. However there were fan failures (followed by overheating), hard drive failures (the machines inherently ran under continuous vibration), and software problems (VB and MS-Windows based).

The difference between the two is one system was engineered for reliability, while the other wasn't. I doubt there was any significant difference in cost between the two though. I suspect that when most people think about "PC based systems" they think about ones like the second system, rather than the first.

As I have mentioned before, we had a discussion on this list back in 1996 where Dick Morley (considered by most people to be the "father" of the first PLC) said the following about the PLC: "It was even then a computer, but was not called that since it might scare off the user base, since they were not very 'computer literate' at that point."

I believe that for "PC based systems" to be better accepted, people will require a better understanding of what makes a system reliable. At this point though, the user base still isn't very computer literate.

In the past 10 years however commodity PC hardware and software capabilities have evolved and diversified. Making a PC based system that is equal in reliability to a PLC is becoming much easier and doesn't require exotic software designs. The decline of the PLC "rack" and the rise of Ethernet based networked I/O means that interfacing to industrial I/O has also become much easier.

I suspect that as a result of this, there will be a shift in the PLC market. For very small and simple systems, the PLC "brick" won't be going away. It's still very convenient and easy to install. For lareger or more complex systems though, the market will move to PCs.

These will not necessarily be immediately recognisable as PCs. They may be in nice plastic DIN rail mount boxes with all the usual brand labelling and logos from companies in the automation business. However, inside they will be PCs using commodity components. The rational for this will be the same as for the move to Ethernet based industrial networks. The cost and performance advantages will be just too big to continue to ignore.

As the hardware capabilities increase, so will the ability to take advantage of commodity software. As this happens, we will see things like web servers and databases becoming a standard part of any PLC. These will be used to store and analyse data relating to the performance of the machinery being controlled. The ladder logic part of a "PLC" will become a smaller part of the overall system. People in our business who fail to become more "computer literate" will find themselves being left behind.

The computer market evolved from mainframes to mini-computers, to PCs, and is now entering what I would call a "post-PC" era. This more or less describes the move from expensive proprietary hardware and software to smaller and less expensive proprietary hardware and software, to commodity hardware with proprietary software, and finally in the "post-PC" era to commodity hardware with commodity software. In the PLC market, we're still more or less stuck in the mini-computer era. I think though that the developmental forces are still the same in both markets. The evolution in the industrial market has just been slower.

That's why the fanless all in one mini systems available recently are so interesting. With a flash disk, you can have DC powered, no moving parts, low power DIN rail mountable system that will run any reasonable PC program and has good connectivity and lots of HP compared to PLC offerings, all OTS and at very low cost for capability. I would like a PLC type box for the cheap local IO, but one of these and a bunch of Wago/Beckhoff racks, for example, could handle some pretty large applications. Certainly into the "large" PLC catagory.

Regards

cww

Do you like sporks? I don't - but I might use one to eat a small pot pie. If I had to down a pot of soup broth and a T-bone, more useful equipment might be a spoon, fork, and knife.

I assume you're referring to Automation Direct's WinPLC. I've never used it, but get the idea based on their web site. It is a 40 or 100mhz CPU placed inside a PLC slot running Windows CE - like my cell phone. I'm a strong proponent of Automation Direct. This device looks very capable in terms of bang for your buck - particularly with small applications that require PID loops or complex math - or if you have a very specific application that you want to custom code in VB or C++ that can't run on a computer (arghh??). For the most complex fish hatchery in North America this makes absolutely no sense.

To the best of my understanding those types of systems are uncommon and unlikely to ever really catch on, just like softPLCs running on PCs. Control system experts are mostly diehard PLC bubbas. The convergence is taking the form of more sophisticated next generation PLCs. General PCs can't be touched in the SCADA alarm and control arena. It makes sense to go in the direction of the industry standard, for future maintenance and upgradability, if nothing else.

Keep us informed on your progress.

----
Nathan Boeger
Design Simplicity Cures Engineered Complexity
http://demo.inductiveautomation.com

They do work, but quite honestly we removed the one we had in an installation and replaced it with a straight Automation Direct DL(something_or_other_that_escapes_me_now) processor.

Michael Batchelor
www.IndustrialInformatics.com

I've spent 10 years of my life working on Control & Automation, and never heard about that system. I'm not saying that is not a good system, but definitely I will prefer a PLC based system.

I think that you could give us more data about your process, and then we could help you to find a good platform.

Well, if you're using WinPLC to be the generic, as in Programmable Automation Controller, or PAC, yes, this is commonly used in industry. Examples include Rockwell's Contrologix, the actual AutomationDirect WinPLC itself, Advantech's line of PACs, National Instruments' line of PACs, Opto22's line of PACs, and many more.

Since fish only die once, I'd recommend being conservative on your design. If your engineering consultant is recommending a design, you might very sincerely consider going with it... after all, what the heck are you paying them for?

Walt Boyes
Editor in Chief
Control magazine
www.controlglobal.com
blog:Sound OFF!! http://www.controlglobal.com/soundoff
_________________

Putman Media Inc.
555 W. Pierce Rd. Suite 301
Itasca, IL 60143
630-467-1301 x368
wboyes@putman.net

Cumon Walt, he's not looking for a broad stroked BS answer about PACs, he's asking about a specific product line for a specific application that was recommended by his consultant. The product is for really small applications (that's being polite). His application obviously doesn't fit that mold. Besides, a Windows CE based control systems hardly fits into the same category as a Control Logix PLC.

OP was given a poor recommendation by that engineer. That's further evident by the sheer number of experts that shot down the idea so quickly.

----
Nathan Boeger
http://www.inductiveautomation.com
Total SCADA Freedom

I don't think there's anything wrong with the basic idea or PC control in general, but you would want much more robust software. And unless it was very efficient software, more horsepower would be handy to have.  We still need a good Open PLC class hardware platform to build on.  I'm surprised some of the newcomers trying to claw their way into the market haven't tried an Open approach. It would have better chances than more of the same closed, expensive, BS.

Regards
cww

I agree, particularly in theory - that's why I stressed the clunky part being Windows CE, not a PC.

There are lots of reasons why PC based controls would be better. I like the idea of an open approach as well.

I was trying to focus a response around actual implementations. An E Machine just isn't suited for industrial apps - the fans and the power supply, non-shock mounted mechanical hard drive, needs to be resilient hard reboots, etc, etc.

An industrial PC could certainly be made from commercial off the shelf hardware. It could be the best, easiest to use, most powerful and stable device ever, that could be modified at runtime - superior to PLCs in every way. Unfortunately nobody makes that software yet.

----
Nathan Boeger
Inductive Automation
Total SCADA Freedom

I wouldn't go so far as to say nobody. We don't have a strong vertical that can provide a complete easy to use package. The problem isn't the technology, it's that everyone goes for the monopoly market rather than grow an alternative market. Things change so slowly in automation that even the perfect product you mention could only gradually filter in, and that's not what people want in a new product launch. It's far easier to just do more of the same, no matter how bad that is. That's why monopolies tend to stay monopolies.

Regards
cww

I agree that it's an implementation issue not a technology one - that's been the case for years. I think the problem is that nobody (in a wide sense) seems to trust the idea because of failed crappy implementations in the past - and all the half baked open source projects that you wouldn't want to run your plant.

I, for one, would like to see such a technology. IMO it would take a monster push, like a Google project to make that happen overnight.

That "nobody" comment was about a piece of software that would make a PC into a "better" general purpose PLC. Highly possible, but a monster task. Do you know of any software that does this?

----
Nathan Boeger
http://www.inductiveautomation.com
"Total SCADA Freedom"

Hi Nathan

Nathan Boeger wrote: "I agree that it's an implementation issue not a technology one - that's been the case for years. I think the problem is that nobody (in a wide sense) seems to trust the idea because of failed crappy implementations in the past - and all the half baked open source projects that you wouldn't want to run your plant."

Actually, most automation projects are half baked, the FDTTW thing (First Damn Thing That Works) and you usually get every part of the solution that can be modeled with relays. :^)

Systems that last a few years often gain refinement, but if it works, people tend to leave it alone. But, you should think through what you are saying.

A few k of machine code on a minimal computer tied to some fairly bush league applications on a PC does not constitute a gargantuan task.  Many single hobbyists working in isolation have done more on a lark. And the parts are all there. The amount of free code available is staggering and you have the parsers and compilers (and parser makers and compiler compilers) and screen builders and all kinds of examples of pretty much every part.

On reflection, with the rare perspective of a few years around such a project, there are a few issues.

Everybody has a different idea of what it should look and work like. The desire to produce a be all, end all,  product. More is better.

This has lead me to a conclusion that the commercial offerings succeed most often because of _lack_of resources. They have a specification, a time and a budget. And to the extent possible, they stick to them.

Also, we have to separate the PLC from the rest.  Automation people are almost always talking about the rest. When you are an AB fan or a Siemens fan it has almost nothing to do with the PLC. In fact, quite often in the past and perhaps even now, they would argue about the merits of vendors who were running on the _same_ PLC.  Example: Koyo. 

All PLCs do the same things, in much the same way, and the rest of a product could probably be configured to run on a different PLC if they wanted to do that.

SoftPLC has succeeded to some extent , IMHO, by picking A single target and emulating that faithfully enough to demonstrate that it was nothing special and could easily be done by more powerful computers.  They have progressed beyond that, but that success produced the foundation, the basis, and believers.

A PLC is so much less complex than everyday objects, that a greeting card is probably running more firmware.

The software and hardware built around the PLC need to be bounded by a PLC design and not a moving target.  <br> The interface between them has to be finite and well planned.

The tools are where free and open can really shine. These are, after all pretty, much standard PC applications and there are a lot of people who are pretty good at that.

These are not technical problems and are not insurmountable.  But to do so will require a different structure than what has been tried.  And commitment to that structure. Perhaps  two groups.  A small disciplined group for the core PLC and the rest of the community. Or perhaps a benevolent dictator. Or perhaps a sponsor with 49% control. I am absolutely certain it can be done with the right organization.  Just my thoughts on the subject.

Regards
cww

You have by this time heard a number of opinions on the WinPLC. To answer your questions more directly though.

Q: "Are WinPLC systems commonly used in general industry?"
Answer: No. This is a niche product sold by a minor vendor.

Q: "is this still an emerging field?"
Answer: No. The market shows no sign at this time of changing to this type of product.

The "WinPLC" is just the brand name for Think & Do's software when embedded into a special version of Automation Direct (AD) CPU. Think & Do is a company that has been selling "soft logic" software (emulates a PLC on a PC) for a good many years now. Their particular niche is that you program it in flow charts instead of normal ladder logic. The WinPLC simply embeds that software into a board that replaces a normal AD CPU (DL205 series).

Here's a link to the actual product.
http://web1.automationdirect.com/adc/Shopping/Catalog/PC-b ased_Control/WinPLC_Products/H2-WPLC3-EN

I have some experience with the normal AD PLCs, and have no complaints about them. They are the marketing name for Koyo, which is a Japanese company who has long made hardware sold under the TI, GE, or Siemens names. I haven't anything to say against Automation Direct (Koyo), but the WinPLC is a specialty product, and not part of their main product line.

The Think & Do software is fairly rare, and I've never laid eyes on an actual installation in either a WinPLC or in a normal PC form. Someone who had used their software some years ago though told me that although the flow chart programming is easy as a general concept, it is actually difficult in practice to do many normal PLC type operations with it. That is, you end up with a long and convoluted flow chart to do something which is very simple in ladder logic. I would expect to see higher programming costs unless you are dealing with someone who has a lot of experience using the Think & Do software. In addition, while a typical industrial electrician can read and understand normal ladder logic, they are extremely unlikely to have even heard of Think & Do flow chart programs, let alone have any experience with them.

Another thing about this, is that it is really just another (unusual) PLC CPU. It isn't a "base" to a solution any more than any other PLC CPU would be. You will still need the rest of the PLC rack, a SCADA, and a control network. What you should be talking to your engineering consultant about is PLC and SCADA brands based on the features you need, availability of spare parts,
cost, etc. Something that might matter more to your application than it would to a typical factory would be the humidity and temperature tolerance of the hardware. I assume that a control network (to sensors and actuators) will be an important part of the system. You should be trying to use one which is supported by the greatest number of relevant vendors possible. The control
network can be the most difficult part of the system to replace in future.

One of the previous replies mentioned problems with Windows CE locking up regularly in WinPLC installations. While I can't claim any first hand
experience with WinPLC, this problem with Windows CE is not uncommon in other applications. The main market for WIndows CE is in mobile phones (where they are a minor player in the "smart phone" niche) and it is notorious for this problem there.

Folks, what the original poster (Jeff) failed to mention is that we (being the other staff) already have an example of implementation: a small-scale water treatment system and fish hatchery controlled with WinPLCs and Phoenix Contact’s Think-N-Do software (formerly Entivity Studio). WinPLCs serve to execute the control logic, and a PC (connected by Ethernet) doubles as both HMI screen for operators and as a programming platform (requiring reloading of control logic onto the WinPLCs if changes are made). In 4 years of operation, we have never had a Windows CE system crash (how foolish is that?) – other than from inappropriate use by operators (storing excessive data from field instruments in the flash memory) or power fluctuations (requiring all equipment to be rebooted). This system was a fraction of the cost of traditional PLC hardware and software, very stable and reliable, and incredibly easy to learn – the flow-based programming is an asset, and certainly not a detriment. It would indeed take a systems integrator with more than 1 or 2 functional neurons LESS time to program a flow chart for process control than to write from scratch in relay ladder logic. It is certainly easier for non-programmers to understand, implement, and troubleshoot during operations. There are more examples in industry of successful implementation of TND and WinPLC for process control: HP’s (Agilent Tech.) R&D campus in Santa Rosa, CA, microbreweries in both California and Alaska, water wastewater treatment plants in Germany and the US, and metal finishing industries, and handful of others, to name a few. If you truly want to lean more, see:

http://www.automationnotebook.com/AppStories/usersolutions appstories.html

Control in the fish hatchery setting is not all that complicated – the fish husbandry is more complex than the process control. Much of modern hatchery equipment comes with integrated controllers, where a distributed control and network system is ideal to monitor and optimize performance. The basic things that are controlled in hatchery setting include timers, pumps, and automated valves (using simple PID loops to control temperature and water flow via pump speed with VFDs). Most other things are simply monitored and alarmed (water chemistry and water levels). WinPLCs and the TND program are more than adequate for such applications.

Whether or not this whole system is suitable for a larger-scale fish hatchery rearing multiple species is a loaded question. It is true the TND software is not well known, requires specific hardware that has limited sales distribution, and comes from a smaller manufacturer with fewer third-party support options. However, larger consultants also have relationships with the big-name control system manufacturers and distributors, where they stand to lose money if they have to step outside their comfort zone for new hardware, or have staff learn a new software program for a client. We’ve demonstrated success, at least on a small scale, and have every reason to believe it can be scaled up to something larger.

For more information about our application, feel free to contact me off this post.

Jeff,
Like most others I wouldn't like to rely on a PC based system. A PC is fine for display if it crashes the PLC caries on. We have used an inexpensive product from Opto22 on several recent projects. The software is free and what's really nice has no licence to worry about, will run on any old PC. Programmed in flow chart which takes a bit of getting used to after ladder but seems to be easy for a Non ladder engineer. check it out at opto22.com

Roy

Jeff,

I think what is getting lost here is who is your user and under what conditions will the control platform run? PLCs are great for almost any industrial controls engineer and work great is a wide range of environmnents. But if the controls are indoors in a protected environment (even if it's 0 degrees outside) and the person using it does not know the first thing about ladder logic, then you have more options. Especially if flowchart progamming is used because it it more intuitive for operators who are not controls engineers. Ladder, however, is a more universally accepted progamming language for operators that have PLC experience.

PLCs might be the safe choice, but PC-based control has established enough runtime and customer base to warrant a serious look. The open platform concept simply cannot be beat either. PLCs are notorious for trapping users on proprietary networks and expensive support contracts.

PLC and PC-Based Control Vendor

I would only ask: What you can possibly
consider open about such a system?
Running shrinkwrap binaries on a closed OS?

Regards

cww

All,

I posted my question and promptly left town on a trip. I was amazed to return and find so many replies. Thank you all for your varied and sometimes colorful responses.

At this time we have chosen to stay with industry standard PLC systems. While the WinPLC concept apparently holds significant potential there is such a limited track record that it would be imprudent for us to head in that direction.

Thanks again to everyone who responded to my inquiry.

Happy Holidays,

Jeff

And again, we maintain that there is indeed an abundant and varied track record and history to successful use of the WinPLC system for industrial control. All you need to do is simply look at it...
And it is neither imprudent nor impractical to embrace such a system, particularly when a successful identical application to what's planned has already been demonstrated.

But Happy Holidays, nonetheless...

There seem to be two assumptions appearing throughout this thread.

1 - PCs crash routinely

2 - PLCs have to be programmed in ladder logic

We have been installing off-the-shelf PCs in industrial applications for more than a decade. It is made clear to all staff that no, you don't use these PC's for games, DVDs, word processing, or any other entertainment. They are a mission critical corporate asset and are to be treated as such. Using Windows 3.1, 95, 2000 and XP with VB applications we have never experienced problems with PCs spontaneously crashing in the field when they are left to do what they were programmed and tested for.

Since ladder logic programming requires a different mindset from VB or C programming, we have chosen to develop PLC applications for our customers using the IEC languages. In particular using Structured Text (Pascal like) and Function Block Diagrams (graphic design). A VB or C programmer can be cross trained in these two languages far more easily than in ladder logic. Many routines are easier to program and read in FBD than in VB or C. If you are looking for non-ladder logic standards, this is the way to go.

Victor Robert
Key Concepts LLC
var@KCLGlobal.com

Victor - respectfully,

1. PCs do crash routinely compared to PLCs. They are not designed to handle: unanticipated shutdowns, mechanical vibration, heat, etc. They have way more moving parts. If the fan in your power supply gets dirty it will eventually seize - killing the machine. There are too many specific examples to list. PCs are also most often connected to your industrial I/O via some sort of network that can go down. This opens up another can of potential problems that a PLC connected to a backplane connected to I/O modules doesn't have.

Mission critical corporate asset or not, Windows boxes lose their reliability over the years. What kind of maintenance do you ever have to perform on a PLC?

2. The difference between implementing your PLC program in: ladder, C, assembly, block diagrams, flowcharts, etc. is of little consequence here.

The most obvious issue was the size of OP's project versus what the CE based WinPLC was designed for. After all, this is one of the most complex fish hatcheries ever to be built in North America.

----
Nathan Boeger
http://www.inductiveautomation.com
"Total SCADA Freedom"

In reply to Nathan Boeger:

NB: "PCs do crash routinely compared to PLCs"

MG: If you use poor hardware and software you will have a problem. If you use
reliable hardware and software you won't. A "PC" doesn't necessarily mean the same sort of computer you use to play video games with.

NB: "They are not designed to handle unanticipated shutdowns,"

MG: A journaling file system will automatically recover. A read-only file
system will not have a problem to begin with.

NB: "They are not designed to handle ... mechanical vibration, ... more moving parts ... fan in your power supply ... will eventually seize"

MG: Use a fanless, diskless, PC. There are no moving parts. Some PLCs by the way, have fans which seize and cause the PLC to overheat.

NB: "PCs are also most often connected to your industrial I/O via some sort of network that can go down."

MG: They use networks that were designed for PLCs. If this is a problem for PCs, then this is a problem for PLCs as well. Many PLCs these days use networked I/O. The local rack is disappearing for all but the smallest installations.

NB: "Mission critical corporate asset or not, Windows boxes lose their reliability over the years."

MG: Then don't use Windows, or is that too obvious an answer?

The WinPLC by the way seems to be taking a lot of flack because people see "Win" and immediately think "Windows - shoddy, unreliable, crash-prone, etc.). The company behind it might want to think about a re-branding effort where they drop all association with "Windows" and just call it a "PLC with flowcharts".

What he said!  They are converging and pretty soon you will need a score card to tell the difference. Check out the $200 Linux computer at
WalMart. 20 watts working, 2 watts snoozing. Throw away the drives and use Flash and you  have a  pretty good candidate. And made in the hundreds of thousands, the reliability should be _better_ , better than the Micrologix I've
been using in any case.

Regards
cww

In reply to Victor Robert: You used MS Windows 95 in control applications and "never experienced problems with PCs spontaneously crashing in the field"? That's amazing considering that MS Windows 95 had an overflow bug that caused it to "spontaneously crash" every month or so unless it was rebooted first. It took a few years for people to figure out what was happening, as it being MS Windows 95 few people were able to keep it going even that long.

As for there being assumptions "throughout this thread" that PCs are inherently unreliable, I think you will find that a few people were saying that PCs can be reliable provided you use hardware and software selected for their reliability.

In addition to Michael Griffin comments: Another application where PC are used 24x7 is model predictive control. It is a computationally intensive task, especially if it is nonlinear MPC with first principle based process models, and that is why it usually resides on a PC. An exception to this is parametric MPC in which the solution is precomputed off-line.

Regards,
Andrey Romanenko // CIengis

Hi,

A PLC is a means of bullet proof automation. That's its job.

SCADA is a means of non-technical staff to watch and possibly affect the process environment, e.g. Supervisory Control And Data Acquistion. That's its job.

A PC is a thing to type letters on a few hours a day and then play cards. It will go down at some stage and you will lose some SCADA historicals, your proccess should not be affected. What do you expect from a $1.99 control solution? That's its job.

We have had Windows 95 PC's in operation up until this year when the final one was replaced with an XP Pro PC. Simply because they were reliable and the customers had no desire to change something that worked. We never experienced a problem with monthly crashes as suggested.

My use of "crash" in my earlier post was in reference to the software, not the hardware. If you are going to use exposed electromechanical devices such as fan motors in harsh environments, then protect them appropriately (climate controlled control room) or use solid state devices. Whether PC or PLC, why are you filling it with dirt? Either will become less reliable. Come to think of it, how are you treating employees? They will become less reliable too in such environments.

The idea that it "becomes less reliable with age" applies to most manufactured and living things on this planet. However, unless you are dealing with a virus, software is exactly the same set of bits you installed five years ago.

I don't understand the suggestion that an Ethernet network would be more or less reliable based on which devices (PC's or PLC's) are connected to it. Perhaps you could elaborate. Its a design given that you don't connect your corporate business network to your control network.

Regards,
Victor

In reply to Victor Robert: I was referring to the infamous 49.7 day bug. Microsoft Windows used a 32 bit counter to track the number of milli-seconds since start up. After 49.7 days (4294967296 / (1000 * 60 * 60 * 24) = 49.7) the counter would wrap around. This in turn would cause a crash.

The following is a news reference from time when this was discovered (approximately 4 years after Windows 95 was released). Windows 98 was also affected. If you do a search for other reports on this issue, you will find that few people considered this to be a major issue, as they expected Windows to crash much more frequently than that anyway.

http://www.news.com/2100-1040-222391.html

I'm trying to avoid anecdotal stories of PCs lasting for several years - sure they can, but statistically, many will fail. Consider server rooms that are clean, air conditioned environments. You're constantly replacing power supplies and hard drives - that's why you put in redundant setups. You nailed that one on the head - electromechanical devices.

As far as software, you're living in the same electromechanical world. The bits are NOT exactly the same after several years of operation. Think hard drive fragmentation, defrags, Windows opening and retaining a file lock on the same .dlls, etc. Can you run a controls environment on the same Windows PC for years? Sure. Is it the same? No. Should you expect to have to rebuild the machine in a 5 year lifecycle - I hope you plan on it. This is aggravated by a few points. One, a hard power cycle or brownout can cause serious problems. Keep your UPS batteries maintained because they die over time (chemistry). Two, maintaining security patches and updates has a history of breaking industrial software. This is a much smaller consideration for PLCs than PCs.

Why the network makes PCs more susceptible to problems than the PLC. This is due to the fact that your important things are plugged directly into I/O modules in the PLC. No network required (besides the wire). This is done by design because the PLC is more reliable for 24/7 operation than the PC. This allows production in a typical setup to continue without the Ethernet network - minimally, part of the process could work. That is changing as everything becomes IP based. For the PC, presumably nothing useful will work if the Ethernet network is down. Ie, you could have a modem plugged in to send a page/text message, but all the PC knows is that its network is down.

Make sense?

----
Nathan Boeger
Inductive Automation
"Total SCADA Freedom"

Some thoughts on selecting PC vs PLC...

Many if not most applications today use a display with touch screen or keyboard/mouse for the user interface. The most cost effective solution for this hardware is the PC. Although most of us probably shudder at the idea of what we might get for $200 at WalMart, the cost of name brand equipment is not much more. The alternative is to use hardened devices from the PLC vendors.

The biggest advantages to the PC are the cost and the fact that I am confident that in ten years I will be able to find a replacement at almost any electronics retailer on Main Street and be able to load my CD and be up and running in a few hours. I would fully expect the manufacturer of a low volume, specialized device to tell me it is out of production.

Comparing the average PLC to a PC with 3GHz Pentium, 2GB RAM, 300 GB disk, database engine, network connectivity, etc. is like comparing apples to watermelons. They are two very different products.

If you already have a PC in the application, do you need to add a PLC? It depends entirely on the application. Networked I/O modules can easily be added to the PC with common Cat5/6 Ethernet cables. If your application is farming, and it really doesn't matter if the animals get fed 5 seconds later on Mondays and Fridays, then you probably don't need a PLC. If you are manufacturing many parts per second, then you do need a PLC.

The down side to adding the PLC is that you add a level of complexity to your application. Now you need additional skills to program and to maintain the system, adding initial cost as well as ongoing cost of ownership. Programming skills for a specific PLC, particularly an older one are far more difficult to find than general VB/C skills.

The up side of the PLC is that you are free to improve your PC hardware and software (user interface, faster processing, reporting, charting, data storage and analysis) knowing you will not adversely affect the underlying real-time process.

There is no "best" solution that will cover all automation applications.

Just as a note:

You can buy the mainboard used in the $200 WalMart PC for $60. And I don't think you are accepting any more risk than the $100 PLC you get from AB. The AB boards are Korean and the PC2500 is by VIA group partner Idot in Taiwan.

VIA makes millions of boards a year.  I'm fairly sure they know how.  The  only hangup with the PC2500 is that it uses a fan on the processor, but a little package engineering to transfer the heat to the skin would take care of that.

The boards are sold out at least till after the holidays or I'd have one. At $60 it's an incredible bargain if you've priced SBCs.  Intel also has a board out in the same ballpark for price and power.

No, these aren't the supercomputer class needed to run Vista, but they have vastly more compute resource than most PLCs.

Regards
cww

In reply to Curt Wuollet: VIA hardware is used in quite a few name brand "industrial" rated systems because they have versions with very low power consumption, fanless operation, and small size. They make boards themselves and other companies also base their designs on VIA chips (including VIA x86 compatible CPUs). The board you are referring to has a fan because it uses a faster CPU (fanless boards use lower clock frequencies to cut heat output).

Quite a few people reading this probably have VIA boards or VIA based boards in their factories with the name of some industrial automation company on the case (e.g. in many panel mount PCs). VIA is probably better known for their chipsets used in many mass market PCs, but they are also the leader in the low power x86 market. Intel however is also coming out with a new lower power x86 CPU and chipset design targeted at the same market (embedded PCs, which is much bigger than just industry).

A typical low power fanless x86 PC today runs at about 800MHz, and is probably equivalent in processing power to a higher power CPU running at about 600MHz. That isn't very fast, but it's more than adequate for a lot of embedded tasks. The motherboard you referred to has a fan and runs at about twice this speed. Typical power consumption for an entire low power motherboard is about 14 watts, as compared to close to ten times that for a high power Pentium CPU alone (which is why the Pentium CPUs need fans).

The PC you mention with gOS (Linux) is $199. The equivalent PC is available from the same source with MS Windows Vista Home Basic for $278 (40% more). That PC isn't offered with MS Windows Vista Business, so it's hard to get a clear idea of what that would cost. However, Dell charges $90 to upgrade a new order from MS Windows XP Home to Professional so it's probably reasonable to assume a similar price differential for Vista. So a price of $368 (85% more) for a PC with MS Windows Vista Business would be a better comparison. If you look at it that way, then the $200 price doesn't look so anomalous. This by the way wasn't supposed to be an accurate price comparison of Linux versus Windows. I am just trying to point out that the $200 price tag doesn't mean they used hardware that was any worse than any other low end PC.

Actually, I think this is part of a trend, If they can build a green PC for less, the only limitation is bloatware. It's just better and easier all around if your PC doesn't dim the lights and double as a space heater. I think this is another case where MS is doing us a disservice with their incredibly inefficient software. If it won't run Vista, it won't sell, even if it's more computer than it takes to run anything within reason. The glimmer of hope is that with Linux on board, Walmart can't seem to keep them in stock.

Regards
cww

I have read that Microsoft plans to release a "lite" version of XP next year. (What is taking them so long?) It is supposed to be used on "low end" PC's and have a relatively lower cost. They are presumably trying to compete in this low cost, energy wise market. This is a good thing for dedicated industrial systems that must run Windows.

In reply to William Sturm: The following is a bit of a long story, but I think the background is necessary to explain what I think is going on.

I believe what you are referring to is a version of Windows XP that Microsoft is working on for the OLPC XO laptop computer. This is a small low cost laptop that has been developed by a charitable organisation as a dedicated educational tool for children in lower income countries (http://www.olpc.org). The existing software is based on Linux, with a custom user interface and application software foundation (it's customised for educational use). The target price for this laptop is $100.

Microsoft is very unhappy about this project because it doesn't use Windows and have tried (unsuccessfully) to get it stopped. The people who are running the OLPC XO project say it's an open platform, and if Microsoft wants to try to shoehorn their operating system into it, then nobody is going to stop them (although what Windows would actually accomplish without the XO educational software is questionable).

What has been in the press lately is Microsoft has said they will try to strip down Windows XP enough to fit it on the platform, and also develop Windows drivers for it (normally they leave that up to the hardware manufacturers). The Microsoft PR people have been saying they expect to have something some time towards middle to late next year (which is the time you mentioned). The head Microsoft engineer for the project though was interviewed by the press where he cast doubt on whether this is feasible or if it is, then when they might have something. Microsoft has asked OLPC to beef up the hardware design to accommodate Windows, but the OLPC organisation has said that idea is a non-starter because they are already over their cost target.

So at this point there is a lot of question as to whether "Windows XP Lite" project will continue. At present it exists mainly due to internal politics in Microsoft as it was started as a knee-jerk reaction to the OLPC XO.

If Windows XP "Lite" ever comes into existence, it will be restricted to certain applications in cost sensitive markets. You won't be able to buy it for general purpose use. It's strictly intended for use as a marketing tool in trying to prevent the use of Linux in high profile applications and will not be for general sale. Microsoft will give it away for nothing if necessary, but they don't want to undercut their normal revenue sources. There's no money for them in that market, but they are concerned about protecting their effective monopoly in the business PC market where they make most of their profit.

The Windows XP "Lite" idea is being rushed out to meet a threat that has caught Microsoft flat-footed. At first there was just the OLPC, but in the past year there have been several other very low cost and low power computers which have come out (e.g. the Asus Eee laptop and the Everex "Green PC"). Both the Eee and the "Green PC" (so called because of the lower power consumption) are or will be available with Windows, but only in higher cost versions with beefed up hardware.

The current version of Microsoft Windows (Vista) has so far been a disaster. Running it on normal high power PC hardware has caused numerous complaints. Trying to fit it into the new class of small, low power, low cost computers is out of the question. On the other hand, keeping Windows XP on the market can't be anything more than a stop gap because its age is showing. For example, the stock version doesn't even support SATA hard drives, which have become standard hardware in modern PCs.

Microsoft has already started work on the replacement for Vista, but that isn't due for a couple of years yet (assuming they manage to meet their schedule). It is possible that they could use that opportunity to come with both "lite" and "full bloat" versions of Windows.

The problem with a "lite" version though is that too many people might actually want it. Microsoft uses Windows as a platform for getting their other products into the market. For example, the biggest thing they are trying to push at present is their DRM system (copy protection for entertainment). If they can get their DRM system entrenched in the market as the de facto standard, then they hope to collect royalties from music, movies, DVDS, etc. which use it. The DRM system has been a massive headache for hardware companies trying to write drivers for Vista (which is one of the reasons for Vista's poor hardware support record) but it's all pervasive in Vista and so isn't easily removed.

Stripping the "bloat" out of Windows Vista would mean stripping out DRM and a number of other strategic technologies which Vista was supposed to deliver to Microsoft. A version suitable for use in industrial applications is therefore unlikely, as that market is too small to interest Microsoft. Microsoft's idea of "embedded" involves entertainment systems for things like delivering video or music over the internet. These all involve heavy use of DRM, which is what Vista was created for.

It is possible that Microsoft will reverse course and write off Vista as a bad idea. That might require a major shake up in upper management though, and I don't think they're that worried yet.

If you want to see how small a Windows-like *could* be, have a look at ReactOS. This is a clone of Windows written by a group of hobbyists. The ISO image is only 27 megabytes. It's supposed to be more or less equivalent to Windows 2000, although I've never been able to get it to do very much other than crash (running it in a QEMU emulator). Compare that to Windows Vista which is more than 2 orders of magnitude larger.

Hi Michael,

MS should be worried then, it seems they've nailed the core of Windows, the Blue Screen Generator. The rest should be easy, just throw in all the miscellaneous crap you can find until the PC slows to a crawl. :^)

Regards

cww

In reply to Curt Wuollet: I think ReactOS is just trying for MS Windows 2000 compatibility. If someone really needed MS Windows Vista emulation, I'm sure they could just run it on a slower computer to get the same effect.

I'm not sure what the rationale behind ReactOS is. They use parts of the Wine libraries for a lot of their MS Windows API emulation. However, Wine on Linux seems to actually do a better job at running MS Windows programs than ReactOS does. For example, the AD DirectSoft programming software won't even install on ReactOS (the installer doesn't seem to even start). In Wine on Linux though, the DirectSoft package installs and runs (with some fiddling, some features not working, etc.).

But if the people writing ReactOS are having fun, I suppose that's all that really matters to them. I wouldn't use it for any real work though.

Hi Michael I had a hard time thinking of what their rationale might be as well. Perhaps they recognized that W2K was about where Windows began to spin out of control and they can capture the market for something reasonable. There are a _lot_ of business people still using W2K, waiting, perhaps, for the next stable (relatively speaking)  version. Soon to be outcasts if they don't buy new everything.

Regards
cww

It would be even better if the industrial vendors would do the ports so that there isn't anything that _has_ to run Windows. Having to compete on merit is about the only thing that could get the Redmond crew to pay attention to automation needs. If even one major announced a Windows free toolchain and Open protocols, there would be sweeping change in the automation arena.

Regards
cww

Sorry, Curt. I didn't mean to put down the product; I don't know anything about it. Its just that the terms "$200 PC", "WalMart" and "Industrial Automation" in the same sentence will take some getting used to, just as "Made in Japan" has had vastly different connotations over the past 50 years.

Nathan, your point "but statistically, many will fail" might be more accurately stated as "statistically, everything will fail". Light bulbs and automobiles fail, but we seem to keep on buying and using them regardless. If its a mission critical application, we always install two or more redundant PC's. Its slightly more involved than changing a light bulb, but takes about the same number of engineers :-). They can and will fail, but that is just part of doing business. We will replace PC's every 3 to 5 years of 24/365 use whether they need it or not, usually in conjunction with a software upgrade. Using name brand products, our experienced failure rate within that period has been extremely low. An advantage is that we have a "new" system every few years and can re-start the obsolescence clock (excluding I/O hardware).

Regards, Victor

...More thoughts on product selection.

We choose what we are familiar with. Any of us could get into any car on a rental lot, figure out the seat and mirror adjustments, and be driving away in 60 seconds. Now put a full size John Deere tractor, an 18 wheeler and a bicycle on the lot and apply the same 60 second requirement. It is clear which of the vehicles the farmer, the trucker and the cyclist will choose. Did any of them choose the right or wrong product? No, given the objective, but their selections were based entirely on personal comfort level, not technology evaluation.

If you ask granpa, who has owned and driven only full-size Fords for the past 60 years, what kind of car you should buy, are you limiting your possible outcomes?

If the objective is to get the product programmed and running by the end of the week, is there any doubt as to which method the C programmer, the VB programmer or the ladder logic programmer will choose?

If you are asked to recommend the best widget for a job, will your selection be one of the 5 products you have worked with, or could it possibly be one of the 10 you have never seen before?

Another consideration is that the objective of any project is to get it done on time, within budget and make everyone involved look good. If you tell the J programmer that he must program in the K language because it is the "best" choice, will he buy in to the project, or will there be some subliminal desire to prove that this was the wrong decision? The team has a better chance of getting to their goal if they are all facing in the same direction.

No easy solutions, but that's we why get the big bucks, right?

VR

Well put - Good points!

----
Nathan Boeger
"Design Simplicity Cures Engineered Complexity"
Inductive Automation

I disagree with the point behind your version of my statement. I was pointing out that the MTBF on an industrial PLC is SIGNIFICANTLY greater than your off the shelf PC due largely to electro-mechanical parts and design specifications. That's important - you can't adequately summarize it with "everything breaks".

As to redundant PCs - we're discussing a specific implementation, not vague theoretical applications. Specifically, using cheap Automation Direct WinPLCs to control one of the most complex fish hatcheries in North America.

To set the record straight - on the theoretical approach, I think PCs could do much better for controls than PLCs - PERIOD. However, the software/implementation needs a lot of work. We're certainly not there yet with random non-programmers quick C++/VBA jobs. A heck of a lot of complexity comes with redundancy and clustering.

----
Nathan Boeger
Inductive Automation
"Total SCADA Freedom"

I feel that both the PC and the PLC scada will have their palces in the Induatrail automation. However our experience is that in PC based systems Hardware and sofwtare maintanace / upgrades is still a issue. In every place PC is used it has been replaced after a maximum of five years as either the hardware or the software OS is not maintanable. This compares not so well with PLC hardware.

However we are getting machine control applications in the recent past where PC is a necdcessity because of visualisation / database requirements and forms part of the control system. Here the problem is that although we use the PLC for critical areas in the machine the total system reliability is the reliability of the PC.

I am yet to get a solution for this problem amd would be glad if somebody can suggest.

Real time PLC development software is still expensive on the PC. Not to speak of the motion control on PC.

The really interesting part of the mini mb push is
that they hear this and are specifically setting up a longer life-cycle with a 5 year minimum. Much
better than a new generation every 6 weeks. I'm glad someone wants to stop the madness.

Regards

cww