Soft Plcs

[Justin27 0]

What is the groups concusses of soft plcs. Love them or hate them? Application specific ? Justin

[TimWilborne 108]

Personally I am not for Computers in an industrial environment although they have come a long ways in the last few years in terms or reliablity. I just feel they still ahve a long ways to go as far as software.

[TConnolly 13]

Most soft PLC programs cost just as much as a PLC processor, if not more. Either way, you have to purchase the IO. Just as well put a real PLC processor in.

[Ron_Smith 13]

We've got 4 computers running VB6 with Adlink/Opto22 I/O cards. The sole purpose is collecting test results from the inspection end of a couple of our production lines. I would NEVER consider this setup for any kind of machine motion or process control. Just not reliable enough. Sometimes the keyboard stops responding... sometimes it's the mouse... sometimes Windows just locks up for the heck of it . Ron

[TimWilborne 108]

Wow I would have thought more of the die hard PC control guys would have chimed in on this one. Back in the 90s there was a big push for PCs on industrial equipment. Is that dead?

[Sleepy Wombat 27]

Thats because they are still fighting and ironing out the bugs with the systems they sold in the 90's, oh and still waiting for the dang things to boot up.....

[Spanner 0]

Not only that but I think If you know what you're doing, you can pretty much do anything with a PLC that you can with a PC... within reason. Anything extravagant can be done on a HMI PC such as a WinCC or Intouch server. By offering this interface facility, when the HMI inevitably crashes, the process being controlled is still quite happily working away with the PLC while all the pretty, fancy and gadgety things you'd want a PC for can be run seperatly on the HMI. That's my opinion anyhow.

[kb9ttx 0]

Our business is centered around mobile robots; laser guided vehicles in particular. Despite the fact that our products move throughout factories and warehouses without the aid of an operator, we do not use PLC's. In fact, each vehicle has its own onboard multiprocessor computer. The vehicles communicate wirelessly with a central Windows-base server which manages traffic, diagnostics, etc. We've been using this scheme for years (20+) without the emergence of the conjectured worries of the PLC VS PC debate. The SoftPLC debate is really about whether or not a general all purpose computer and operating system can be augmented and configured to safely perform the duties of a PLC. In reality, the PLC is really a small dedicated computer running a propritary operating system. In time, the market will decide this debate. PLC's will probably always exist for those applications to which they are best suited and SoftPLC's will pick up new applications. In fact, I'd argue that those applications which are small and communicate via EtherNet will be the best candidates for SoftPLC deployment.

[TimWilborne 108]

Read post "6189-fpabagp Video Driver Card, Allen Bradley video driver card" under the AB section This is probably the main reason I haven't tried any. It is such a consumer driven industry that they have to keep coming out with something new to keep people buying. Anyone tried to order parts for a 20 year old computer lately. Last time I checked PLC-5 and SLC replacement parts are still readily available. Heck you can still get PLC-2s and they have incentives for upgrading these. Also Rockwell has a group dedicated to finding replacement components for theses so if a purchase item for one of these quits manufacturing a part they will find a replacement. Thats well worth it to me I would debate this statement. Just look at the new Logix platform. I can't think of too much you can't do with these that you can do with a PC. But yes, they are pretty much dedicated PCs but that is what makes them reliable

[kb9ttx 0]

I should have qualified my opinion. Automation was primarily the endevour of companies with deep pockets who were looking for economies of scale or controlling large difficult processes. Now we can readily see small scale automation in the "new" American manufacturing sector... micro-manufacturing where output is in terms of tens instead of thousands. In these small scale manufacturing operations, a PLC could be seen as overkill (especially an expensive AB PLC) when a simple remote I/O over EtherNet or Profibus connected to a PC and coupled with a safety relay, or two, can do the job. Personally, I can't see investing $5K or more in a system that only has 16 I/O or so. Now in larger systems, I'd agree that a PLC is the best way to go at this point.

[TimWilborne 108]

Thought you were talking high end capablities. 16 I/O I would go with something like a Micrologix 1100 if choosing AB. Less than $450 with a Ethernet port. Much cheaper than a PC and we haven't even started talking about I/O Don't need an Ethernet Port? Pico for less than $200 and software is free Edited 1 Feb 2006 by TWControls

[kb9ttx 0]

I thought I'd check into what you were saying. From the AB site, I pulled off the price for the Micrologix 1100. (1763-L16AWA, MicroLogix 1100, 16 Pt., $550.00) According to the information about the 1100 on the AB site, one would need RSLogix 500 to program it. (9324-RL0300ENE, RSLogix 500 Standard, $1,167.00) (This is assuming that it is a small company without a lot of automation infrastructure in place.) Anyway, PC based control can be more cost effective for some businesses than others. Further, depending on the architecture, a business might be able to use one of its older servers as the controller. This could make the cost of investment slimmer for some companies. Someday, the PC will be antiquated and some other technology will replace it, as well. Just as the Monks lost their jobs transcribing books to the evils of the printing press, the PLC will be replaced by something. Cheers.

[TimWilborne 108]

I guess the debate will go on One thing I will say is that PCs have become a valuable tool as far as machine diagnostics and viewing data with the new PLCs built in Web Servers. Of course the PCs are still in the office

[TimWilborne 108]

And kb9ttx, if that is the price you are paying for Ab then you need to have a serious talk with your distributor. He's ripping you a new one

[IO_Rack 178]

Before this topic goes off on a tangent, I would add..... 1) He did state he got these prices from AB's web site. So they are probably list prices. 2) Generally long term discounts are given in a confidentiality agreement. I'm not sure about Mr.PLC's policy here but it is probably not a good idea to discuss local distributer's prices.

[TimWilborne 108]

Your right. I've stated my opinion and he stated his. Need to leave it at that. Actually we do have one semi PC controlled machine here (SLC and PC in combination) that has done very well. Probably the biggest problems we have had with it is monitors going out and one hard drive crash. But that one is a sore subject since the 40 MB hard drive cost us a fortune since they have it so you can't copy the program and we had to order it from them with the program on it But we have had to remove 2 others because they were unreliable Edited 1 Feb 2006 by TWControls

[kb9ttx 0]

What options for a "softPLC" do you know about? When I think of a softPLC, I think of a computer with I/O or remote I/O communicating to a PC via OPC. In this kind of arrangement, one can create a custom application in VisualC or something to do tasks. However, when I do an Internet search, I see softPLC's as being less of a PC with I/O to being a dedicated processor made exclusively for control. Such as that shown on "http://www.softplc.com/products.php". This kind of differs from my concept of a softPLC. Further, this kind of softPLC looks more like an actual PLC. Comments?

[GerryM 2]

A Soft PLC to me is PLC done in software regardless of the Hardware. Yes, good point that there are soft PLCs that look like and act like a normal PLC. For the most part these are probably fine used as a PLC, but in many cases why not just use a regular PLC? Once again it depends on the application. I have used several WinPLCs from automationdirect and they work fine as a PLC. The external communication is not the greatest, which is why I switched back to regular PLCs, but any machine they were in has never had problems. A SoftPLC used in a regular PC box I have used with mixed results. I have used Steeplechase and ThinknDo. I have used VB with OPC to a PLC. My favorite of those is VB with OPC to the PLC. I have the least number of problems this way. The application is pump testing, so i always have a PC with a database, its just a matter of how much is in the PC and how much in the PLC. In summary, I think the use of SoftPLCs depends on the application, and the hardware setup used. For industrial automation: Nothing, in my opinion, is more reliable than a PLC for a machine control. The PLC is a 'right out of the box' 'you can depend on it' type of control. Its when you tie in datalogging, networking, etc. that soft PLCs can become more useful. But, many of these features are showing up in PLCs now, and I think that is the way to go in the future. For product design: I think it is very possible to use soft concepts, and design a robust control as good as a regular PLC. It just takes a good design and testing.

[gravitar 3]

Well there's the standard multi-tier discount system that is no secret. There's a price multiplier for "Small User", "Large User", "Small OEM", and "Large OEM", all based on yearly sales volume. Well I should say loosely based on sales volume, If you have one big order but very little else over the year, you can usually persuade your salesman to bump you up a category or two. The only thing that's the least bit confidential are blanket pricing agreements. These only exist between Rockwell and **BIG** customers. Here in Detroit we have a lot of big players so there's quite a few blanket pricing agreements. Even these aren't terribly secretive or confidential though.. Call up an A-B distributor that has an auto plant in town, tell 'em you're with that plant and need pricing on something, and in a few seconds you'll know exactly how much they pay!

[brucechase 1]

gravitar, Let me know where I can get some of them parts. I have some 33MHZ machines that can not use larger than 500MB hard drives. It's the Unix operating systems that limits this. I have resorted to buying flash HD (at $500 each) because I can't find anything that small anymore. I recently purchased 15 old drives from a computer salvage co. and I could not get even 1 to run reliably. Machine downtime is a killer (we need a smiley for pulling out our hair). I know I'm way off topic but I just really want to post something since I haven't in a while.

[gravitar 3]

IDE drives? I've probably got a dozen or more 3.5" IDE HDs of 500 MB or less. Want 'em? Do I need to save atleast one for if I ever get around to loading Linux on a PC? :) I've got a few small SCSI drives as well, but not nearly as many. Is it mainly HDs that you need or other PC parts?

[TERdON 9]

I have no trouble booting my 486DX2 with Linux and an 1 GB drive, although it really doesn't support stuff bigger than 500 MB. Or floppy booting maybe isn't an option in your case? Or is it a propietary, obviously sucky Unix which doesn't support floppies? By the way, I have two small disks too. I would happily exchange my 200 MB one for something more current. . The 50 MB one (which barely has been used) I don't want to sell. Finally, about the price: flash drives really are the way to go in your case, actually. Much more reliable. But it seems you're paying through the nose for them! Here you can buy an IDE-CF-converter for $8. For sure, a 500 MB CF card would be about a tenth of what you're paying? It won't be quite as reliable as a purpose built IDE flash drive, but you can easily exchange it, and anyway, you started with comparing it to ten year old hard drives... The price for an integrated solution still seems pretty high, though. Are you sure you are getting a good deal with your distributor? Here they only need €136 for a flash disk of the same size... And you probably can get even better deals, they were just the first hit on Google with IDE flash disks and pricing.

[Camel 1]

I have never heard of that 500mb limit??? Are you guys sure??? I had Red Hat installed on a laptop with an 80GB hard drive and it worked fine.

[TERdON 9]

There is no such limit in Linux, for sure. It is quite usual with such limits in the BIOS however. One of the ancient ones were at 512 MB (it's the one present in my 486DX2). Most pentium era computers don't have it however. As the problem isn't with Linux, it can be solved by floppy booting (easy), or, possibly, fiddling with the bootloader (not that easy). But all this is under the presumption that it is Linux that's being used. There are other unices than Linux...

[Camel 1]

Good. I started to worry........