Small PLC eval

W

William Sturm

Does anyone have Linux programming software for their PLC?  I can't think of any.  I suspect that very few ask for it too.

Bill Sturm
Abbeytronics LLC

 
K

Ken Emmons Jr.

Speaking of the Click modules... Does anyone happen to know the actual IO scan rates of the things? Sometimes the add on module PLCs use a slow serial protocol that slows your scan down. I didn't know if the Click has any of these limitations.

KEJR
 
W

William Sturm

Serial backplanes are not a bad thing.  Serial data can be more reliable and it doesn't have to be slow.  The PC industry is going this way.  PCI Express, for example, is serial.

Bill Sturm
Abbeytronics LLC

 
C
Not yet, but probably soon. Most of the embedded people are using Linux now and they would be the folks picked to write a new generation of PLC software. My problem is that I can get set up with a complete development system, but then I have to double the cost to buy Windows. I suppose if you can afford $1000 for RSlogix, Windows is a minor drawback. And if you already have Windows of the right flavor, you're good. But, the point of these small PLC packages is low entry cost and it seems kinda bogus that MS should get 50% when you can have a perfectly good OS for free and save 50%. Right now. I don't really have the $100 for Windows, not to mention having to trash a perfectly good reliable system to run it. So I'm watching the rummage sales and freecycle for an "old" PC with XP on it. I figure _someone_ must have bought into the Vista scam and rendered their "old" PC obsolete. W2K would be an option, but it will be much harder to find period hardware to run it on. But, so far, no one has come close to the entry cost for a Click development system, even it I include the Microsoft tax.

Regards
cww
 
C
Automation Direct is scrupulous in that they actually include IO in their scan rating, unlike some vendors. I would have to look if they included modules too or just the built-in. I will do so, since I was headed there this afternoon anyway. Yes, some use a very narrow bus or serial methods between modules, but I seem to recall that Click has a higher pin count connector.

Regards
cww
 
C
Yes, but serial with a 2 core 3 GHz processor and high bandwidth bus
is different from the processors most PLCs are built with. Controlling the impedances and and parasitics gets pretty ugly with lots of connectors.

Regards

cww
 
K

Ken Emmons Jr.

No real problem with serial, but depending on how it is implemented it could be very slow for high IO counts especially. I've seen parallel backplanes that are remarkably slow to scan even when compared to the "single digit MHZ" parallel 8 bit bus backplanes that were popular when I was just a kid. I'm always amazed when something cheap and easy to use in the PLC arena also is blazing fast. The Click could be pretty cool if this is the case. Now if they add callable functions (Function blocks in IEC speak) and libraries it would be really cool.

KEJR
 
C
Here's the info straight from AD tech support:

> Maxing out the IO points on the Click may increase the scan by maybe 1ms.
> The bulk of the scan time is spent solving the ladder program.
That gives maybe 5 ms. total with a full house config and 1k words. And you get 8k which is quite a bit of code for a mini PLC.

Regards

cww
 
C

Curt Wuollet

OK here goes, It's really late but I solved the problem with a Dell GX270 desktop: 2.8Ghz P4 with HT, 512mb RAM, 10Gb hdd(kinda small), Windows XP Professional with the COA and the Re install CD : $49 Plus shipping. The shipping was kinda steep at $33 but this is a little heavier unit. It _should_handle the Click software :^) I used ebay with a search in computers and networking, Desktops, Windows XP Pro, $30 to $80, Buy it Now only. I could have got something easily for $50, but the 2.8ghz P4 with hyper threading will be useful much longer than a 1.7 Ghz Celeron and when I get a job it will make a
Hellacious Linux machine. And I still haven't contributed a nickel to a predatory monopoly.

Regards

cww
 
You said you were going to see if the Click software would work in WINE. Did you have a chance to try that?

As for the 10GB hard drive, 80GB PATA drives for desktops are only about $50 to $60. If the PC has an MS software license sticker on it, you can replace the drive. At this point, that sticker is the most expensive part of the computer. The existing drive should be big enough though, unless there's a lot of junk already installed on it.

Something you might want to do though is to set up a SAMBA network. That will let you put all your reference documents (PDFs, etc.) on the SAMBA server and just access them over the network. That will avoid storing them on the hard drive of the new PC.
 
C

Curt Wuollet

I decided for several reasons to keep the Windows stuff quarantined on a separate environment. This is facilitated by the fact that it is much cheaper to buy Windows on a machine than to buy Windows. And I like where the money goes better that way. I also need a Windows environment to deal with the idiotic HR bots that many companies make you apply through. Some of them don't work with Linux and one even crashed when I tried to import a plaintext resume. I probably can write off that application :^).

When you are applying for a computer job, it doesn't look good if you have a mangled resume, even if it's their fault. It does irritate me when a site wants a Linux expert applying for a Linux job to submit their resume in Word format only. If typing the same information if 10 times a day isn't dumb enough, having them send a paper application in Word format tops things off. Back on topic....

Regards
cww
 
C

Curt Wuollet

Just as a followup, I did try the Click software on Wine or rather Crossover Pro (WINE without the screwing around) I was encouraged when the InstallShield installer ran through without apparent error, but the software won't run on either Fedora 5 or Ubuntu 8. Oh well, the Windows box will be here in a few days.

A really, really interesting note is that since installing Crossover, I've had several malicious redirects try to install various malware on my Linux box. It must provide ports they are scanning for. Fortunately, Linux will not autorun downloads even with crossover installed. I was almost curious enough to see if I could succesfully catch a Windows virus on my Linux box but, instead just deleted the garbage and notified the webmasters of the redirects.

One was for Host Engineering, providers of software and stuff for Automation Direct. I suppose when the Windows box arrives, it will be compromised almost immediately. At least it won't have anything important on it. I'm removing crossover, life is much better without all the Windows "features". I hope the Windows box runs long enough to do the jobs thing.

Regards
cww
 
Getting the Click software to work with WINE without putting a lot of work into it was probably a long shot anyway. There are often a lot of special settings that have to be figured out to get a new program working with WINE, and some programs simply won't work at all. The main application for WINE seems to be for running games, and those doesn't interest me so I only used it once, and then only for a short period of time. Other than games, there is very little software meant for MS Windows that people using Linux are interested in anyway.

However, a while ago I did get the Direct Soft (for the Koyo DL PLCs) software working on ReactOS under QEMU emulation. This was just to try to see if it could be done, so I didn't do anything practical with it. It was rather flaky, so I couldn't recommend it as a solution (the ReactOS people themselves say it isn't ready for normal use yet). I have the latest version of ReactOS installed in a VM but it has some problems with mapping virtual drives (this is a ReactOS problem, not a QEMU problem) so I wasn't able to see if the Click software would run on this.

As for viruses delivered through web sites, there is a lot of that going on now. They get delivered through ad servers or else the web site gets hacked (usually through simply guessing a weak password) and extra hidden links inserted into the web pages. There's really no such thing as "safe" and "unsafe" web sites any more. That's why if you are using a PC with MS Windows for something like an HMI or SCADA work station, it shouldn't be used to surf the Internet.

It's interesting that installing WINE appears to make the malware installer think that it is talking to a computer running MS Windows. The open ports idea sounds plausible. You might want to check though if Crossover did something "helpful" like change the user agent string in your web browser to say that it was MS IE.

If I had to speculate with why a virus down loader would go through the extra effort to actively avoid a computer with Linux, I would guess that it is trying to hide from the web site administrators (they surf to the site with their Linux PC, and don't see any problems). I've heard of this sort of thing, but I can't recall where.
 
C

Curt Wuollet

Hi Michael,

M Griffin: > Getting the Click software to work with WINE without putting a lot of work into it was probably a long shot anyway. There are often a lot of special settings that have to be figured out to get a new program working with WINE, and some programs simply won't work at all. The main application for WINE seems to be for running games, and those doesn't interest me so I only used it once, and then only for a short period of time. Other than games, there is very little software meant for MS Windows that people using Linux are interested in anyway. <

CWW: There isn't any that I'm interested in running. It's only the present dire situation that has me dipping into the cesspool of viruses and such.

M Griffin: > However, a while ago I did get the Direct Soft (for the Koyo DL PLCs) software working on ReactOS under QEMU emulation. This was just to try to see if it could be done, so I didn't do anything practical with it. It was rather flaky, so I couldn't recommend it as a solution (the ReactOS people themselves say it isn't ready for normal use yet). I have the latest version of ReactOS installed in a VM but it has some problems with mapping virtual drives (this is a ReactOS problem, not a QEMU problem) so I wasn't able to see if the Click software would run on this.

As for viruses delivered through web sites, there is a lot of that going on now. They get delivered through ad servers or else the web site gets hacked (usually through simply guessing a weak password) and extra hidden links inserted into the web pages. There's really no such thing as "safe" and "unsafe" web sites any more. That's why if you are using a PC with MS Windows for something like an HMI or SCADA work station, it shouldn't be used to surf the Internet. <

CWW: IMHO it shouldn't be used for anything more crucial than an egg timer anyway. That supposedly responsible people like banks and the government _require_ you use the _highest_ risk alternative indicates there is something rotten in Denmark. Much like the insistence in automation that you use the least reliable alternative.

M Griffin: > It's interesting that installing WINE appears to make the malware installer think that it is talking to a computer running MS Windows. The open ports idea sounds plausible. You might want to check though if Crossover did something "helpful" like change the user agent string in your web browser to say that it was MS IE. <

CWW: It's gone now, or I would. It was hilarious that they would zero in on anything that even smelled like Windows.

M Griffin: > If I had to speculate with why a virus down loader would go through the extra effort to actively avoid a computer with Linux, I would guess that it is trying to hide from the web site administrators (they surf to the site with their Linux PC, and don't see any problems). I've heard of this sort of thing, but I can't recall where. >

CWW: This is a serious problem though, I haven't played the AV game for years and unless I devote time to get up to speed, my shiny new Windows box will be compromised in minutes with a high speed connection. I hope there is something free that will give me a fighting chance. Even if I put it behind a Linux firewall, the things that Windows uses to interact with job sites, etc. will still make it vulnerable.

I have downloaded G4L (Gh*st for Linux) and will make a disk image backup before exposing it to the web so when I need to blow it away and reload, I won't spend days chasing drivers and the like. I just don't like the idea of keeping my personal data, (and job apps get pretty personal) on an easily compromised machine. Many companies insist on all the information needed for identity theft. I wish they had some sensitivity to how bad the present security situation is. Many HR bots don't even use _weak_ encryption.

Regards
cww
 
C

Curt Wuollet

A follow up. Got the "new" machine. It's as advertised, had to reload WXP twice to get it to run with all the needed drivers and it took all day. But that's not very interesting. Does run the Click stuff just fine.

What I think should be interesting for automation folks is the G4L I used to back it up so in a week or two when it's compromised, I can just blow it away and start fresh. *nix guys have used dd and friends for decades to make exact copies of partitions and whole disks for backup. Ghost didn't invent anything.

What G4L does is makes that easy for anyone to do for free. I have a CD that I can put in a Windows machine and boot and it backs the entire 10Gb disk image across the network in 6.5 minutes to my Linux box (or any ftp server) it compresses on the fly so the image was less that 1.5Gb. Retrieval is pretty much the same. It'll do partitions and clone disks as well.

I know there are other ways to do this, but G4L has some big advantages. It's immune to boot sector viruses. It carries it's own OS which is also GPL, no license hassles. And you can legally stick a copy in each box for emergencies. You have the source and scripting so you can eliminate answering any questions by plugging in your defaults. I can recall many instances where I would have really liked to back up before I make changes, if it was fast and easy. Or when a hdd fails and I need to replace it, I can be up again in minutes, not hours. Almost any place has a ftp server and off-site is just as easy. And of course, it doesn't belong to IS/IT so it will be available when you need it. Check it out on SourceForge.

Regards
cww
 
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