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Remotely programming PLCs. 4

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itsmoked

itsmoked

Electrical
Feb 18, 2005
19,114
I'm facing a project where there will be 3 PLCs on a moving platform that moves about the USA. Invariably there will need to be changes to their code. I want to be able to do that remotely. I'm looking for solutions in any form. That is it could be something you buy that will mimic a local programming computer or a fully enabled PLC that has the native functionality. This is going to be a wireless situation, of course.

I'd prefer to use Automation Direct's CLICK series as they have the biggest bang for the buck and I'm very familiar with them but they provide no alternative programming methods as needed, you just plug a programming computer into them via RS232. (Except since I last used one they've added an Ethernet port that you can program thru which might make this a little easier.)

I'm open to any suggestions or brain storming, what have you got?!

Keith Cress
kcress -
 
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Why not just something like a MiFi hooked up to a local LAN. Lots of security needed, but you could basically connect to the Internet and communicate with the PLCs. Or, similarly, a satellite internet approach: The satellite claims to be in geosync, so it's ostensibly available anywhere in the US, might be somewhat better than Verizon. Are the systems constantly on the move? Are they going to be in poor cell coverage areas?

TTFN
I can do absolutely anything. I'm an expert!
homework forum: //faq731-376 forum1529
 
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Hi IR,
MiFi or something similar sounds like a possible solution since they serve up about 10 IP addresses typically.

Some constraints that help the issue is that this would only be done when a human is present at the PLC(s) location as random programming changes could be disastrous. This is because typically PLCs are taken out of RUN and re-initialize when put back into RUN which could upset the apple cart if done at just the wrong time. It would only be done with someone around, which means likely security would be pretty easy as I can have someone need to do something to actually allow a programming change. Something like plug in a cable or take a selector switch out of 'none' and set it to 'PLC2'.

This also means the re-programmings can take place at convenient times and places, i.e. when in a solid reception area and while the system is NOT in geographical motion. So satellite links are probably not a necessity though that one you linked is pretty dang cost competitive!

Keith Cress
kcress -
 
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If you want to roll your own, there are boards that could do that:
tutorial:
But, That's a lot of work, I think. But, there must be code available on the web for this sort of thing. Almost all new products come with a web interface and reprogramming functionality, like the cable modem I'm using now, as well as my security cameras.

TTFN
I can do absolutely anything. I'm an expert!
homework forum: //faq731-376 forum1529
 
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Hadn't thought of that. I like the SIM card angle but I'm kinda concerned by the rumors of everyone dumping GSM stuff real-soon-now. Maybe I have that wrong?

Keith Cress
kcress -
 
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I went thru something similar a couple of years ago but solution was not very elegant, I just provided a cheap laptop with the PLC software (Click software has a free version, right?) and had LogMeIn on the laptop. Required someone local to turn on the laptop and plug it in but from there I had ability to rework the program and had a set of eyes on site to make sure everything was ok.

Not very sexy but worked ok for me, and customer was ok with having the laptop with the programming software on a "programming tool".

MikeL.
 
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Hi MikeL; That's what they had before and it worked.. adequately.. At least until it walked away. :/


IR, et.al.

I kinda want to up the game a little. I'm now trying to improve things a bit more than just programming. It would be really sweet to be able to have anyone with the credentials to log in and see live data too. These are private rail cars by the way. So it would be nice to log in to see the actual position of the car(s); did they get properly transfered? The speed. The consumables stores, water and diesel. The waste tankage remaining. The temperatures inside and out. What power source is on-line; HEP, generator, shore. It might be nice to have a steerable web camera for security purposes.

So seeing those dirt cheap MiFis on epay this is looking more approachable all the time. I'd still want some manual security for the programming function.

Keith Cress
kcress -
 
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That would suggest some sort of webpage-based UI. IF the PLC has access to that much of the vehicle, security and zero-day issues are possibly going to be dominant.

TTFN
I can do absolutely anything. I'm an expert!
homework forum: //faq731-376 forum1529
 
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It occurred to me on the way to work that our enterprise system might a reasonable prototype for connecting to the PLC. We have:
> External VPN access only, which is ostensibly more secure than SSL
> 2-factor access (password and cellphone) for any access, including the VPN itself, and the web interface to Outlook.
> Internal network with internally hosted webpages for access to timecards, etc.

TTFN
I can do absolutely anything. I'm an expert!
homework forum: //faq731-376 forum1529
 
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You can do that very easily with any Rockwell Logix platform PACs, ie CompactLogix or ControlLogix and an Ethernet I/P port, which are virtually all new ones now. All you would need is an IP address at the destination and Studio5000 at your end. That's essentiall how all programming is done now for that platform.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington
 
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Jeff; I can't bring myself to consider anything Rockwell.. For starters as I was looking up Studio5000 at the car-dealer-ship-like Rockwell site it brought down my browser toasting 35 minutes of response to IR.
URL]


Secondly I can't find any prices and I realized the whole scene is going to abstract-off to finding an account person which will result in having to work through the whole "we're out of that module" circular quoting-hell-torture. They should stop with the deep ensnarement methods and come forward into, at least, the 20th century with their sales network. [/rant]

IR(greatly amended).
Thanks for the multi-factor link.
A data webpage served by a local wall mounted mini-PC serving out thru a VPN is a great candidate.
I hadn't considered an Outlook based data collection.

Keith Cress
kcress -
 
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Rockwell isn't the only platform that can support such things, Wago probably can (although CoDeSys 2.3 is showing its age), Omron likely can, GE Fanuc as well.

I must admit I'd prefer not to use Rockwell stuff either if I can avoid it, the whole licencing thing for their programming software is much more painful than other platforms.

All the stuff about security of PLCs as network devices is critical if the intention is to provide a remote ethernet connection for programming, most of the platforms don't have good end point security, and thus rely on people not getting access to the network as a restriction means. Wago runs different user accounts on their PLCs as a security means, but there are some vulnerabilities in some of their (older, I think) units that won't get fixed either.
 
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There's nothing to stop you from using the Click units with an ethernet to serial converter and / or a 4G cellular device with a serial port on it, then you would use the relevant programming software to program it at your end (almost) like you're standing in front of it.

A former employer of mine used to use dialup PSTN connections for all their PLCs and RTUs, with the caveat that to program the PLC, an operator needed to be present to change the serial cable over. I transitioned a number of sites over to direct ethernet, although the wider security constraints were also handled by my employer's network communications department, they had their own VPNs set up, so I didn't need to worry about that aspect.

There are a number of manufacturers now that offer their own supported VPN for their controllers (Comap for generators is one), which takes away a lot of the setup issues, but isn't really helpful unless you can use one of their products directly for your application.
 
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Hi Freddy;
VPN is sounding like maybe the best solution so far. I found this site:
[URL unfurl="true"]http://www.zeroshell.org[/url]

Which has this FAQ page:
[URL unfurl="true"]http://www.zeroshell.org/faq/vpn/[/url]
That seems to describe the perfect setup of essentially tying two LANs together across the internet (VPN LAN-to-LAN). I should then be able to sit here at my LAN and link to the rail car's LAN.

I'm still trying to figure out the niggling details, like how does my end of the VPN actually find the train end as my end is internet connected thru a dynamic IP address and the train end is going to definitely be changing its IP address as it moves about the country.

BTW: Freddy, the CLICKs now come with an Ethernet port so no serial adapters needed.


Hi controlsdude; Can't resist torturing me with archaic "channel distributors" sold products huh?
URL]

The only thing they have that is applicable sounds like a pretty good solution:
Industrial-Cellular-Gateway-ICX35

Now all I have to do is find the distributor, call them, learn how they didn't know they sell the product, and that they'll have to find out availability and cost and get back to me... sigh.

Keith Cress
kcress -
 
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Sierra Wireless make a cellular modem, it's marketed in the US by Prosoft, I looked into it for a similar project.

I asked the local vendor to prove it to me, I was able to make changes in a remote PLC hundreds of miles away. They even had a webcam hooked onto the local network. I could see the trees outside the window waving in the breeze.

I pointed out that it's one thing to get the local IT guy to let you hook on to his network and another to communicate through a PABX, the cell modem bypassed all that.

Unfortunately the project got cancelled before I was able to implement it, one day.
 
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