Wireless Ethernet in industry

MrQ · Mar 25, 2010

Hello,

What are your experiences in using Wireless Ethernet in the industry?

I am looking at a system where I have one cabinet with a PLC + a display that both communicates via Eth. Then there is one moving unit with two VFDs and remote I/O that can communicate via Ethernet.

The distance will me max 150 meters and clear sight.

Has anyone used the Rugged Wireless LAN Ethernet Port Adapter - RWEPA from Connect blue?
http://www.connectblue.se/products/...-housings/rugged-ethernet-port-adapter-rwepa/

It looks good at least on the paper...

zankorel · Mar 25, 2010

MrQ said:
Hello,

What are your experiences in using Wireless Ethernet in the industry?

I am looking at a system where I have one cabinet with a PLC + a display that both communicates via Eth. Then there is one moving unit with two VFDs and remote I/O that can communicate via Ethernet.

The distance will me max 150 meters and clear sight.

Has anyone used the Rugged Wireless LAN Ethernet Port Adapter - RWEPA from Connect blue?
http://www.connectblue.se/products/...-housings/rugged-ethernet-port-adapter-rwepa/

It looks good at least on the paper...

I would be hesitant at using Wireless Ethernet to do any control over the RI/O, as long as it is monitoring only it would be ok.

I use wireless quite a lot for HMI and inter PLC comms and it is pretty good. Just make sure you are really careful if you use any mesh features as it can really screw your network up if you dont know what you are doing (and sometime even when you do if you have a complex network)

MrQ · Mar 26, 2010

zankorel said:
I would be hesitant at using Wireless Ethernet to do any control over the RI/O, as long as it is monitoring only it would be ok.
quote]

How come? Due to interference problems or other reasons? If I loose connection to the RIO they will loose signal and this is the safe state for the system. I will get a signal in the PLC and can turn of the automatic state of the system.

Of course if there is some reason that I believe I will loose connection all the time it is no good.

Johnster · Mar 29, 2010

I think that most ethernet-wise people would shy away from using it for control...especially wireless. You already called out a few of the reasons

1) Interference - you don't want electrical noise getting into your packets and starting/stopping machinery

2) Deleted =)

3) Latency - std Ethernet is not 'deterministic' meaning, that data is not communicated on any kind of schedule. Google CSMA/CD for a better explanation that says "sometimes, your data might sit and wait to be transmitted, and sometimes it wont.

4) security - all computer systems/security methods are hackable. having a wireless node greatly expands the amount of real estate that would need to be guarded/protected to enact any kind of physical security vs. intrusion. The security/operations ramifications of this are very far reaching in my world (power production)

The reasons above are enough for me to never control over wireless ethernet, and make me very hesitant to even monitor things wirelessly.

-John

JesperMP · Mar 29, 2010

For a system that is controlled via wireless ethernet, I would go for Profinet, and wifi equipment that is certified for Profinet. I know of some projects that use these with success. I would not "invent a system on my own". Siemens has a complete suite of products for this, but count on that they are "not cheap". You get what you pay for.

I know there are 3rd party suppliers of wifi for Ethernet/IP. Not sure if Rockwell has their own line of equipment.

dondon_alba · Mar 29, 2010

Hi,

Try RadioLinx Frequency Hopping (RLX-FH) radios from “Prosoft Technology”. We have this in our plant for five years for our giant overhead cranes by NKM NOELL and it’s been working trouble free. If you are interested check their website www.prosoft-technology.com

Don

Stephen Luft · Mar 29, 2010

Mr. Q,

You have a manufacturer in your own back yard...Westermo.

Their RM240 should be sufficient for your application.

Here is a link to that information and data sheets:

http://www.eternity-sales.com/Westermo/Industrialwireless.htm

Hope this helps.

God Bless,

rocket · Mar 29, 2010

I use quite a bit of Ethernet both over wireless and wired networks Siemens and AB. But generally I would not recommend for Remote IO - only for monitoring and basic control (HMI, Scada interface etc). Well, it all depends on the process. I prefer a local PLC at the process that is programmed with correct default action in the event of comms loss. I would only use Wireless Ethernet in Remote IO for applications with no safety or process risks. No matter what who says, wireless is never trouble-free. You might get it close to 100% reliable but "close" is always the operative word...

mordred · Mar 29, 2010

I concur on remote I/O especially critical I/O points monitoring is one thing but I've encountered too many problems with wireless regardless of how much is spent on it to rely on wireless for critical I/O. Your better off with something like devicenet or profibus

toma743 · Mar 29, 2010

You could try a DIN mount wifi client like http://www.plctalk.net/qanda/showthread.php?t=54189 for the mobile end. For the fixed end there is this: http://www.icpdas-usa.com/nwh660.html . There is encription, which I consider to be very important.

Wireless Ethernet in industry

MrQ

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