Remote Access to a Control Logix System

[GregPLC]

Mike, to possibly give an answer to your question, "why would you be afraid to modify the IP or code? If you're in a plant such as ours, where each system is validated changing code can have very bad results.

It may be that if he changes one instruction in the code, or even modify's the TCP/IP settings of the processor, they would have to revalidate the system. We are under FDA and USDA, so I'm in that sort of environment.....it's the only thing I can come up with. My wild guess is he's pharma or food, like me


Greg

 

[GregPLC]

Jeff, to answer your question, he stated they have the same IP addresses......that would not work on the same network (through the switch).


Greg

 

[elevmike]

Greg,

With all due respect, I really think that might be a stretch. I have read and re-read gareth's posts, and they seem somewhat conflicting. His reasoning for not wanting to change the existing IP addresses, (which appear the be the default address), seem more due to some issue with the relationship between the OEM and the user; which gareth also stated did not exist anyway.

So admitting that I'm not an AB man, I would 1st presume that there is NO current reference to the IP address in the current code. This presumption is based on the other presumption that the current IP addresses are currently the factory default. Furhtermore, I would further presume that changing the IP address is not an issue of altering the code, but altering the configuration (two different things). Authough one may be able to alter this configuration paramater via the code, I would also presume that it could be also altered via a configuration manager setup. Again "presuming" that I am correct..then changing the IP addresses from factory default is a non-issue..

I will admit I'm doing a lot of presuming here but I dont see anybody correcting my possably presumptious statements...

In any event:
1. The stated reason for not changing the code or configuration was due to the fear of jeperdizing the relationship with the OEM.
2. It was also stated by gareth that the OEM relationship has ceised to exist, and thus the OEM will not provide support.

So what's the problem????

 

[GregPLC]

Like I said, it was the only explanation I could come up with for his reasoning, regardless of which industry this application is in. From my point of view, it's not a stretch, I come up against code change/validation issues all the time. From his application's point of view, maybe this is on a crusher or grinder where there isn't any regulation for code change.

Greg

 

[jdbrandt]

a MEDIA switch, that's the ticket

OK, lets make this easy.

A dial-in LAN-modem, that's the easy part.

One of the ports on the LAN modem will go to a
MEDIA switch (not a 'switch-as-in-an-intelligent-hub type switch).
The other side of the media switch will fan out to the devices.

When the locals want support for device 'X', they turn the
media switch to position 'X', thereby connecting the
LAN modem to the proper physical device.

Support dials in.

Done.

 

[gareth.cantrill]

Thanks to all those of you who replied to my post.

I realise that the post was possibly not the best to understand.

JDBrandt, thanks for your reply. I didnt view all of the posts over the last few days.

However, I think I was maybe over complicating what I was attempting to achieve. As it happens JDBrandt came up with a similar solution as the one I have tested today.

I connected my AB 9300-RADES Modem to a Hirschmann switch, which then linked into a ethernet card which I gave an individual IP address to. The plan now is to put an ethernet card onto each machine. However now I have read JDBrandt's reply I think I should now consider the switch technique he explains. Thus savings me around £2,600.

Thanks again to all. The subject seems to have generated some interest, and I hope it may have helped some of you guys.

Cheers.