Re: Industrial PC (Sealed) -- Linux

[Jeff Licquia <jeff@licquia.org>]

ricky@learnautomation.com wrote:
> Now, many companies are looking out over a sea of IP addresses, and their
> maintenance personel can't figure out what's what!  Ethernet IP devices
> have the ability to use hostnames, but a DNS Server must reside on the
> Ethernet/IP network.  This network must be isolated from a TCP/IP nework,
> because TCP/IP packets are not deterministic.  This means that each
> machine on a plant floor has it's own isolated Ethernet network for
> controlling devices, and a separate ethernet module that reports
> statistics to the plant server over the TCP/IP network.

I'm not familiar with "Ethernet/IP", but maybe I can still be of some use.

Way back in the early days of the Internet, hostname lookups were done 
with a hosts file that was centrally edited and downloaded over FTP. 
Obviously, that isn't done anymore, but every OS I've ever run into that 
supports TCP/IP at all still supports them.  It's considered an IP 
thing, so if Ethernet/IP still uses IPv4 in any recognizeable form, 
there's a good chance it's still supported.

I assume that techs need to do the lookups on some kind of "real" 
computer that is either Windows or Unix-like.  If so, you might try 
creating a hosts file for each Ethernet/IP network, and distributing 
them where it makes sense.

If the techs use a single machine for diagnostics, which they plug into 
the Ethernet/IP network they need to, then there could be different 
configs per machine.  You could deal with that a few ways:

  - If you have the luxury of renumbering the Ethernet/IP networks, or 
had the foresight to ensure that the IP addresses were unique 
plant-wide, you can write a single grand global hosts file that covers 
the entire plant.

  - If numbers are shared between isolated networks, you could have a 
series of hosts files.  I'm sure you have an identifier of some kind for 
each machine with its own Ethernet/IP network; use those to identify the 
hosts file.  Then, just copy the hosts file for the machine you're 
working on to the canonical hosts file.

Hope this helps.

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