Linux as Ethernet to serial bridge

Hello,

I'm looking for a solution to bridge an ethernet connection
to a serial connection.
I have found a hardware solution, but haven't bought it yet.
I thought (hoped) there might be a Linux solution to the
problem, but I can't figure it out myselft.

I need to translate exactly what comes in on an ethernet to
go out to a serial port and reversed. The purpose is to
transmitt NC code from a PC to a NC machine over a long
distance.

Maybe it is not possible due to speed differences and buffer
problems but I thought I could ask.
Maybe this only requires a simple script by those who know
how to write them :-)

regards
Bjorn

On 2003-12-09, Bjorn <(E-Mail Removed)> wrote:

> I need to translate exactly what comes in on an ethernet to go
> out to a serial port and reversed. The purpose is to transmitt
> NC code from a PC to a NC machine over a long distance.
>
> Maybe it is not possible due to speed differences and buffer
> problems but I thought I could ask. Maybe this only requires a
> simple script by those who know how to write them :-)

netcat ought to be able to do what you want.

--
Grant Edwards grante Yow! Is this where people
at are HOT and NICE and they
visi.com give you TOAST for FREE??

hope you don't have alot of incoming ethernet traffic.

On Tue, 09 Dec 2003 14:39:30 GMT, "Bjorn" <(E-Mail Removed)> wrote:

> I'm looking for a solution to bridge an ethernet connection
> to a serial connection.

http://linux.opennet.ru/base/cisco/eth_bridge.txt.html

--
/// Michael J. Tobler: motorcyclist, surfer, skydiver, \\\
\\\ and author: "Inside Linux", "C++ HowTo", "C++ Unleashed" ///
When a fellow says, "It ain't the money but the principle
of the thing," it's the money. - Kim Hubbard

Bjorn wrote:

> The purpose is to
> transmitt NC code from a PC to a NC machine over a long
> distance.

Define "long distance".

--

Fundamentalism is fundamentally wrong.

To reply to this message, replace everything to the left of "@" with
james.knott.

Thank you for your link, but even if my russian is a bit rusty I think
this is how to configure a CISCO router to bridge from Ethernet to
Serial. Isnt' that right?
My idea was to use a low spec PC with linux to do the bridging.

/Bjorn

"mjt" <mjtobler@removethis_consultant.com> skrev i meddelandet
news:Q7nBb.7390$(E-Mail Removed) ink.net...
> On Tue, 09 Dec 2003 14:39:30 GMT, "Bjorn" <(E-Mail Removed)> wrote:
>
> > I'm looking for a solution to bridge an ethernet connection
> > to a serial connection.
>
> http://linux.opennet.ru/base/cisco/eth_bridge.txt.html
>
> --
> /// Michael J. Tobler: motorcyclist, surfer, skydiver, \\\
> \\\ and author: "Inside Linux", "C++ HowTo", "C++ Unleashed" ///
> When a fellow says, "It ain't the money but the principle
> of the thing," it's the money. - Kim Hubbard

With "NC machine" I mean a CNC controlled milling machine
for example. We have other milling machines that have a built in
ethernet card, but one of the machines isn't possible to upgrade.
My idea was to be able to use the same communication procedure
for all machines instead of two different.

In a Linux box I want something like
http://serial-ethernet.com/serial-et...-ethernet.html
Looking at the lower part of that homepage you will see a CNC
application example.

/Bjorn

"Floyd Davidson" <(E-Mail Removed)> skrev i meddelandet
news:(E-Mail Removed)...
> "Bjorn" <(E-Mail Removed)> wrote:
> >Well, long distance... it's about 35m but the enviroment contains
> >lots of other noisy machinery that might disturb the signal.
> >I used a normal serial cable (shorter, 20m) before and it worked,
> >but speed wasn't so good.
> >So I want to put a Linux PC close to my NC machine with only
> >a short serial cable between them and hopefully get up to full
> >serial speed, 115Kbps.
>
> I'm not sure I've figured out yet what is being done. What is
> an "NC machine"? Does this machine *only* have serial port
> capability? And is 115Kbps the highest rate that it can work at?
>
> If that does describe what you have, then yes putting a Linux
> box next to it will allow you to run the RS-232 link at 115Kbps.
> If your environment is really obnoxious you can even use
> shielded cable if you keep the length very short. But *do* use
> cable intended for RS-232 (e.g., do *not* use twisted pair like
> CAT 5). If the cable can be less than 2m, even with shielding
> you'll be able to use 115Kbps.
>
> --
> Floyd L. Davidson <http://web.newsguy.com/floyd_davidson>
> Ukpeagvik (Barrow, Alaska) (E-Mail Removed)

"Bjorn" <(E-Mail Removed)> wrote:
>With "NC machine" I mean a CNC controlled milling machine
>for example. We have other milling machines that have a built in
>ethernet card, but one of the machines isn't possible to upgrade.
>My idea was to be able to use the same communication procedure
>for all machines instead of two different.

Ah. The significant point is that it can't use an ethernet card.

>In a Linux box I want something like
>http://serial-ethernet.com/serial-et...-ethernet.html
>Looking at the lower part of that homepage you will see a CNC
>application example.

I think you have a sound approach. Just use a computer with a
case that can be sealed up fairly tight electrically, and get
it as close to the serial port on the milling machine as you can.
With it that short, I'd go for shielded cable to start with.

The significance of cable intended for RS-232 is that it will
have thicker insulation on the individual wires, to keep them
farther appart from each other, thus there will be less
capacitive coupling between them. Don't use a cable meant for
something else.

Shielding the cable reduces the length/speed that you can use,
but improves the noise immunity.

At just a few feet, you should not have a problem at 115Kbps.

>"Floyd Davidson" <(E-Mail Removed)> skrev i meddelandet
>news:(E-Mail Removed)...
>> "Bjorn" <(E-Mail Removed)> wrote:
>> >Well, long distance... it's about 35m but the enviroment contains
>> >lots of other noisy machinery that might disturb the signal.
>> >I used a normal serial cable (shorter, 20m) before and it worked,
>> >but speed wasn't so good.
>> >So I want to put a Linux PC close to my NC machine with only
>> >a short serial cable between them and hopefully get up to full
>> >serial speed, 115Kbps.
>>
>> I'm not sure I've figured out yet what is being done. What is
>> an "NC machine"? Does this machine *only* have serial port
>> capability? And is 115Kbps the highest rate that it can work at?
>>
>> If that does describe what you have, then yes putting a Linux
>> box next to it will allow you to run the RS-232 link at 115Kbps.
>> If your environment is really obnoxious you can even use
>> shielded cable if you keep the length very short. But *do* use
>> cable intended for RS-232 (e.g., do *not* use twisted pair like
>> CAT 5). If the cable can be less than 2m, even with shielding
>> you'll be able to use 115Kbps.

--
Floyd L. Davidson <http://web.newsguy.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) (E-Mail Removed)

Floyd Davidson wrote:

> I think you have a sound approach. Just use a computer with a
> case that can be sealed up fairly tight electrically, and get
> it as close to the serial port on the milling machine as you can.
> With it that short, I'd go for shielded cable to start with.
>
> The significance of cable intended for RS-232 is that it will
> have thicker insulation on the individual wires, to keep them
> farther appart from each other, thus there will be less
> capacitive coupling between them. Don't use a cable meant for
> something else.
>
> Shielding the cable reduces the length/speed that you can use,
> but improves the noise immunity.
>

For use over long distances or in a noisy environment, RS-442 or RS-485 are
far superior, because they use balanced pairs. Adapters are available to
convert to RS-232.

--

Fundamentalism is fundamentally wrong.

To reply to this message, replace everything to the left of "@" with
james.knott.

"Bjorn" <(E-Mail Removed)> wrote, variously:
|
| With "NC machine" I mean a CNC controlled milling machine,
| for example. We have other milling machines that have a built in
| Ethernet card, but one of the machines isn't possible to upgrade.
| ...
| In a Linux box I want something like
| http://serial-ethernet.com/serial-et...-ethernet.html

| > So I want to put a Linux PC close to my NC machine with only
| > a short serial cable between them and hopefully get up to full
| > serial speed, 115kbps.
| > ...Well, long distance... it's about 35m but the environment contains
| > lots of other noisy machinery that might disturb the signal....


Using a general-purpose machine running a general-purpose operating
system just to tunnel an asynchronous serial connection over
Ethernet/TCP/IP/Telnet is a lot of overhead.

While the "serial-ethernet" devices from "ipcas GmBH" (at the above
URL) appear, at first glance, to be uncomfortably Windows-centric to
a Linux guy, another vendor has a similar idea.

Lantronix makes several simple, little, plug-and-go products.
Several of them are intended precisely for industrial automation:

http://www.lantronix.com/products/ds/index.html

One of them can use a fiber-optic Ethernet medium for noise immunity:

http://www.lantronix.com/products/ds...iap/index.html

On the other hand, some potentially useful Linux-based software
is visible here:

http://www.linuxlots.com/~termpkg/

--
H.O.