RS232 to Ethernet (programmable)


Thread Starter

Harry Friemann

We currently have a network in our plant, which connects Philips PC20 plc's. Each PLC has a CI (communication interface) card, which supports RS232. The messages send from/to a PLC are now going through a LOCAN network, once made by CFT Philips. This network is absolete and I am looking for a solution in renewing this. I was think of replacing the LOCAN boxes at each PLC site with a new box, which convert RS232 to TCP/IP Ethernet and vice versa. But the box should look inot the message whcih has a kind of address in the second byte. This adress should be converted to an ip-adres and the message should be send there.
Can anyone suggest such a device. Most of the devices i have seen only convert rs232 to tcp/tip and cannot be dynamically address messages.

Sincerely yours,
Harry Friemann
I think you would be better off finding an RS232 to RS485 converter. Since the PLCs or other devices, I assume, aready respond to the string and it's embedded address that would be a 'no-brainer'.
If you want to go IP then you would need some programability in the 232/IP converter.
We use a converter called COBOX by Lantronix. They may have something for you.


Juan De los Santos Naumov

Hello Harry,
Have you tried with lantronix ( they have some interesting tcp/ip device servers.

If you use at your central location one of these "boxes" broadcasting messages with the "real data" encapsulated into the tcp frame and you connect at the other end similar boxes configured to initiate transmission only to the central IP address the following will happen:

the broadcast message will be delivered to all the "remote" nodes but only node that receive the correct address in the second byte will answer the

And, the replay will be addressed only to the master because you can configure the Lantronix devices to initiate session to different IP address.

Please check for the MSS-100 or UDS-10

I hope this help you.

Juan De los Santos Naumov [email protected]
Division Manager
Industrial Control Division
(598) 2 902 5785 (TEL)
(598) 2 902 9151 (FAX)
Few lines of Python on a headless Linux box. Stick the script name in innitab so it always runs and relaunches after exceptions. You do not need to write the disk so mount it read only and set the power down parameters on the drive so that it only gets used for booting.

I know people will make a lot of comments about such an approach, but I have been sticking basic linux boxen such as this in industrial environments scince 1995, and they just run with zero intervention.

BTW, some time ago I stuck a Linux box where there would be nobody actually using it or keeping an eye on it, it just did some net
services. As the network had an internet gateway a stuck a script in the crontab to send me the tail of the syslog every day so I could see
if it was going haywire. That site no longer exits, the company was taken over by a multinational and divisions split up and sent all
over the place. The building stands empty, and I have no idea where that computer ended up.

But I still receive the emails and I have never seen any irregularities:)

As you can see, the message is being sent direct to my mail ISP from boxes own SMTP daemon:

Received: by (mbox irwin)
(with Cubic Circle's cucipop (v1.31 1998/05/13) Thu Oct 26 18:01:05 2000)
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Date: Thu, 26 Oct 2000 08:08:02 +0200
From: root <[email protected]>
Message-Id: <[email protected]>
To: [email protected]
Subject: Hello
X-Mozilla-Status: 8001
X-Mozilla-Status2: 00000000
X-UIDL: ae0e63977a070000

Oct 26 06:45:00 server /USR/SBIN/CRON[19629]: (root) CMD ( test -x
/usr/lib/cron/run-crons && /usr/lib/cron/run-crons )
Oct 26 07:00:00 server /USR/SBIN/CRON[19651]: (root) CMD ( test -x
/usr/lib/cron/run-crons && /usr/lib/cron/run-crons )
Oct 26 07:00:00 server /USR/SBIN/CRON[19652]: (root) CMD ( test -x
/usr/sbin/faxqclean && /usr/sbin/faxqclean)
Oct 26 07:15:00 server /USR/SBIN/CRON[19672]: (root) CMD ( test -x
/usr/lib/cron/run-crons && /usr/lib/cron/run-crons )
Oct 26 07:30:00 server /USR/SBIN/CRON[19691]: (root) CMD ( test -x
/usr/lib/cron/run-crons && /usr/lib/cron/run-crons )
Oct 26 07:42:45 server -- MARK --
Oct 26 07:45:00 server /USR/SBIN/CRON[19711]: (root) CMD ( test -x
/usr/lib/cron/run-crons && /usr/lib/cron/run-crons )
Oct 26 08:00:00 server /USR/SBIN/CRON[19733]: (root) CMD ( test -x
/usr/lib/cron/run-crons && /usr/lib/cron/run-crons )
Oct 26 08:00:00 server /USR/SBIN/CRON[19734]: (root) CMD ( test -x
/usr/sbin/faxqclean && /usr/sbin/faxqclean)
Oct 26 08:08:00 server /USR/SBIN/CRON[19753]: (root) CMD ( /etc/
Hi Juan De los Santos Naumov,
I wanna know if you know how to write device drivers to be embedded into these device servers.
Because I am at a loss on how to write a device driver that reads a mitsubishi fx net plc nad auto sends a email when values have reached their critical state.
If you have an answer,can you contact me at "[email protected]": mailto:[email protected]

Your help will be appreciated

Thanks and Regards,
Xu Weijie
from Singapore