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Serial Terminal on a LINUX box

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Ok first things first, before i go on we have to be sure that you got all you need to connect your terminal to one of your pc's FREE serial ports. 

 

What you will need is:

  1. a usual RS-232 serial cable (like the one your external modem has to connect to your pc)

  2. a NULL MODEM which will be placed between your serial cable and the terminals port. DONT TRY to connect the serial cable to the pc and terminal directly because it DOESNT WORK THIS WAY , nor try to make up your own cable which will have the transmit and receive lines swapped, i have done all these and i failed dramatically, just go to your nearest electric shop and ask for a NULL modem it is really cheap.

(click to enlarge)

 

Do you have the serial cable and the null modem ? plug instantly your terminal to one of your pc's free serial ports and lets go to the LINUX configuration now. 

In General

Device File

MS-DOS Equivalent

Purpose

/dev/cua0
/dev/cua1
/dev/cua2
/dev/cua3

com1
com2
com3
com4

Used for out-going connections,
e.g. dialing out on a modem

/dev/ttyS0
/dev/ttyS1
/dev/ttyS2
/dev/ttyS3

com1
com2
com3
com4

Used for in-coming connections,
dialing in on a modem or a dumb terminal

Usual COMM configuration for terminals

 

Testing the connection

Now we will try to send some data to the terminal to see if works, lets say that your terminal is plugged into COM2 for dos or ttyS1 for linux, on the console window type the following

ls -l > /dev/ttyS1

If you see a clear output you did it !!!  if you dont, try to change the baud rate of your terminal. This command displays the directory listing on the screen of your terminal.

 

Final Step

Now that you made it you have to configure the linux box to use that port with the terminal, in other words you have to "tell" linux that in that port there is a terminal to "use"

You can do that by going to the /etc/ directory and find the inittab file then open it and edit it as follows.

You will see some lines like:

6:123:respawn:/etc/getty 38400 tty6
7:123:respawn:/etc/getty 38400 tty7
8:123:respawn:/etc/getty 38400 tty8

In the end of these lines ADD this line

S1:123:respawn:/etc/getty 9600 ttyS1

 

And thats it, do a restart on your linux box (/sbin/shutdown -r now) and if everything goes alright when the system restarts you will see on your terminal screen the LOGIN prompt. You can also change the motd and issue files in the /etc/ directory to suit your needs. The issue file is the title over the LOGIN prompt like nowasia.net, and the motd is what people see after they log in "Welcome bla bla" .

If you just bought an old terminal or have an old one which you dont know if it is working, it is better to see the next section "How to use your terminal with Microsoft Windows".

In this section you can firstly test your terminal's connection and configure it before you use it with linux, secondly and you can also use some the terminal for some Windows functions .

 

If something goes wrong and you still cant connect your terminal to your linux box or you dont understand somethign that i mention above feel free to email me directly.

 

Dumb Terminal Support Center :

How to use your terminal with Microsoft Windows

How to connect your serial terminal to a long distance without using RS-232

 

 

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