How do I set up a terminal connected to my PC?

# 8 How do I set up a terminal connected to my PC?

Contents of this section

## 8.1 Hardware requirements

Make sure you have the right kind of cable. A null modem cable bought at a computer store will do it. But it must be a null modem cable! Make sure you are using your serial port, and not your parallel port.

At a minimum, you should have (for a DB25 connector):

            RxD   Receive Data          2 - 3       TxD   Transmit Data
            TxD   Transmit Data         3 - 2       RxD   Receive Data
            GND   Signal Ground         7 - 7       GND   Signal Ground

If you want to have flow control and hardware handshaking, you must have a full null modem cable:

                  Frame Ground          1 - 1             Frame Ground
            RxD   Receive Data          2 - 3       TxD   Transmit Data
            TxD   Transmit Data         3 - 2       RxD   Receive Data
            RTS   Request To Send       4 - 5       CTS   Clear To Send
            CTS   Clear To Send         5 - 4       RTS   Request To Send
            DSR   Data Set Ready        6 - 20      DTR   Data Terminal Ready
            GND   Signal Ground         7 - 7       GND   Signal Ground
            DCD   Carrier Detect        8 - 20      DTR   Data Terminal Ready
            DTR   Data Terminal Ready  20 - 6       DSR   Data Set Ready
            DTR   Data Terminal Ready  20 - 8       DCD   Carrier Detect

If you have a DB9 connector on your port, try the following:

                                      DB9   DB25
            RxD   Receive Data          2 - 3       TxD   Transmit Data
            TxD   Transmit Data         3 - 2       RxD   Receive Data
            GND   Signal Ground         5 - 7       GND   Signal Ground

Alternatively, a DB9-DB25 null modem cable:

                                      DB9   DB25
            DCD   Carrier Detect        1 - 20      DTR   Data Terminal Ready
            RxD   Receive Data          2 - 2       TxD   Transmit Data
            TxD   Transmit Data         3 - 3       RxD   Receive Data
            DTR   Data Terminal Ready   4 - 6       DSR   Data Set Ready
            DTR   Data Terminal Ready   4 - 8       DCD   Carrier Detect
            GND   Signal Ground         5 - 7       GND   Signal Ground
            DSR   Data Set Ready        6 - 20      DTR   Data Terminal Ready
            RTS   Request To Send       7 - 5       CTS   Clear To Send
            CTS   Clear To Send         8 - 4       RTS   Request To Send
            (RI Ring Indicator          9 not needed)

If you are not using a full null modem cable, you might have to do the following trick: on your computer side of the connector, connect RTS and CTS together, and also connect DSR, DCD and DTR together. This way, when the computer wants a certain handshaking signal, it will get it (from itself).

Now that you have the right kind of cable, connect your terminal to your computer. If you can, tell you terminal to ignore modem control signals. Try using 9600 bps, 8 data bits, 1 stop bit, no parity bits for the terminal's setup.

## 8.2 Setting up `getty`

Replace the stock `getty` with `getty_ps` as described in section What is `getty_ps`? . Add an entry for `getty` to use for your terminal in `/etc/gettydefs`:

> `

>     #9600 bps Dumb Terminal entry
>     DT9600# B9600 CS8 CLOCAL # B9600 SANE -ISTRIP CLOCAL #S @L login: #DT9600

> `

You can add `HUPCL` so the login is killed whenever you switch of the terminal (provided you use a proper null modem cable).

Edit your `/etc/inittab` file to run `getty` on the serial port (substituting in the correct information for your environment):

> `

>     S1:456:respawn:/etc/getty ttyS1 DT9600 vt100

> `

Restart `init`:

> `

>     linux# kill -HUP 1

> `

At this point, you should see a login prompt on your terminal. You may have to hit return a couple of times to get the terminal's attention. Rejoice. Party. Log in on your terminal and PC. `talk` to yourself from accross the room.

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