[comp.unix.aix] How to connect a dial-out modem

fredrick@acd.acd.ucar.edu (Tim Fredrick) (04/12/91)

I got a lot of helpful answers to my question on setting up a dial-out modem
under AIX3.1.3002.  Thanks to everybody who replied.  Here is what I did
to get it to work based on these messages.  My examples use /dev/tty4.

   1. Cable has pins 1,2,3,4,5,6,7,8,20 and 22 wired straight through.

   2. Connect cable to modem and run smit with the power to the modem
      turned on.

   3. In SMIT set up the serial port (in our case tty4) with all of the
      defaults.  Disable logins.  Dial-in and Dial-out capability on the
      same modem isn't supported under AIX3.1.3002 or 3003.

   4. tip or kermit (at least the copy we have) won't work because it
      requires carrier detect to be held high -- my understanding is that
      can't happen with the way the hardware is currently defined.

   5. But "cu" works fine.  We put the following entries in our
      /usr/lib/uucp/Devices file:
             Direct tty4 - Any direct
             ACU tty4 - 2400 hayes \D

   6. And we put phone numbers in the /usr/lib/uucp/Systems file like this:
             atmos Any ACU 2400 9,5554321 - -
             beagle Any ACU 2400 9,5554322 - -

   7. Initially the modem must be configured to hangup the modem with
      a DTR signal.  This is done by entering "cu -l /dev/tty4 -b2400"
      and then:
      7a.  "at &f"                   ---- to fetch S registers from EPROM
      7b.  "at &d2&d3&c1             ---- d2 == modem goes on hook at
                                                returns to cmd mode on dtr off
                                          d3 == modem initializes w/dtr off
                                     ---- c1 == hardware carrier detect
      7c.  "at &w"                   ---- Write S registers to NV RAM
      7d.  Switch the modem off and on again.

   8. To use some systems that only connect at even-parity, we just
      use the "-e" flag on "cu".  For example "cu -e atmos".

BTW, replies also said I needed a null modem cable for attaching dumb terminals
that switch pins 2 & 3 and also exchange handshaking signals (DTR, CTS, DSR)
so that the two sides see the carrier signal.  One person said such a cable
is available from IBM.  I have not yet tried to get a dumb terminal to work.

Good Luck.  --Tim

robin@pensoft.uucp (Robin Wilson) (04/12/91)

In article <11020@ncar.ucar.edu> fredrick@acd.acd.ucar.edu (Tim Fredrick) writes:
)I got a lot of helpful answers to my question on setting up a dial-out modem
)under AIX3.1.3002.  Thanks to everybody who replied.  Here is what I did
)to get it to work based on these messages.  My examples use /dev/tty4.
)
)   2. Connect cable to modem and run smit with the power to the modem
)      turned on.

This is not required, but it doesn't really hurt anything.

)   3. In SMIT set up the serial port (in our case tty4) with all of the
)      defaults.  Disable logins.  Dial-in and Dial-out capability on the
)      same modem isn't supported under AIX3.1.3002 or 3003.
                                                    ^^^^^^^
It is not supported on 3002 (or before); it works fine on my version of 3003.

)   4. tip or kermit (at least the copy we have) won't work because it
)      requires carrier detect to be held high -- my understanding is that
)      can't happen with the way the hardware is currently defined.

You can strap carrier high on the modem by typing "AT&C0".  This will tell
HAYES "V-Series" modems to set carrier detect to "Always on".

)   7. Initially the modem must be configured to hangup the modem with
)      a DTR signal.  This is done by entering "cu -l /dev/tty4 -b2400"
)      and then:
)      7a.  "at &f"                   ---- to fetch S registers from EPROM
)      7b.  "at &d2&d3&c1             ---- d2 == modem goes on hook at
                ^^^^^^
				The first "&d" sets it to "2", and then you immediately 
                reset it to "3".  Just use one or the other.

)                                                returns to cmd mode on dtr off
)                                          d3 == modem initializes w/dtr off
)                                     ---- c1 == hardware carrier detect
)      7c.  "at &w"                   ---- Write S registers to NV RAM
)      7d.  Switch the modem off and on again.

This is not required, but it doesn't hurt anything.  (If you need to exit "cu"
just type "~." (tilde dot), and then press [ENTER].


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