Modems

Modems provide serial communications across ordinary telephone lines. This section discusses modem standards, general modem setup, and specific configuration tips for popular modems.

Modem Overview

A modem is a device that allows you to connect one computer to another across ordinary telephone lines. The current telephone system is incapable of carrying the voltage changes required for a direct digital connection. A modem overcomes this limitation by modulating digital information into audio tones for transmission across the phone line, and by demodulating those tones back into digital information on reception. Modems are commonly used with Basic Network Utilities (BNU) or other implementations of the UNIX-to-UNIX Copy Program (UUCP). A high-speed (14,400 bps or greater) modem can be used with Serial Line Interface Protocol (SLIP) to provide Transmission Control Protocol/Internet Protocol (TCP/IP) connectivity as well.

Often, the term baud is used to refer to a modem's speed instead of bps. Baud is actually a measurement of the modulation rate. In older modems, only 1 bit was encoded in each signal change, so a modem's baud rate was equal to the modem's speed. Modems that operate at higher speeds, however, still generally operate at 2400 (or even 1200) baud, and encode two or more bits per signal change. A modem's bps rate is calculated by multiplying the number of data bits per signal with the baud (for example, 2400 baud x 6 bits per signal change = 14,400 bits per second). Most modern modems can communicate at a variety of speeds (for example, 14,400, 9600, 7800, 4800, and 2400 bps).

Telecommunications Standards

The older speeds of 300, 1200, and 2400 bps were well defined. However, as modem manufacturers began to devise methods for gaining higher speeds, each modem manufacturer started to use a proprietary method incompatible with modems from other manufacturers. Today, the ITU-TSS (formerly the United Nations Consultative Committee for International Telephony and Telegraphy, abbreviated CCITT) defines standards for most high-speed communications.

Even high-speed modems are much slower than other methods of computer communication. A high-speed modem may operate at 28,800 bps, but an Ethernet connection operates at 10,000,000 bps. In order to boost data throughput, high-speed modems typically offer one or more data compression algorithms. These algorithms can boost the throughput of a high-speed modem to speeds of 57,600 bps (if the data rate is 14,400 bps) or 115,200 bps (if the data rate is 28,800 bps). Note that these compression algorithms are sensitive to the data being transmitted. If the data has already been compressed (for example, with the compress command), the data compression methods of high-speed modems will offer little or no benefit, and might even reduce data throughput. When using a modem with data compression technology, the speed of the data terminal equipment/data circuit-terminating equipment (DTE/DCE) connection between the computer and the modem should be greater than the nominal data rate of the connection between modems, and equal . For example, with a V.32bis modem with V.42bis data compression, the data rate of the modem (the speed at which the modem communicates across telephone lines) is 14,400 bps. When the V.42bis compression is active, actual data throughput can reach 57,600 bps. To accommodate the greater throughput offered by data compression, the speed of the DTE/DCE between the computer and the modem should be set to 57,600 bps.

Attention: Some modems implementing data compression and modern modulation schemes may yield a higher data throughput than some systems and asynchronous adapters can accommodate.

Today, the ITU-TSS (formerly, the CCITT) defines standards for high-speed communications, including data compression algorithms. ITU-TSS standards are usually named V.nn, where nn is a number. Another, slightly less common standard is the Microcom Networking Protocol (MNP). Available in versions (called classes) 1-9, MNP is a high-performance, high-speed protocol that was available relatively early, and became something of a de facto standard before the advent of the CCITT standards.

ITU-TSS Communications Standards

Following is a list of some common communications standards defined by the ITU-TSS. Note that this only a partial list.

MNP Communications Standards

Generic Modems

To set up a modem:

1. Attach the modem with the appropriate cables.
2. Add a tty for the modem.
3. Configure the modem.

Attaching the Modem with Appropriate Cables

The first step in setting up a modem is to attach the modem with the appropriate cables. Part numbers and their descriptions are listed below.

Following are some examples of cable connections:

1. To attach a modem to native serial port S1, use the following cables:

   

2. To attach a modem to an 8-port async adapter (EIA-232) interface cable assembly, use the following cables:

   

3. To attach a modem to a 16-port concentrator on a 64-port adapter, use the following cables:

   

Adding a TTY for the Modem

First, ensure that the system is turned on and that the modem is turned off. Use the Web-based System Manager fast path, wsm devices, or the SMIT fast path smit mktty. Example port settings for the tty are given below:

Note that the port number, the baud rate, and the enabling of login depend on your setup:

• PORT number is dependent on the adapter/port to which the modem is attached.
• BAUD Rate is dependent on the capabilities of the modem.
• Enable LOGIN is dependent on port usage.

The Enable LOGIN parameter can have the following settings:

Configuring the Modem

Two methods for configuring the modem are presented in this section. You only need to use one method.

Sending AT Commands with the cu Command

If you have the Basic Network Utilities (BNU) installed, you can use the cu command to configure a modem as follows:

1. Add the following line to your /usr/lib/uucp/Devices file. Do not add the line if it is already in the file. This should work with most Hayes-compatible modems. (Replace # with the number for your port.)

   Direct tty# - Any direct

2. Enter the following commands (read the notes about each command before performing the command itself):

   pdisable tty#
   cu -l tty#	Use cu -ml tty# if ix24051 is installed for cu.
   AT&F	Restore the factory default configuration.
   ATE1	In command state, echo characters from the keyboard to the screen. (Make sure carrier is not ON on the port or modem.)

   Note: You need issue only one of the following commands.

   AT&D2	Monitor the data terminal ready (DTR) signal. When an on-to-off transition of the DTR signal occurs, the modem hangs up and enters the command state.
   AT&D3	Monitor the DTR signal. When an on-to-off transition of the DTR signal occurs, the modem hangs up and resets.
   AT&W	Write the storable parameters of the current configuration to the modem's memory.
   AT&C1	Track the status of the carrier detect signal. (The modem may disconnect.)

   Note: Issue the following command only if the previous command caused the modem to disconnect.

   cu -l tty#
   ATS0=1	Put the modem in autoanswer mode.
   ATS9=12	Set the carrier-detect response time. Default is 6. Possible values are 1 to 255.
   AT&W	Write the storable parameters of the current configuration to the modem's memory.
   ~.	Terminate the cu session.

3. Enter one of the following commands:

   penable  tty#
   pshare   tty#
   pdelay   tty#
   pdisable tty#

The modem now has the basic configuration needed for most system communications. If you have problems, invoke cu with the cu -dl command to start a diagnostic trace on the connection.

Sending AT Commands Using a C Program

If the previous method failed, or if you do not have BNU installed, try running the following C program. Create a file called motalk.c containing the following code. Save the file. Compile and run it according to the instructions in the program comments.

/*************************************************************/
/*  MoTalk - A "C" program for modem setup.                */
/*           This program is meant as an aid only and is   */
/*           not supported by IBM.                       */
/*                  compile:  cc -o motalk motalk.c       */
/*                  Usage:  motalk /dev/tty? [speed]      */
/*************************************************************/
#include <errno.h>
#include <stdio.h>
#include <signal.h>
#include <fcntl.h>
#include <termio.h>
FILE *fdr, *fdw;
int fd;
struct termio term_save, stdin_save;
void Exit(int sig)
{
   if (fdr) fclose(fdr);
   if (fdw) fclose(fdw);
   ioctl(fd, TCSETA, &term_save);
   close(fd);
   ioctl(fileno(stdin), TCSETA, &stdin_save);
   exit(sig);
}
main(int argc, char *argv[])
{
   char *b, buffer[80];
   int baud=0, num;
   struct termio term, tstdin;
   if (argc < 2 || !strcmp(argv[1], "-?"))
   {
      fprintf(stderr, "Usage: motalk /dev/tty? [speed]\n");
      exit(1);
   }
   if ((fd = open(argv[1], O_RDWR | O_NDELAY)) < 0)
   {
      perror(argv[1]);
      exit(errno);
   }
   if (argc > 2)
   {
      switch(atoi(argv[2]))
      {
         case   300: baud = B300;
                     break;
         case  1200: baud = B1200;
                     break;
         case  2400: baud = B2400;
                     break;
         case  4800: baud = B4800;
                     break;
         case  9600: baud = B9600;
                     break;
         case 19200: baud = B19200;
                     break;
         case 38400: baud = B38400;
                     break;
         default:    baud = 0;
                     fprintf(stderr, "%s: %s is an unsupported baud\n", argv[0],argv[2]);
                     exit(1);
         }
      }
   /* Save stdin and tty state and trap some signals */
   ioctl(fd, TCGETA, &term_save);
   ioctl(fileno(stdin), TCGETA, &stdin_save);
   signal(SIGHUP, Exit);
   signal(SIGINT, Exit);
   signal(SIGQUIT, Exit);
   signal(SIGTERM, Exit);
   /*  Set stdin to raw mode, no echo */
   ioctl(fileno(stdin), TCGETA, &tstdin);
   tstdin.c_iflag = 0;
   tstdin.c_lflag &= ~(ICANON | ECHO);
   tstdin.c_cc[VMIN] = 0;
   tstdin.c_cc[VTIME] = 0;
   ioctl(fileno(stdin), TCSETA, &tstdin);
   /*  Set tty state */
   ioctl(fd, TCGETA, &term);
   term.c_cflag |= CLOCAL|HUPCL;
   if (baud > 0)
   {
      term.c_cflag &= ~CBAUD
      term.c_cflag |= baud;
   }
   term.c_lflag &= ~(ICANON | ECHO); /* to force raw mode */
   term.c_iflag &= ~ICRNL; /* to avoid non-needed blank lines */
   term.c_cc[VMIN] = 0;
   term.c_cc[VTIME] = 10;
   ioctl(fd, TCSETA, &term);
   fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NDELAY);
   /*  Open tty for read and write */
   if ((fdr = fopen(argv[1], "r")) == NULL )
   {
      perror(argv[1]);
      exit(errno);
   }
   if ((fdw = fopen(argv[1], "w")) == NULL )
   {
      perror(argv[1]);
      exit(errno);
   }
   /*  Talk to the modem */
   puts("Ready... ^C to exit");
   while (1)
   {
      if ((num = read(fileno(stdin), buffer, 80)) > 0)
         write(fileno(fdw), buffer, num);
      if ((num = read(fileno(fdr), buffer, 80)) > 0)
         write(fileno(stdout), buffer, num);
      Exit (0);
   } 
} 

Hayes and Hayes-Compatible Modems

1. Change the tty settings using the Web-based System Manager fast path, wsm devices, or the SMIT fast path, smit chtty.

   Example settings for the modem follow. (tty0 is the tty for this example and the baud rate may be changed depending on your modem. Generally, you want to keep the baud rate at the highest speed that the modem can allow.)

   TTY	tty0
   TTY type	tty
   TTY interface	rs232
   Description	Asynchronous Terminal
   Status	Available
   Location	00-00-s1-00
   Parent adapter	sa0
   PORT number	s1
   Enable LOGIN	share
   BAUD rate	2400
   PARITY	none
   BITS per character	8
   Number of STOP BITS	1
   TIME before advancing to next port setting	0
   XON-XOFF handshaking	no
   TERMINAL type	dumb
   INPUT map file	none
   OUTPUT map file	none
   CODESET map file	sbcs

   STTY attributes for RUN TIME should be:

   [hupcl,cread,brkint,icrnl,opost,tab3,onlcr,icanon,echo,echoe,echok,echoctl, 
   echoke,imaxbel,iexten]

   (No ixon/ixoff needed)

   STTY attributes for LOGIN should be:

   [hupcl,cread,echoe,cs8]

   (No ixon/ixoff needed)

2. Add the following line to /usr/lib/uucp/Systems file:

   hayes Nvr HAYESPROG 2400

3. Add this to /usr/lib/uucp/Devices file:

   # For programming the  hayes modem only:
   HAYESPROG tty0 - 2400 HayesProgrm2400
   #regular ACU entry:
   ACU tty0 - Any hayes
    

4. Add this to /usr/lib/uucp/Dialers file:

   # This Entry is used to PROGRAM the modem ONLY:
   # the next 3 lines should be made into one:
   HayesProgrm2400     =,-,     "" \d\dAT\r\c OK AT&F\r\c OK ATM1\r\c OK 
   AT&D3\r\c OK AT&K3&C1\r\c OK ATL0E0Q2\r\c OK ATS0=1\r\c OK AT&W\r\c 
   OK
   hayes     =,-,     "" \dAT\r\c OK ATDT\T\d\r\c CONNECT

5. To program the modem, enter the command cu -d hayes . This command uses cu to program the modem. Since no connection is made to another system, the command will fail. The modem will be programmed if sendthem AT&W and then OK got it appear in the output.

   If you are not doing binary file transfers or using BNU, leave out the &K3 command, and set XON-XOFF handshaking to Yes in SMIT or checked in Web-based System Manager. However, it is more efficient to use hardware flow control (as opposed to XON-XOFF handshaking). To do that, use the settings and the Dialers entries from step 5.

After the modem is programmed, you must set request to send (RTS) line discipline to allow the system device driver to use hardware flow control. To do that, the modem must be connected to another system (to bring carrier high) and the following command must be run:

stty add rts < /dev/tty0

Be sure to substitute tty0 with your tty number. This works until the next reboot, when it must be done again. For the addition of RTS to be done automatically at system startup, type in and compile the addrts.c program that follows, and place a line in /etc/rc that calls the program on system startup. (This program does not require carrier to be high.) The command is:

addrts /dev/tty0

The full path to the command must be specified if the addrts program is not in one of the directories in the PATH. (Substitute your tty number for tty0 above.)

Adding RTS Discipline to TTY Ports

/*             C Program to add RTS discipline to tty port(s). 

   Tips:  
         To make the program more permanent, insert the file name of
         the compiled version (complete with path) at the end of your
         "/etc/rc" file and the changes will take effect again at next
         reboot. 
          
         NOTE: This program is supplied "as is" and is NOT supported by
               IBM.  It is intended as an aid to administrators only.
               
 _________________________________________________________________    
     To create:     vi addrts.c <enter>
     To compile:    cc -o addrts  addrts.c 
     Usage is:      addrts /dev/tty##
 ________________________________________________________________ */
/*                         Program starts now                  */
#include <stdio.h>  
#include <fcntl.h> 
#include <termios.h> 
#include <sys/tty.h> main (argc,argv)
{
   int argc;
   char *argv[];
   int fd;
   if ( (fd = open(argv[1], O_NDELAY|O_RDWR)) <0 )
   {
      printf("%s: could not open %s\n",argv[0],argv[1]);
      exit (22);
   }
   ioctl(fd, TXADDCD, "rts");
   /*  adds rts to the tty in the argument */
   close(fd); 
}

Specific Modem Configuration Tips

Following are some specific configuration tips and setup information for a variety of popular modems.

Setup Information for the IBM 7855 Modem

Note: This guide uses tty0 as an example. Substitute the tty to which the modem is attached for tty0 .

To use the IBM 7855 modem as a dial-in or dial-out modem on the system, the modem must be set to accept AT commands. To do this, press the right and left arrow keys on the front of the modem at the same time. The front panel should then read:

<Exit     Enter>

Press the right arrow to enter, and the down arrow until you see First Setup ; t hen the right arrow. Press the up arrow until you see Asynchronous AT. Press the left arrow until you exit out of the setup menu.

1. Change the tty settings using the Web-based System Manager fast path, wsm devices, or the SMIT fast path, smit chtty.
2. Select the tty for the modem, and make the appropriate changes. Example settings follow:

   Note: Options that are not needed are not included in the following list.

   TTY	tty0
   TTY type	tty
   TTY interface	rs232
   Description	Asynchronous Terminal
   Status	Available
   Location	00-00-s1-00
   Parent adapter	sa0
   PORT number	s1
   Enable LOGIN	share
   BAUD rate	19200
   PARITY	none
   BITS per character	8
   Number of STOP BITS	1
   TIME before advancing to next port setting	0
   XON-XOFF handshaking	no
   TERMINAL type	dumb
   INPUT map file	none
   OUTPUT map file	none
   CODESET map file	sbcs

   STTY attributes for RUN TIME should be:

   [hupcl,cread,brkint,icrnl,opost,tab3,onlcr,icanon,echo,echoe,echok, echoctl,echoke,imaxbel,iexten]

   (No ixon/ixoff needed)

   STTY attributes for LOGIN should be:

    [hupcl,cread,echoe,cs8]

   (No ixon/ixoff needed)

3. Add the following two lines to /usr/lib/uucp/Systems file (be sure to start in the leftmost column):

   ibm7855 Nvr IBMPROG 19200
   slip Nvr SLIPPROG 19200

4. Add the following lines to /usr/lib/uucp/Devices file (be sure to start in the leftmost column):

   IBMPROG tty0 - Any IBMProgrm
   SLIPPROG tty0 - Any SlipProgrm
    
   # Usual ACU entry
   ACU tty0 - Any ibm
    
   # ACU entry to quietly dial the modem.
   ACUQ tty0 - Any ibmq
    
   # IBM7855 ACU entry to negotiate for error correction and compression
   ACUECLC tty0 - Any ibmeclc
    
   # IBM7855 ACU entry to negotiate for error correction and compression
   # using large (256 byte) data block size
   ACUECLB tty0 - Any ibmeclclb
    
   # IBM 7855 ACU entry to use ECL without compression
   ACUECL tty0 - Any ibmecl

5. Add the following lines to /usr/lib/uucp/Dialers file (be sure to start in the leftmost column):

   # IBM 7855 program. Use ibmeclcbc for 256 byte block size.  However,
   # Noisey lines may obtain better throughput by setting the block size to
   # be 64 bytes; compressed files will show better throughput by turning off
   # compression.
   # The following 3 lines should be joined into one line:
   IBMProgrm       =,-,    "" \dATQ0\r\c OK AT&F\r\c OK ATM1\r\c OK
   AT&D3\r\c OK AT&C1\R2\Q2\M14\r\c OK AT&B8N1L0E0\r\c OK ATS0=1\r\c
   OK ATQ1&W0&Y0\r\c ""
    
   # The following 3 lines should be joined into one line:
   SlipProgrm      =,-,    "" \dATQ0\r\c OK AT&F\r\c OK ATM1\r\c OK
   AT&D3\r\c OK AT&C0\R2\Q2\r\c OK AT&B8N1L0E0\r\c OK
   ATS0=1\r\c OK ATQ1&W\r\c ""
    
   ibm     =,-,    "" \dATQ0\r\c OK ATDT\T\d\r\c CONNECT
   ibmq    =,-,    "" \dATQ0\r\c OK ATM0DT\T\d\r\c CONNECT
    
   #IBM 7855 with ECLC and Compression
   # (Note two backslashes are needed before the N; cu won't send \N
   # without preceeding it with a \)
   ibmeclc =,-,    "" \dAT\\N3%C1Q0\r\c OK ATDT\T\d\r\c CONNECT
    
   #IBM 7855 ECLC Compression with 256 byte block size
   ibmeclclb       =,-,    "" \dAT\\N3%C1Q0\A3\r\c OK ATDT\T\d\r\c CONNECT
    
   # IBM 7855 ECL without compression
   ibmecl  =,-,    "" \dAT\\N3%C0Q0\r\c OK ATDT\T\d\r\c CONNECT

Programming the IBM 7855

1. Disable the port (temporarily) with this command: pdisable tty0.
2. On the command line enter cu -d ibm7855 .

   The command fails because no one is connected, but if the following is in the output:

   Sendthem (ATQ1&W0&Y0^MNO CR)
   expect: ("")
   got it

   it is successfully programmed. The LED on the front should read ASYN8N A 9600 a . You can then pshare tty0 .

After the modem is programmed, you can set RTS line discipline to allow hardware flow control. To do that, the modem must be connected to another system (to bring carrier high) and the following command must be run:

stty add rts < /dev/tty0

Be sure to substitute tty0 with your tty number. This will be good until the next system startup, then it will need to be done again.

Alternatively, you could type in and compile the addrts.c program, listed below, and place a line in /etc/rc that will call the program on system startup to add RTS to the line. This program does not require carrier to be high.

/*             C Program to add RTS discipline to tty port(s).

     Tips:
          To make the program more permanent, insert the file name of
          the compiled version (complete with path) at the end of your
          "/etc/rc" file and the changes will take effect again at next
          reboot.  Usage is addrts /dev/tty##.


          NOTE: This program is supplied "as is" and is NOT supported by
                IBM.  It is intended as an aid to administrators only.
 _______________________________________________________________________
     To create:     vi addrts.c <enter>
     To compile:    cc -o addrts  addrts.c
 _______________________________________________________________________ */
/*                         Program starts now                  */
#include <stdio.h>
#include <fcntl.h>
#include <termios.h>
#include <sys/tty.h>
main (argc,argv)
        int argc;
        char *argv[];
{
        int fd;
        if ( (fd = open(argv[1], O_NDELAY|O_RDWR)) <0 ) {
                printf("%s: could not open %s\n",argv[0],argv[1]);
                exit (22);
                }
        ioctl(fd, TXADDCD, "rts");  /*  adds rts to the tty in the argument */
        close(fd);
}

Setup Information for the MultiTech MULTIMODEM II

1. Use the L5, L6, and L7 AT commands to view the following modem parameters.

   ATL5
   B1 E1 M1 Q0 R0 V1 X0 &E1 &E4 &E6 &E8 &E10 &E13 &E15
   $MB9600 $SB9600 $BA0 &W0
    
   OK
   ATL6
   S0   S2   S3   S4   S5   S6   S7   S8   S9   S10  S11  S13  S24  S25  S30
   001  043  013  010  008  002  045  002  025  007  070  037  020  001  000
    
   OK
   ATL7
   $A0 &A0 #A0 &B0 &BS1 &C1 $D0 &D2 #DB0 $EB0 %E1 #F0 $F1 &G0 #L0 $MI0 &M0
   &P0 #P2 &Q0 $R0 &R1 &RF1 &S0 $SP0 &SF0 #T1 $V0 $V6 $VD0 &X0 Y0
   $MB9600 $SB9600 $BA0 &W0
   OK

   Note: In the example above, the s9 register has been set to 25. The default is 6. The normal setting should be between 15 and 20.

2. Modems that are set for baud rates at or above 9600 should have RTS/CTS (request to send/clear to send) hardware handshaking added to the tty port. There are two options for accomplishing this:
   1. Use the following procedure:
      • Add clocal to the stty Attributes for Runtime for your tty using smit chtty.
      • On the command line, enter: pdisable tty N (N is your tty number).
      • Issue the command stty add rts < /dev/tty N
      • Issue the command stty get < /dev/tty N . RTS should appear on line.
   2. Use the following C program to add RTS to the port.

      /*  C Program to add RTS discipline to tty port(s).
      
        NOTE: This program is supplied "as is" and is NOT supported by
              IBM.  It is intended as an aid to administrators only.    */
      /*                         Program starts now                    */
      #include <stdio.h>
      #include <fcntl.h>
      #include <termios.h>
      #include <sys/tty.h>
      main()
      {
         int fd;
            fd = open("/dev/tty0", O_NDELAY|O_RDWR);
            ioctl(fd, TXADDCD, "rts");      /*  adds rts to tty0       */
            close(fd);
      }
      /*                           END Program                         */

Setup Information for a Practical Peripherals Modem

1. Change the tty settings using the Web-based System Manager fast path, wsm devices, or the SMIT fast path, smit chtty.
2. Select the tty for the modem and make the appropriate changes. (tty0 is the tty for this example and the baud rate may be changed depending on your modem. Generally, you want to keep the baud rate at the highest speed that the modem can allow.) Example settings follow:

   Note: Options that are not necessary are not included in the following list.

   TTY	tty0
   TTY type	tty
   TTY interface	rs232
   Description	Asynchronous Terminal
   Status	Available
   Location	00-00-s1-00
   Parent adapter	sa0
   PORT number	s1
   Enable LOGIN	share
   BAUD rate	2400
   PARITY	none
   BITER per character	8
   Number of STOP BITS	1
   TIME before advancing to next port setting	0
   XON-XOFF handshaking	no
   TERMINAL type	dumb
   INPUT map file	none
   OUTPUT map file	none
   CODESET map file	sbcs

   STTY attributes for RUN TIME should be:

   [hupcl,cread,brkint,icrnl,opost,tab3,onlcr,icanon,echo,echoe,echok, 
   echoctl,echoke,imaxbel,iexten]

   (No ixon/ixoff needed)

   STTY attributes for LOGIN should be:

   [hupcl,cread,echoe,cs8]

   (No ixon/ixoff needed)
3. Add the following line to /usr/lib/uucp/Systems file:

   pracper Nvr PRACPERPROG 2400

4. Add this to /usr/lib/uucp/Devices file:

   # For programming the Practical Peripherals modem only:
   PRACPERPROG tty1 - 2400 PracPerProgram2400
    
   # regular ACU entry:
   ACU tty1 - Any hayes

5. Add this to /usr/lib/uucp/Dialers file:

   # This Entry is used to PROGRAM the modem ONLY:
   # the next 3 lines should be made into one:
   PracPerProgram2400      =,-,    "" \d\dAT\r\c OK AT&F\r\c OK ATM1\r\c OK
   AT&D3\r\c OK AT&C1\r\c OK ATL0E0\r\c OK ATS0=1S9=20\r\c OK AT&W\r\c
   OK
    
   hayes   =,-,    "" \dAT\r\c OK ATDT\T\d\r\c CONNECT

6. To program the modem, enter the command cu -d pracper . cu is used to program the modem. Because there is no connection to another computer, the command fails. The modem will be programmed if you see sendthem AT&W and then OK got it in the output.

After the modem is programmed, you can set RTS line discipline to allow hardware flow control. To do that, the modem must be connected to another system (to bring carrier high) and the command stty add rts < /dev/tty0 must be run. (Be sure to substitute tty0 with your tty number). This works until the next system restart, when it must be done again. Alternately, type in and compile the addrts.c program, and place a line in /etc/rc that calls the program on system startup. This program does not require carrier to be high.

Setup Information for the Telebit T1600 Modem

1. Add this to /usr/lib/uucp/Systems file:

   telebit Nvr TELEPROG 19200

2. Add this to /usr/lib/uucp/Devicesca file:

   #
   #  Devices entry to use to program the T1600
   #
   TELEPROG tty0 - 19200 TelebitProgram
   #
   #  19200, 9600 baud (fast) Telebit Trailblazer modem
   #
   ACU       tty0 - 19200 tbfast \D
   ACUTB     tty0 - 19200 tbfast \D
   ACU96     tty0 - 9600 tbfast \D
   #
   #  2400 baud Telebit Trailblazer modem
   #
   ACU       tty0 - 2400 tb2400 \D
   ACU24     tty0 - 2400 tb2400 \D
   #
   #  1200 baud Telebit Trailblazer modem
   #
   ACU       tty0 - 1200 tb1200 \D
   ACU12     tty0 - 1200 tb1200 \D

3. Add this to /usr/lib/uucp/Dialers file:

   #
   # Entry to program the modem ONLY
   # The next 3 lines should be made into one long line:
   TelebitProgram  =,-,    "" \dAT&F\r\c OK
   ats0=1s2=255s7=60s11=50s41=2s45=255s51=252s63=1s58=2s64=1\r\c OK
   ATs69=2s105=0s111=30s255=0M0&C1Q2&D3&Q0&R3&S1&T5\r\c OK ATE0X12&W\r\c OK
   #
   # Telebit T1600 Dialers entries
   #
   tbfast  =,-,    "" \dATs50=255s7=60\r\c OK\r ATDT\T\r\c CONNECT-\d\c-CONNECT
   tb2400  =,-,    "" \dATs50=3\r\c OK\r ATDT\T\r\c CONNECT
   tb1200  =,-,    "" \dATs50=2\r\c OK\r ATDT\T\r\c CONNECT

4. To program the modem, enter the command cu -d telebit . The cu command will think it is connecting to a system, so it will fail. Watch the command's output to make sure that an OK is received.

Configuration Information for the Telebit T2000 Modem

1. Add this to /usr/lib/uucp/Systems file:

   telebit Nvr TELEPROG 19200

2. Add this to /usr/lib/uucp/Devices file:

   #
   #  Devices entry to use to program the T2000
   #
   TELEPROG tty0 - 19200 TelebitProgram
   #
   #  19200, 9600 baud (fast) Telebit Trailblazer modem
   #
   ACU       tty0 - 19200 tbfast \D
   ACUTB     tty0 - 19200 tbfast \D
   ACU96     tty0 - 9600 tbfast \D
   #
   #  2400 baud Telebit Trailblazer modem
   #
   ACU       tty0 - 2400 tb2400 \D
   ACU24     tty0 - 2400 tb2400 \D
   #
   #  1200 baud Telebit Trailblazer modem
   #
   ACU       tty0 - 1200 tb1200 \D
   ACU12     tty0 - 1200 tb1200 \D
   #
   #  For sites with MNP modems
   #
   ACUM12     tty0 - 1200 tb12mnp \D
   ACUM24     tty0 - 2400 tb24mnp \D

3. Add this to /usr/lib/uucp/Dialers file:

   #
   # Entry to program the modem ONLY
   #
   # The next 4 lines will be made into one:
   TelebitProgram  =,-,    "" \dAT&F\r\c OK
   ats2=255s7=60s11=50s41=2s45=255s51=252s52=2s54=3s58=2s64=1\r\c OK
   ATs69=1s92=1s96=0s105=0s110=1s111=30s130=3s131=1F1M0Q6TV1W0X3Y0&P0&T5\r\c
   OK ATE0&W\r\c OK  00
   #
   # Telebit T2000 dialers Entries:
   #
   tbfast  =,-,    "" \dATs50=255s7=60\r\c OK\r ATDT\T\r\c CONNECT-\d\c-CONNECT
   tb2400  =,-,    "" \dATs50=3\r\c OK\r ATDT\T\r\c CONNECT
   tb1200  =,-,    "" \dATs50=2\r\c OK\r ATDT\T\r\c CONNECT
   tb24mnp =,-,    "" \dAT\r\c OK ATS0=0S95=2S50=3S41=0\r\c OK ATDT\T\r\c CONNECT
   tb12mnp =,-,    "" \dAT\r\c OK ATS0=0S95=2S50=2S41=0\r\c OK ATDT\T\r\c CONNECT

4. To program the modem, enter the command cu -d telebit . The cu command will think it is connecting to a system, so it will fail. Watch the command's output to make sure that an OK is expected it is received.

Setup Information for the Telebit T3000 Modem

1. Add this to /usr/lib/uucp/Systems file:

   telebit Nvr TELEPROG 19200

2. Add this to /usr/lib/uucp/Devices file:

   #
   #  Devices entry to use to program the T3000
   #
   TELEPROG tty1 - 19200 TelebitProgram
   #
   #  19200, 9600 baud (fast) Telebit Trailblazer modem
   #
   ACU       tty1 - 19200 tbfast \D
   ACUTB     tty1 - 19200 tbfast \D
   ACU96     tty1 - 9600 tbfast \D
   #
   #  2400 baud Telebit Trailblazer modem
   #
   ACU       tty1 - 2400 tb2400 \D
   ACU24     tty1 - 2400 tb2400 \D
   #
   #  1200 baud Telebit Trailblazer modem
   #
   ACU       tty1 - 1200 tb1200 \D
   ACU12     tty1 - 1200 tb1200 \D
   #
   #  For sites with MNP modems
   #
   ACUM12     tty1 - 1200 tb12mnp \D
   ACUM24     tty1 - 2400 tb24mnp \D

3. Add this to /usr/lib/uucp/Dialers file:

   #
   # Entry to program the modem ONLY
   # The following 4 lines should be made into one long line:
   TelebitProgram  =,-,    "" \dAT&F\r\c OK
   ats0=1s2=255s7=60s11=50s41=2s45=255s51=252s63=1s58=2s64=1\r\c OK
   ATs69=2s105=0s111=30s255=0M0&C1Q2&D3&Q0&R3&S1&T5\r\c OK ATE0X12&W\r\c
   OK  00
   #
   # Telebit T2000 dialers Entries:  The tbfast won't work for the T3000,
   # but the rest should.
   #
   tbfast  =,-,    "" \dATs50=255s7=60\r\c OK\r ATDT\T\r\c CONNECT-\d\c-CONNECT
   tb2400  =,-,    "" \dATs50=3\r\c OK\r ATDT\T\r\c CONNECT
   tb1200  =,-,    "" \dATs50=2\r\c OK\r ATDT\T\r\c CONNECT
   tb24mnp =,-,    "" \dAT\r\c OK ATS0=0S95=2S50=3S41=0\r\c OK ATDT\T\r\c CONNECT
   tb12mnp =,-,    "" \dAT\r\c OK ATS0=0S95=2S50=2S41=0\r\c OK ATDT\T\r\c CONNECT

4. To program the modem, enter the command cu -d telebit . The command will fail because no connection is established. Examine the debug output of the command to verify that ATE0X12&W was sent and that OK was received. This indicates the modem is programmed.

Setup Information for UDS Modems

1. Change the tty settings using the Web-based System Manager fast path, wsm devices, or the SMIT fast path, smit chtty.
2. Select the tty for the modem, and make the appropriate changes. Example changes follow (tty0 is the tty for this example):

   Note: Options that are not necessary are not included.

   TTY	tty0
   TTY type	tty
   TTY interface	rs232
   Description	Asynchronous Terminal
   Status	Available
   Location	00-00-s1-00
   Parent adapter	sa0
   PORT number	s1
   Enable LOGIN	share
   BAUD rate	19200
   PARITY	none
   BITS per character	8
   Number of STOP BITS	1
   TIME before advancing to next port setting	0
   XON-XOFF handshaking	no
   TERMINAL type	dumb
   INPUT map file	none
   OUTPUT map file	none
   CODESET map file	sbcs

   STTY attributes for RUN TIME should be:

   [hupcl,cread,brkint,icrrnl,opost,tab3,onlcr,icanon,echo,echoe,echok, echoctl, 
   echoke,imaxbel,iexten]

   (No ixon/ixoff needed)

   STTY attributes for LOGIN should be:

   [hupcl,cread,echoe,cs8]

   (No ixon/ixoff needed)
3. Add the following line to /usr/lib/uucp/Systems file:

   uds Nvr UDSPROG Any

4. Add this to /usr/lib/uucp/Devices file:

   ------------begin text to insert--------
   # For programming the UDS modem only:
   UDSPROG tty0 - 9600 udsmodemPROGRAM
    
   # regular ACU entry:
   ACU tty0 - Any uds
   -------------end text to insert---------
    
   **  Add this to /usr/lib/uucp/Dialers file:  **
    
   ------------begin text to insert--------
   # the next 2 lines should be made into one:
   udsmodemPROGRAM =,-,    "" \dAT&FQ2\r\c OK ATE0Y0&C1&D2&S1%B5%E0*LC\r\c
   OK AT&W\r\c OK
    
   uds    =,-,    "" \dAT\r\c OK\r ATDT\T\d\r\c CONNECT

5. To program the modem, enter the command cu -d uds . The cu command is used to program the modem. Because there is no connection to another computer, the command fails. Watch the output of the command to see this.

Setup Information for the Telebit T3000 90202-01 WordBlazer Modem

When using the T3000 modem on a 128-port concentrator (operating at AIX level 3.2.3 Extended), change the tty settings using the Web-based System Manager fast path, wsm devices, or the SMIT fast path, smit chtty and change the following settings, both in the user interface and on the modem. Please do not use the 38400 baud rate shown below unless your serial hardware can support this speed. Make changes to baud speeds accordingly.

Example settings follow (only entries that must be changed are shown):

tty settings for modem on 128-port adapter:

Suggested settings for modem registers and commands:

Notes:

1. Use AT&V with this modem to view current values.
2. Change register 51 to reflect your hardware DTE speed.
3. Register 92 is very important if you will be connecting to modems operating at lower speeds. The suggested setting is 1.

Troubleshooting Modem Problems

This section attempts to identify common problems when using a modem with your computer.

Software Services Modem Questionnaire

Before calling for assistance with modem problems, please collect the following information:

• System Xtra?
• Level of the operating system. How long have you been at this level of the operating system?
• Has the modem ever worked before?
• What type of modem are you using? What type of modem is on the other end of the telephone connection?
• To what adapter type (64-port. 128-port, S1,...) is the modem attached?
• To which port number is the modem attached?
• To which tty number is the modem attached?
• What type of cabling are you using?
• What is the login setting (share, delay, enable)?
• Can the modem connect to other modems?
• Can other modems connect to your modem?
• What are the following values in Web-based System Manager, SMIT, modem, or port?
  • XON/XOFF?
  • RTS/CTS?
  • BPS rate?
• Include the following in your problem description:
  • Does the port lock intermittently?
  • Can you dial out? Can others dial in?
  • Any other specific and descriptive error conditions.
• Are there errors on the console? What are they?
• Are there errors in the error report? (errpt or errpt -a)
• What command are you using to dial out?
• What software is involved on the system?

AT Command Summary

The following is a summary of the Hayes Smartmodem command set. These commands comprise the AT command set used by many popular modems. This information comes from the Hayes Smartmodem 2400 Quick Reference Card, published by Hayes Microcomputer Products, Inc.

S-Register Summary

Result Codes Summary

Dial modifiers

The following lists and describes dial modifiers.