Technical data

Managing Peripheral Devices
8.7 Managing Modems
3. Determine the command set used by the modem.
The command set includes the commands used to request that the modem
place a telephone call, the telephone number to be called, and the commands
used to configure the modem.
Examples of command sets follow:
• AT command set:
ATDT phone-number
where:
AT indicates ‘‘attention’’—to get the attention of the modem
DT indicates ‘‘dial tone’’; (PT would indicate ‘‘pulse tone’’).
• DMCL command set:
Ctrl/B
Return
Ready
DIAL T phone-number
where:
T represents ‘‘tone’’; (P would represent ‘‘pulse’’).
phone-number represents the phone number you are dialing.
The command set is used to communicate with the modem to request that
the modem perform some action, such as dialing a telephone number and
connecting to a remote modem. You can enter direct modem commands at a
terminal directly connected to a modem, or you can communicate indirectly
with the modem using DCL commands such as SET HOST/DTE.
4. Configure the port.
After wiring the modem to the connector on the OpenVMS computer or
DECserver, you must configure the port to recognize and properly operate the
modem, and to enable autobaud speed detection.
Note
The autobaud operation detects the speed—the baud rate—of the
communications. Including the /AUTOBAUD qualifier is not required;
however, if autobaud detection is disabled, you must configure both the
host terminal or DECserver port, and the modem, for the same baud rate.
The commands you give depend on whether you are using an OpenVMS host
system or a DECserver:
• On an OpenVMS host system, execute the following command
interactively, and also place this command in the system-wide startup
file, SYS$MANAGER:SYSTARTUP_VMS.COM:
$ SET TERMINAL /MODEM /AUTOBAUD /PERMANENT TTAO:
where TTA0: is the name of the terminal device the modem is wired to.
This command requires privileges.
8–32 Managing Peripheral Devices