Product data

USRobotics
Command Reference
Syntax and Procedures - 11
the same parity and format.
The modem will ignore any command line that is not properly terminated. The
modem may consider 30 seconds of mark idle time between any two characters
as an improperly terminated command line. In this case the modem may or may
not generate an ERROR message. The modem will ignore any characters
received from the DTE that are not part of a properly-formatted command line.
If the maximum number of characters that the modem can accept in the body is
exceeded, an ERROR result code is generated after the command line is
terminated.
The DTE will not begin issuing a subsequent command line until at least one-tenth
of a second has elapsed after receipt of the entire result code issued by the
modem in response to the preceding command line.
Executing Commands
Upon receipt of the termination character, the modem commences execution of
the commands in the command line in the order received from the DTE. Should
execution of a command result in an error, or a character be not recognized as a
valid command, execution is terminated, the remainder of the command line is
ignored, and the ERROR result code is issued. Otherwise, if all commands
execute correctly, only the result code associated with the last command is
issued; result codes for preceding commands are suppressed. If no commands
appear in the command line, the OK result code is issued.
Aborting Commands
Some action commands that require time to execute may be aborted while in
progress; these are explicitly noted in the description of the command. Aborting of
commands is accomplished by the transmission from the DTE to the modem of
any character. A single character is sufficient to abort the command in progress;
however, characters transmitted during the first 125 milliseconds after
transmission of the termination character are ignored (to allow for the DTE to
append additional control characters such as line feed after the command line
termination character). To ensure that the aborting character is recognized by the
modem, it should be sent at the same rate as the preceding command line; the
modem may ignore characters sent at other rates. When such an aborting event
is recognized by the modem, the modem terminates the command in progress
and returns an appropriate result code to the DTE, as specified for the particular
command.
Handling of Invalid Numbers and S-Parameter Values
The modem reacts to undefined numbers and S-parameter values in one of three
ways:
• Issue the ERROR result code, and leave the previous value of the