Functional Modes - Multitech MultiModem II BA-Series User Manual

Chapter 5 - Command Mode
5.1.2

Functional Modes

The MultiModem can be in one of two functional states (see Figure 5-1). These are "Command
mode" and "On-line mode". (There is also an in-between state, "Wait-for-Carrier", where the modem
is out of Command mode but not yet really On-Line.
When the modem is initially powered up, it is in Command mode and is ready to accept commands
from your keyboard or software. The modem enters On-line mode after dialing, making a connection
with another modem, and then detecting a valid carrier signal. If no carrier is detected within a certain
time frame, the modem abandons the call and re-enters Command mode.
Once on line, the modem exits On-line mode if one of two conditions is met. If the carrier is lost or
intentionally dropped, the modem hangs up and re-enters Command mode. Also, if the modem
recognizes the Escape sequence for which it is configured (i.e., either the Escape characters in the
serial data stream, the Remote Escape characters in the modulated data stream, or the Break
signal), the modem will exit On-line mode, retain the datacomm link, and enter Command mode.
You can force the modem into On-line mode without dialing by sending the ATD or ATA command to
the modem.
Figure 5-1. Functional Modes
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