Black Box 3600 MODEM manual Terminal Interface Commands, Data Carrier Detect &C

AT Commands

When distinctive ring is enabled, one of the messages in Table 5-3 appears on the DTE instead of the regular RING message:

Table 5-3. Distinctive Ring Message s

The modem sends this
message...	If the Ring Was a:
RING A	Single ring (1 ring burst)
RING B	Double ring (2 ring bursts)
RING C	Triple ring (3 ring bursts)

Terminal Interface Commands

The EIA-232 interface connects the modem and DTE. Terminal interface commands control the action of the modem and the terminal in response to the signals being exchanged on the interface pins. Refer to Table 2-1.

Data Carrier Detect &C

When using DCD to indicate a valid carrier, use the &C1 command. Some terminals and other devices require DCD on in order to communicate with the modem; if so, use the &C command.

Command	Operation
&C	DCD always on
&C1	DCD on when modem recognizes remote modem
	carrier or, if enabled, when protocol negotiation is
	complete.
&C2	DCD on except for 5 seconds after disconnect
&C3	DCD follows RTS on remote modem (simulated
	switched carrier V.13).

Note

AT&C3 is used to simulate switched carrier operation.

Note

For simulated switched carrier operation &C3 must be selected on both modems. Not available in the B103 and V.21 modulation modes.

Modem 3600 5-19