Data Carrier Detect (&C); Data Set Ready (&S) - Black Box 325 User Manual

6.9.1 D C D
ATA ARRIER
When using DCD to indicate a valid carrier, enter AT&C1. Some terminals and other devices require
DCD on to communicate with the modem; if so, select &C.
Command
&C
&C1
&C2
&C3
†default
AT&C3 simulates switched-carrier operation.
For simulated switched carrier-operation, &C3 must be selected on both modems. (Only
available in V.32 direct or synchronous mode.)
6.9.2 D S R
ATA ET EADY
These commands control the DSR signal generated by the modem to indicate that the modem is ready
for operation. DSR must be on for some terminals and devices to communicate with the modem.
Command
&S
&S1
&S2
&S3
†default
(&C)
ETECT
Table 6-7. Data Carrier Detect (&C).
Operation
DCD always on†
DCD is on when the modem recognizes remote modem carrier or, if enabled,
when MNP negotiation is complete
DCD on except for 5 seconds after disconnect
DCD follows RTS on remote modem (simulated switched carrier)
(&S)
Table 6-8. Data Set Ready (&S).
CHAPTER 6: Asynchronous Operating Commands
NOTE
Description
DSR always on†
DSR on when off hook in data mode
DSR off for 5 seconds after disconnect then returns to on
DSR follows OH (off hook)
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