Chapter 7: AT Commands and Registers
7-12 CSMIM-T1 Hardware Installation Guide
Table 7-1 The &C and \D Settings
NOTES Hardware flow control overrides &C and \D settings for CTS.
(See \Q.)
The modem ignores &C and \ D settings while connected in
V.23 half-duplex direct mode (%F3).When \D4 is set, &D
should be set to a value greater than 0.
ITU-T recommends that DSR come On when establishing a
connection and drop when the connection ends. It is also
recommended that CTS follow DTR while in command state;
drop either when answer tone is detected when originating,
when going off hook when answering, or when connection
ends; and follow connection status during connection.
&C \D Result
0 0 DCD On, DSR On, CTS On
0 1 DCD On, DSR On, CTS On
0 2 DCD On, DSR On, CTS On
0 3 DCD On, DSR complies with the ITU-T recommendations, CTS
On
0 4 DCD On, CTS/DSR comply with the ITU-T recommendations
1 0 DCD follows modem carrier, DSR On, CTS On
1 1 DCD follows modem carrier, DSR follows off hook, CTS follows
DCD
1 2 DCD follows modem carrier, DSR and CTS both follow DCD set-
ting
13DCD follows modem carrier, DSR complies with the ITU-T recom-
mendations, CTS On
1 4 DCD follows modem carrier, CTS/DSR comply with the ITU-T
recommendations