AT Commands F-71
Register Descriptions
S21 Bit Mapped Register
1.See also register :T15 description.
Bit
Position
Function
Decimal Value
0
Telco Jack
0 default
1 not supported
1,21
CTS/RTS
synchronous 0
on hook: CTS follows RTS
off hook: CTS Off until connection
After connection:
CTS Off in response to On-to-Off RTS
transition;
CTS On in response to Off-to-On RTS
transition after delay specified in S26
(&R0)
1 on hook: CTS On;
off hook
: CTS Off until connection.
After connection
: CTS On for
duration of carrier signal (&R1)
2 ITU-T V.13 emulates half-duplex
over a full duplex line (&R2)
3,4
DTR
0 Ignores DTR (&D0)
1 On-to-Off DTR transition: modem
enters command state (&D1)
2 On-to-Off DTR transition: modem
goes on hook (&D2)
3 On-to-Off DTR transition: modem
resets (&D3)
5
DCD
0 DCD always On
1 DCD On indicates data carrier is
present or indicates DCD On except
momentarily at disconnect
6
not used
7
long space
disconnect
0 off (Y0)
1 on (Y1)
