T
ECHNICAL
Q
UICK
R
EFERENCE
167
Register Default
Function
S22
17
Stores the ASCII decimal code for the XON character.
S23
19
Stores the ASCII decimal code for the XOFF character.
S25
20
Sets the duration, in hundredths of a second, that DTR must be dropped so that the
modem doesn’t interpret a random glitch as a DTR loss. (Most users will want to
use the default; this register is useful for setting compatibility with older systems
running under older operating software.)
S27
0
Bit-mapped register setup. To set the register, see instructions for S13.
Bit
Value
Result
0
1
Enables ITU-T V.21 modulation at 300 bps for overseas calls; in
V.21 mode, the modem answers both overseas and domestic
(U.S. and Canada) calls, but only originates V.21 calls. (Default
Bell 103)
1
2
Enables unencoded (non-trellis coded) modulation in V.32 mode.
2
4
Disables V.32 modulation.
3
8
Disables 2100 Hz answer tone to allow two V.42 modems to
connect faster.
4
16
Enables V.23 fallback mode.
5
32
Disables V.32bis mode.
6
64
Disable V.42 selective reject.
