S37 - Desired DCE Line Speed
Type
value
Value range
see list below, Default value: 0
Stored by &Wn
yes
Displayed by &V
yes
Description
A non-zero value of S37 selects the maximum (or only) carrier speed
that may negotiated during carrier handshake. S37 does not affect the speeds
that are valid during retrains or rate re-negotiation (see S109).
Note: When the value of S37 is 0, the effective value is the one
which selects the highest available line speed that does not exceed the
DTE speed. That is, the Nn and Bn commands behave as if this were the value
of S37.
During carrier handshake the modem attempts to connect at the highest supported
data rate that does not exceed the value entered in this register. This
applies to originated and answered calls; S37 sets the upper speed limit.
When V.34 modulation is used, it is possible to have different transmit
and receive line speeds. If the value of S37 is not zero and V.34 modulation
is used, then equal line speeds are forced. Lower speeds may be negotiated
if the appropriate Nn command is selected.
The following information describes the impact of S37on register S109:
a. If performing a V.32, V.32 bis, V.34, or V.FC handshake, the modem
connects only at speeds enabled by S109.
b. If Ans-A or Orig-A handshake behavior is selected (defined for
Nn command) and the speed indicated by S37 is one of the set covered by
S109, then the speed must match one of the speeds selected by S109 or when
the modem enters the handshake process and the modem sets S86 to value 16,
hangup, and sends the NO CARRIER result code.
c. If the speed and modulation combination selected by S37 and the
corresponding Bn command is not one of those affected by S109, then the
handshake proceeds normally. (See the description of S109
for the affected modulations.)
If the combination of S37, N0, and S109 would not allow a handshake to succeed
and the modem makes this determination before going off hook, then the following
actions may occur.
If the D command is given then the Go off hook until dial tone is detected
modem may... Hangup
Give the NO CARRIER result code
Set the value of S86 to 16.
If the A command is given or Go off hook for two seconds hangup
autoanswer is invoked by ringing then Give the NO CARRIER result code
the modem may... Set the value of S86 to 16.
If the DTE enters a reserved or The modem returns ERROR and does not change the value.
undefined value for S37...
Parameter Value Meanings:
Parameter Description
0 Use Last AT Speed
1 Reserved (75)
2 Reserved (110)
3 300
4 Reserved (600)
5 1200
6 2400
7 4800
8 7200
9 9600
10 12000
11 14400
26 16800
12 19200
33 21600
29 24000
34 26400
15 28800
104 31200
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