US Robotics 56K USB Modem User Manual page 109

S38—56K Downstream Rate
Once a connection type* (V.90) is determined, use register S38 to force a particular downstream rate. A
value of zero disables both connection types and allows a more reliable V.34 connection. The default value
of one allows the modem to select the downstream rate automatically. Other values of S38 force the
downstream rate, with fallback to V.34 if unsuccessful at the configured rate.
Range: 0—23.
• Default: 1.
Table 219. Register S38 Values
Value INF File's HKR Value
0 —
1 —
2 60,6d,00,00
3 95,72,00,00
4 CA,77,00,00
5 —
6 35,82,00,00
7 6A,87,00,00
8 —
9 D5,91,00,00
10 0A,97,00,00
11 —
12 75,A1,00,00
13 AA,A6,00,00
14 —
15 15,B1,00,00
16 4A,B6,00,00
17 —
18 B5,C0,00,00
19 EA,C5,00,00
20 —
21 55,D0,00,00
22 8A,D5,00,00
23 —
* Refer to register S109 to determine connection type.
The number of robbed-bit signaling (RBS) frames detected decreases the true DCE rate as shown in Table
220.
Table 220. RBS Frames Detected
RBS Links Rate Hit
0 0 kbits/s
1 2 kbits/s
2 4 kbits/s
3 4 kbits/s
For example, if S38 = 10 and there are three RBS links, the K56flex downstream rate is 44 kbits/s
V.90 Downstream Rate
V.90 disabled
Automatic rate selection (default)
28 kbits/s
29.333 kbits/s
30.666 kbits/s
32 kbits/s
33.333 kbits/s
34.666 kbits/s
36 kbits/s
37.333 kbits/s
38.666 kbits/s
40 kbits/s
41.333 kbits/s
42.666 kbits/s
44 kbits/s
45.333 kbits/s
46.666 kbits/s
48 kbits/s
49.333 kbits/s
50.666 kbits/s
52 kbits/s
53.333 kbits/s
54.666 kbits/s
56 kbits/s
RBS Links
4 6 kbits/s
5 8 kbits/s
6 8 kbits/s
— —
Rate Hit
Command Reference - 103
56K USB Modem
User Guide