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USRobotics
Command Reference
Data Command Set - 57
3.2.6 Data Compression Commands
This section contains parameters to condition modem use of standard ITU-T
V.42bis Data Compression Procedures.
+DS - Data Compression
This extended-format compound parameter controls the V.42bis data
compression function if provided in the modem. It accepts four numeric
subparameters:
Syntax
+DS=[<direction>[,<compr_neg>[,<max_dict>[,<max_string>]]]]
Defined Values
<direction> Specifies the desired direction(s) of operation of the data
compression function; from the DTE point of view.
0 Negotiated; no compression (V.42bis P0=0).
3 both directions, accept any direction (V.42bis P0=11). (Default.)
<compr_neg> Specifies whether or not the modem should continue to operate if
the desired result is not obtained.
0 Do not disconnect if V.42bis is not negotiated by the remote
modem as specified in <direction>.
<max_dict> Specifies the maximum number of dictionary entries (2048
entries) which should be negotiated (may be used by the DTE to
limit the codeword size transmitted, based on its knowledge of
the nature of the data to be transmitted).
<max_string> Specifies the maximum string length (32 bytes) to be negotiated
(V.42bis P2).
Reporting Current or Selected Values
Command: +DS?
Response: +DS: <direction>,<compr_neg>,<max_dict>,<max_string>
Example: +DS: 3,0,2048,32for the defaults and 2048 entry max dictionary.
Reporting Supported Range of Parameter Values
Command: +DS=?
Response: +DS: (<direction> range),(< compr_neg > range),(<max_dict>
range),(<max_string> range)