Multi-Tech Systems MT5600SMI-XL92 manual Data Compression Commands, Command +DS Data Compression

Chapter 5 – AT Commands, S-Registers, and Result Codes

Data Compression Commands

This section contains parameters to condition modem use of standard ITU-T V.42bis Data Compression Procedures.

Command: +DS	Data Compression
Description:	This extended-format compound parameter controls the V.42bis data
	compression function if provided in the modem. It accepts four numeric
	subparameters:
Defined Values:	<direction> Specifies the desired direction(s) of operation of the data
	compression function; from the DTE point of view.
		+DS0	Negotiated; no compression (V.42bis P0=0).
		+DS3	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.
		+DS0	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 code word 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).
Report Commands:	+DS?	Reports Current or Selected Values.
		Response: +DS:
		<direction>,<compr_neg>,<max_dict>,<max_string>
		Example: +DS:
		3,0,2048,32 for the defaults and 2048 entry max dictionary.
	+DS=?	Reports Supported Range of Parameter Values.
		Response: +DS:
		(<direction> range),(< compr_neg > range),
			(<max_dict> range),(<max_string> range)
		Example: +DS: (0,3),(0),(2048),(32)

Command: +DS44	V.44 Compression Select
Description:	This extended-format compound parameter controls the V.44 data
	compression function.
Defined Values:	<direction> Decimal number that specifies the desired direction(s) of
	operation of the data compression function; from the DTE point of view.
	+DS440	Negotiated, no compression.
	+DS441	Transmit only.
	+DS442	Receive only.
	+DS443 Both directions, accept any direction. (Default.)
	<compress_negotiation> Decimal number that specifies whether or not
	the modem should continue to operate if the desired result is not obtained.
	+DS440 Do not disconnect if V.44 is not negotiated by the remote
		DCE as specified in <direction>. (Default.)
	+DS441 Disconnect if V.44 is not negotiated by the remote DCE
		as specified in <direction>.
	<capability> Decimal number that specifies the use of stream method,
	packet method, multi-packet method.
	+DS440	Stream method. (Default.)
	+DS441	Packet method.
	+DS442 Multi-packet method.

Multi-Tech Systems, Inc. SocketModem MT5600SMI Developer’s Guide 60