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Chapter 4 - V.22bis Commands
Multi-Tech Systems, Inc. MT2456SMI-22 SocketModem Developer’s Guide 27
V.22bis Modulation Control Commands
+MS Modulation Selection
This extended-format compound parameter controls the manner of operation of the modulation capabilities in the
modem. It accepts six subparameters.
Syntax
+MS=[<carrier>[,<automode>[,<min_tx_rate>[,<max_tx_rate>[,<min_rx_rate>[,<max_rx_rate>]]]]]]
Table of +MS Command Supported Rates
Modulation <carrier> Possible (<min_rx_rate>, <min_rx_rate>, (<min_tx_rate>),
and <max_tx_rate>) Rates (bps)
Bell 103 B103 300
Bell 212 B212 1200 Rx/75 Tx or 75 Rx/1200 Tx
V.21 V21 300
V.22 V22 1200
V.22bis V22B 2400 or 1200
V.23 V23C 1200
Defined Values
<carrier> A string which specifies the preferred modem carrier to use in originating or answering a connection.
<carrier> values are strings of up to eight characters, consisting only of numeric digits and upper case
letters. <carrier> values for ITU standard modulations take the form: <letter><1-4 digits><other letters
as needed>.
<automode> A numeric value which enables or disables automatic modulation negotiation (e.g., V.22bis).
0 = Automode disabled.
1 = Automode enabled. (Default)
<min_rx_rate> and <max_rx_rate>
Numeric values which specify the lowest (<min_rx_rate>) and highest (<max_rx_rate>) rate at which
the modem may establish a receive connection. May be used to condition distinct limits for the receive
direction as distinct from the transmit direction. Values for this subparameter are decimal encoded, in
units of bit/s. Actual values will be limited to possible values corresponding to the entered <carrier> and
fall-back <carrier> as determined during operation. (Default = lowest (<min_rx_rate>) and highest
(<max_rx_rate>) rate supported by the selected carrier.)
<min_tx_rate> and <max_tx_rate>
Numeric values which specify the lowest (<min_tx_rate>) and highest (<max_tx_rate>) rate at which the
modem may establish a transmit connection. Non-zero values for this subparameter are decimal
encoded, in units of bit/s. Actual values will be limited to possible values corresponding to the entered
<carrier> and fall-back <carrier> as determined during operation. (Default = lowest (<min_tx_rate>) and
highest (<max_tx_rate>) rate supported by the selected carrier.)
Reporting Current or Selected Values
Command: +MS?
Response: +MS:<carrier>,<automode>,<min_tx_rate>, <max_tx_rate>,<min_rx_rate>,<max_rx_rate>
Example: +MS: V22B, 1,300,2400,300,2400
For default values. This example allows maximum system flexibility to determine optimal receive and transmit rates
during operation.
Reporting Supported Range of Parameter Values
Command: +MS=?
Response: +MS: (< carrier> range),(<automode> range),(<min_tx_rate> range),(<max_tx_rate> range),
(<min_rx_rate> range), (<max_rx_rate> range)
Example 1: +MS:(B103,B212,V21,V22,V22B,V23C),(0,1),(300-2400),(300-2400),(300-2400),(300-2400)
Result Code
OK Valid subparameter string
ERROR Otherwise