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Chapter 4 - V.22bis Commands
Multi-Tech Systems, Inc. MT2456SMI-22 SocketModem Developer’s Guide 18
&R RTS/CTS Option
This selects how the modem controls CTS. CTS operation is modified if hardware flow control is selected (see &K
command). The parameter value, if valid, is written to S21 bit 2.
Syntax &R<value>
Defined Values
<value> Decimal number corresponding to the selected option.
0 In sync mode, CTS tracks the state of RTS; the RTS-to-CTS delay is defined by S26. In async mode, CTS is
normally ON and will turn OFF only if required by flow control.
1 In sync mode, CTS is always ON and RTS transitions are ignored. In async mode, CTS is normally ON and will
turn OFF only if required by flow control.
Result Codes OK <value> = 0 or 1
ERROR Otherwise
\G Modem-to-Modem Flow Control (XON/XOFF)
The modem enables or disables the generation or recognition of modem-to-modem XON/XOFF flow control
according to the parameter supplied. The parameter value, if valid, is written to S41 bit 3.
Due to the buffering system used in the modem, modem-to-modem flow control is normally disabled.
Syntax \G<value>
Defined Values
<value> Decimal number corresponding to the selected option.
0 Disables modem-to-modem XON/XOFF flow control. (Default.)
1 Enables modem-to-modem XON/XOFF flow control.
Result Codes OK <value> = 0 or 1
ERROR Otherwise
+IFC DTE-Modem Local Flow Control
This extended-format compound parameter controls the operation of local flow control between the DTE and the
modem during the data state when V.42 error control is used, or when fallback to non-error control mode is specified
to include buffering and flow control. It accepts two numeric subparameters.
Syntax +IFC=[<modem_by_DTE>[,<DTE_by_modem>]]
Defined Values
<modem_by_DTE> Specifies the method to be used by the DTE to control the flow of received data from the modem.
0 None.
1 XON/XOFF on transmitted data (XON/XOFF on transmit data); do not pass XON/XOFF characters to the
remote modem.
2 Circuit 133 (Ready for Receiving). (Default)
3 DC1/DC3 on circuit 103 (Transmitted Data) with DC1/DC3 characters being passed through to the remote
DCE in addition to being acted upon for local flow control
<DTE_by_modem> Specifies method to be used by the modem to control the flow of transmitted data from the DTE.
0 None.
1 XON/XOFF on received data.
2 CTS/RTS. (Default)
Reporting Current or Selected Values
Command: +IFC?
Response: +IFC: <modem_by_DTE>,<DTE_by_modem>
Example: +IFC: 2,2 For the defaults.
Reporting Supported Range of Parameter Values
Command: +IFC=?
Response: +IFC: (<modem_by_DTE> range),(<DTE_by_modem> range)
Example: +IFC: (0-3),(0-2)