Chapter 3 – AT Commands, S-Registers, and Results Codes
Multi-Tech Systems, Inc. MT2834ZDX User's Guide 14
Command: &Rn Clear to Send Control
Values: n = 0, 1, or 2
Default: 1
Description: &R0 Let CTS state follow RTS state when on line.
&R1 Force CTS high (on).
&R2 Let CTS drop on disconnect for time set by S24, then go high again.
Command: &RAn Asymmetrical Bit Rate
Values: n = 0 or 1
Default: 0
Description: &RA0 Enable asymmetrical bit rate in V.34 mode.
&RA1 Disable asymmetrical bit rate in V.34 mode.
Command: &RDn Square Wave Ring Detect
Values: n = 0 or 1
Default: 1
Description: &RD0 Modem detects only sine wave rings.
&RD1 Modem detects both sine and square wave rings.
Command: &RFn CTS/RTS Interaction Control
Values: n = 0 or 1
Default: 1
Description: &RF0 Let CTS follow RTS.
&RF1 Let CTS act independently (use with &R).
Command: &RN Rate Negotiation
Values: n/a
Description: Forces the modem to perform a rate renegotiation while on line. You must escape to command
mode to issue this command.
Command: &RP Immediate Line Probe
Values: n/a
Description: Initiates a retrain that makes the processor read line probe information if %DP1 is selected. Valid
only when on line in V.34 mode.
Command: &RR Immediate Retrain
Values: n/a
Description: Forces the modem to perform an immediate retrain while on line. You must escape to command
mode to issue this command.
Command: $Rn Retransmit Count
Values: n = 0 or 1
Default: 0
Description: $R0 Disconnect after 50 retransmits of a data block.
$R1 Do not disconnect after 50 retransmits.
Command: Sr=n Set Register Value
Values: r = S-register number; n varies
Default: None
Description: Set value of register S r to value of n, where n is entered in decimal format.
Command: Sr? Read Register Value
Values: r = S-register number
Default: None
Description: Read value of register S r and display value in 3- digit decimal form.
Command: &Sn Data Set Ready Control
Values: n = 0, 1, or 2
Default: 1
Description: &S0 Force DSR high (on).
&S1 Let DSR follow CD.
&S2 DSR drops on disconnect, then goes high again. (Used by some CBX phone systems.)