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

Command:

+MR

Modulation Reporting Control

Description:

 

This extended-format numeric parameter controls whether or not the

 

 

extended-format +MCR:<carrier> and +MRR:<rate> intermediate result

 

 

codes are transmitted from the modem to the DTE. If enabled,

 

 

+MCR:<carrier> and +MRR:<rate> intermediate result codes represent the

 

 

current (negotiated or renegotiated) modulation <carrier> and <rate> that

 

 

are transmitted at the point during connect negotiation (handshaking) at

 

 

which the modem has determined which modulation and rate will be used,

 

 

i.e., before any Error Control or Data Compression reports are transmitted,

 

 

and before any final result code (e.g., CONNECT) is transmitted.

 

 

S95 bit 2 is reset to 0 for +MR=0 and is set to a 1 for +MR=1 or +MR=2.

 

 

The more recent setting of +MR or S95 bit 2, and the W command setting,

 

 

determines modulation result code reporting (see S95 Parameter and W

 

 

Command).

Default:

 

0

 

Defined Values:

 

+MR0

Disables reporting of modulation connection (+MCR: and +MRR:

 

 

 

are not transmitted).

 

 

+MR1

Enables reporting of modulation connection (+MCR: and +MRR:

 

 

 

are transmitted with TX rate, RX rate).

 

 

+MR2

Enables reporting of modulation connection (+MCR: and +MRR:

 

 

 

are transmitted with RX rate only).

Report Commands:

+MR?

Reports the current value.

 

 

+MR=? Reports supported range of parameter values:

Command:

%E

Enable/Disable Line Quality Monitor and Auto-Retrain or

 

 

Fallback/Fall Forward

Description:

 

Controls whether or not the modem will automatically monitor the line

 

 

quality and request a retrain (%E1) or fall back when line quality is

 

 

insufficient or fall forward when line quality is sufficient (%E2). The

 

 

parameter value, if valid, is written to S41 bits 2 and 6.

 

 

If enabled, the modem attempts to retrain for a maximum of 30 seconds.

 

 

Fallback/Fall Forward. When %E2 is active, the modem monitors the line

 

 

quality (EQM). When line quality is insufficient, the modem will initiate a

 

 

rate renegotiation to a lower speed within the V.34/V.32 bis/V.32 (RC336)

 

 

modulation speeds. The modem will keep falling back within the current

 

 

modulation if necessary until the speed reaches 2400 bps (V.34) or 4800

 

 

bps (V.32). Below this rate, the modem will only do retrains if EQM

 

 

thresholds are exceeded. If the EQM is sufficient for at least one minute,

 

 

the modem will initiate a rate renegotiation to a higher speed within the

 

 

current modulation speeds. The rate renegotiations will be done without a

 

 

retrain if a V.32bis connection is established.

 

 

Speeds attempted during fallback/fall forward are those shown to be

 

 

available in the rate sequences exchanged during the initial connection.

 

 

Fallback/fall forward is available in error correction and normal modes, but

 

 

not in direct mode or synchronous mode with external clocks.

Default:

 

2

 

Defined Values:

 

%E0

Disable line quality monitor and auto-retrain.

 

 

%E1

Enable line quality monitor and auto-retrain.

 

 

%E2

Enable line quality monitor and fallback/fall forward. (Default.)

Result Codes:

 

OK

 

Otherwise ERROR

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

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Multi-Tech Systems MT5600SMI-P92, MT5600SMI-XL34, MT5600SMI-PL92, MT5600SMI-92 manual +Mr, Modulation Reporting Control