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Chapter 5 – AT Commands, S-Registers, and Result Codes
Multi-Tech Systems, Inc. SocketModem MT5600SMI Developer’s Guide 53
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