AT Command Reference
i-modul Modem 336 LL
Command
Description
AT&V<n>
Show the configurations
AT&V0
The active configuration of the modem, the saved user defaults and
the saved phone numbers 0 to 3 (the parameter 0 may be omitted)
are displayed.
AT&V1
Displays the diagnostic data of the last connection (connection
partner, reason for disconnect):
TERMINATION REASON:
Reason for disconnect.
E.g.: Connection termination via command (
ATH
: „
LOCAL RE-
QUEST
“)
LAST TX rate:
Last baud rate at the phone line in send direction,
prior to the termination.
HIGHEST TX rate:
Highest baud rate that was achieved at the
phone line in send direction, prior to the termination.
LAST RX rate:
Last baud rate at the phone line in receive direc-
tion, prior to the termination.
HIGHEST RX rate:
Highest baud rate that was achieved at the
phone line in receive direction, prior to the termination.
Note:
The data rates may vary if a fall forward, fall back or retrain
occurred during the connection. To impact the negotiated data rate,
use the command
AT+MS
.
PROTOCOL:
Display the used correction protocol. "
LAPM
" equals a
V.42 secured connection. For "
NONE
", the connection was not error
corrected (the error correction can be influenced with the com-
mand
AT\N
).
COMPRESSION:
Displays the used data compression method. The
example shows the used compression method V.42 bis (the com-
pression method can be set with the command
AT%C
).
LINE QUALITY:
Displays the quality of the data connection (devia-
tion from the eye diagram). Low values indicate a good line quality.
The line quality value must be evaluated differently depending on
the negotiated data rate.
Connections with more than 9600 baud will reach the value “000”
for good lines and should not have values of more than “010”.
For connections with 33600 baud good lines will have values be-
tween 010…030. Depending on the settings and the modulation
type a fall back or retrain is triggered if the line quality is too bad to
enable a new negotiation of the connection (if necessary with a
slower speed).
The value may vary also during a connection. A variation of 2 or 3
units in any direction is usual.
Rx LEVEL:
Displays the receive level (which is internally applied at
the modem chip) in –dBm. This request will be performed by the
internal controller in cyclic intervals automatically. High values in-
dicate a low input level; low values indicate a high input level. The
optimum receive levels range from approx. 012 to 028. To high
levels could cause distortions; too low levels will cause the line
noise to have a negative impact on the connection quality. The
value may vary also during a connection. A variation of 2 or 3 units
in any direction is usual.
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