COURIER HIGH SPEED MODEMS
CHAPTER 5. INTERNAL CONTROLS
The commands explained in this chapter
are of two types. The first group
concerns default configurations, for
example, writing your own power-on
defaults to nonvolatile random access
memory (NVRAM). The remaining commands
are used to select the modem's local
operating characteristics, for a current
session or to include in your default
configuration. They include result
code, echoing, and other options.
NOTE: When you change a default setting
during a session, the modem retains that
setting until you do one of the
following.
ů Change the setting.
ů Issue the ATZ command to reset the
modem to its software defaults. If
DIP switch 10 is UP, the modem
resets to the defaults stored in
nonvolatile memory (NVRAM). If DIP
switch 10 is DOWN, the modem resets
to the factory settings stored in
read only memory (ROM).
ů Issue the AT&F command to load the
modem's factory settings.
ů Turn the modem off and power it on
again. At power-on, the modem
loads either the nonvolatile memory
defaults (DIP switch 10 UP) or the
factory settings (DIP switch 10
DOWN).
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SETTING/USING DEFAULTS
The modem's read only memory (ROM)
permanently stores the modem's factory
settings. The inclusion of nonvolatile
random access memory (NVRAM) allows you
to define your own configuration and
write the settings to NVRAM as your
power-on defaults.
WRITING DEFAULTS TO NVRAM (&W)
When you power on the Courier, it loads
the settings stored in NVRAM if DIP
switch 10 is UP (factory setting).
Until you write your own settings to
NVRAM, the defaults stored there are the
same as the permanent ROM factory
settings.
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You'll find a list of NVRAM options and
factory settings in Appendix B. You can
also display them by selecting option 5
of the I (inquiry) command:
ATI5 <Enter>
If you've sent the modem commands to
change settings throughout your session
and want to save your current configu-
ration, send just the &W command. The
current settings are saved.
AT&W <Enter>
You may also specify the entire
configuration in a single command string
that ends with the &W command. The
following example sets the modem for the
current session and stores the
configuration in NVRAM.
AT X4 &B1 &H1 M3 &W <Enter>
After sending a configuration to NVRAM,
you can change any setting just for the
current session, as in the following
example. The NVRAM configuration
remains intact.
ATX7 <Enter>
But if you want the new setting to be a
default, write it to NVRAM at the same
time, as in the following example. X7
is substituted for the X4 setting stored
earlier.
AT X7 &W <Enter>
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LOADING THE FACTORY DEFAULTS (&F)
If DIP switch 10 is DOWN, the factory
settings are loaded at power-on instead
of the NVRAM defaults. Factory settings
for the options that are stored in NVRAM
are in Appendix B.
If the NVRAM defaults are loaded at
power-on (DIP switch 10 UP) and you want
to load the factory defaults instead,
use the following command:
AT&F <Enter>
If NVRAM defaults are loaded, but you
want to view a screen listing of factory
defaults, first load them (&F), to make
them the
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COURIER HIGH SPEED MODEMS
current settings. Then include the I4
inquiry option to display a listing of
the newly current settings, as in the
following example.
AT&F I4 <Enter>
To restore your NVRAM defaults, use the
ATZ command described next. (DIP switch
10 must be UP.)
RESET (Z)
If you've changed several current
settings and want to reset to your
power-on defaults, type the following
command:
ATZ <Enter>
The modem reads its DIP switch settings
and resets either to its NVRAM defaults
(DIP switch 10 UP) or factory settings
(DIP switch 10 DOWN).
NOTE: Use the ATZ command also if
you've changed the position of DIP
switches 2-5, 7 or 9 while the modem is
on, so that the modem can read the new
setting. The only other way to initiate
a new setting for switches 2-5, 7 and 9
is to turn the modem off and on again.
STORING TELEPHONE NUMBERS (&Zn=s)
The modem stores up to four frequently
dialed phone numbers. Write the numbers
to NVRAM with the &Zn=s command, where n
is position 0 through 3, and s is the
phone-number string.
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The number-string may be up to 36
characters long, including any Dial
command options. The following example
includes the tone-dial (T) and wait for
a second dial tone (W) options of the
Dial command. The number is stored at
position 0, assumed because there is no
n parameter.
AT&Z=T9W5551234 <Enter>
The following example stores a long-
distance number at the second position.
We've added spaces for readability.
AT&Z2=1 516 555 1234 <Enter>
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The DSn command is used to dial a stored
number, as in this example to dial the
number stored at position 2:
ATDS2 <Enter>
NOTE: Do not include modem settings in
the &Z string. If the call requires a
special setting, insert it in the
command string before the DSn command.
In the following example, &M0 (no error
control) is inserted before the Dial
command:
AT&M0 DS2 <Enter>
The previous command establishes &M0 as
the current setting. To return to the
default error control mode, issue the
following command:
AT&M4 <Enter>
RESULT CODES
Four commands control the result codes
that the modem returns to the screen:
Vn Numeric/verbal response mode
Qn Display/suppress all result codes
&An Display/suppress additional
result code subsets
Xn Result code subset
Response Modes (Vn)
Result codes are sent to the screen in
either words (Verbal Mode) or numbers
(Numeric Mode). The Courier is factory
set to Verbal mode when it is powered on
(DIP switch 2 is UP). Use the Vn
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command to select verbal or numeric
result codes for a current session,
independently of the DIP switch setting.
At power-on and reset, the modem
operates according to the DIP switch
setting. The Vn command is not stored
in nonvolatile memory as a power-
on/reset default.
V0 Numeric Mode. Numeric result codes
are followed by a Carriage Return
but no Line Feed, as in the
following example, where a 3 is
returned (for NO CARRIER).
ATD1234567 <Enter>
becomes
3TD1234567 <Enter>
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V1 Verbal Mode. Verbal responses are
preceded and followed by a Carriage
Return and a Line Feed, as in the
following example:
ATD1234567 <Enter>
NO CARRIER
Quiet Mode (Qn)
Enable/suppress the display of result
codes. The Courier is shipped with DIP
switch 3 DOWN, to display result codes.
Use the Qn command to control the
display for a current session,
independently of the switch setting.
At power-on and reset, the modem
operates according to the DIP switch
setting. The Qn command is not stored
in nonvolatile memory as a power-
on/reset default.
Q0 Result codes are displayed.
Q1 Result codes are suppressed (made
quiet).
Q2 Result codes are suppressed only in
Answer mode.
Additional Result Code Subsets (&An)
Use this command to enable/disable one
of the following subsets of error
control, modulation or protocol result
codes.
&A0 ARQ (error control) codes are
disabled. This setting does not
affect an error-control connection;
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the modem returns the standard
CONNECT messages if result codes are
enabled.
&A1 ARQ codes are enabled. One of the
following results is sent to the
screen when a successful error
control connection is established.
Message 14 is displayed if the modem
is set to X0 and the connection is
at any rate from 1200 to 14.4K bps.
The remaining results indicate the
connection rate and require a
setting of X1 or higher.
14/CONNECT/ARQ 19/CONNECT 4800/ARQ
15/CONNECT 1200/ARQ 22/CONNECT
12000/ARQ
16/CONNECT 2400/ARQ 24/CONNECT
7200/ARQ
17/CONNECT 9600/ARQ 26/CONNECT
14400/ARQ
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&A2 HST/V32 modulation codes are
enabled. This option is included
for users of HST Dual Standard
modems. If your software cannot
handle the added modulation
information, select &A1 or &A0.
23/CONNECT 9600/HST or 33/CONNECT
9600/V32
27/CONNECT 9600/ARQ/HST or 37/CON
NECT 9600/ARQ/V32
28/CONNECT 4800/HST or 38/CONNECT
4800/V32
29/CONNECT 4800/ARQ/HST or 39/CON
NECT 4800/ARQ/V32
30/CONNECT 7200/HST or 40/CONNECT
7200/V32
34/CONNECT 7200/ARQ/HST or 44/CON
NECT 7200/ARQ/V32
31/CONNECT 12000/HST or 41/CONNECT
12000/V32
32/CONNECT 12000/ARQ/HST or 42/CON
NECT 12000/ARQ/V32
35/CONNECT 14400/HST or 45/CONNECT
14400/V32
36/CONNECT 14400/ARQ/HST or 46/CON
NECT 14400/ARQ/V32
&A3 Protocol codes are enabled. Error
control protocols reported are: HST,
LAPM, or MNP. When the call is not
under one of those protocols (and
ARQ is not included in the result
code), the modem reports either
SYNC, indicating a synchronous
connection, or NONE, for no
protocol.
If the modems are using data
compression, the type of
compression, V42BIS or MNP5, is
added to the result code. In the
first of the following examples, the
modems negotiated error control for
the call (ARQ), used HST modulation,
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COURIER HIGH SPEED MODEMS
are using HST error control
protocol, and are using V.42 bis
compression.
CONNECT 14400/ARQ/HST/HST/V42BIS [
or MNP5]
CONNECT 14400/ARQ/V32/LAPM/V42BIS [
or MNP/MNP5]
CONNECT 9600/SYNC
CONNECT 2400/ARQ/MNP/MNP5 [or
LAPM/V42BIS]
CONNECT 2400/NONE
NOTE: Although these codes will
return numeric identifiers, they are
the same numeric identifiers used
for &A2 result codes. If the modem
is in Numeric Mode (V0) and set to
&A3, you will not be able to
differentiate between &A2 and &A3
result codes. &A3 result codes may
not be compatible with some
software.
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COURIER HIGH SPEED MODEMS
Result Code Sets (Xn)
You have eight options, 0 through 7, for
selecting the result code subset best
suited to your applications.
X0 Basic subset, returns the first five
codes (0-4) in the following table.
X1 Extended subset, codes 0-5, 10, 13
and 18. Default. This set adds
rate-specific CONNECT messages to
the Basic set.
X2-7 These options include the X1
subset and offer advanced call-
progress codes and functions.
Setting
Result Codes X0 X1 X2 X3 X4
X5 X6 X7
0/OK + + + + + + + +
1/CONNECT + + + + + + + +
2/RING + + + + + + + +
3/NO CARRIER + + + + + + + +
4/ERROR + + + + + + + +
5/CONNECT 1200 + + + + + + +
6/NO DIAL TONE + + + +
7/BUSY + + + + +
8/NO ANSWER + + + + +
9/RESERVED
10/CONNECT 2400 + + + + + + +
11/RINGING + + +
12/VOICE + +
13/CONNECT 9600 + + + + + + +
18/CONNECT 4800 + + + + + + +
20/CONNECT 7200 + + + + + + +
21/CONNECT 12000 + + + + + + +
25/CONNECT 14400 + + + + + + +
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Functions
Adaptive Dialing + + + + +
+
Wait for 2nd Dial Tone (W) +
+ + + +
Wait for Answer (@) + + + +
+
Fast Dial + + + +
Table 5-1. Result Code Options
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NOTE: Additional messages indicate an
error-control connection and the
modulation for a call. See Additional
Result Code Subsets (&An), earlier in
this chapter.
Result Code Meaning
0/OK Command has been executed
1/CONNECT Connection established with
another modem; if set to X0,
connection may be at 300, 1200,
2400 or 9600 bps; if X1 or
higher, connection is at 300 bps
2/RING Incoming ring detected
3/NO CARRIER Carrier detect has failed or
carrier has been dropped due to
disconnect
4/ERROR Command is invalid
5/CONNECT 1200 Connection established with
another modem at 1200 bps
6/NO DIAL TONE Dial tone not detected during
the normal 2 seconds, set in
Register S6
7/BUSY Busy signal detect; modem hangs
up
8/NO ANSWER After waiting 5 seconds for an
answer, modem hangs up; returned
instead of NO CARRIER when the @
option is used
10/CONNECT 2400 Connection established
with another modem at 2400 bps
11/RINGING The modem has dialed; remote
phone line is ringing
12/VOICE Voice answer at remote site;
modem hangs up
13/CONNECT 9600 Connection established at
reported rate. Same meaning for
results of 4800 (18), 7200 (20),
12K (21) and 14.4K (25).
Adaptive Dialing The modem attempts to use
Touch-Tone dialing and, if that
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doesn't work on the line, reverts
to rotary dialing.
Wait for Another The modem continues
dialing as soon as it detects
Dial Tone (W) another dial tone. See
the dial options in Chapter 6.
Wait for an The modem continues dialing when
it detects 5
Answer (@) seconds of silence on the line.
See the dial options in Chapter
6.
Fast Dial The modem dials immediately on
dial-tone detect, instead of
waiting the normal 2 seconds set
in Register S6.
Table 5-2. Result Code Definitions
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LOCAL ECHO
Local echo is the display of what you
type at the keyboard and data the
Courier transmits to another modem. The
En command controls the display of your
typed commands, when the modem is in
Command Mode. The Fn command applies to
when the modem is online to another
system.
Command Mode Local Echo (En)
The En command enables/disables the
display of your typed commands. If
double characters appear on the screen,
both the modem's local echo and your
software's local echo are on.
The Courier is shipped with DIP switch 4
UP, enabling local echo. The En command
controls the local echo for a current
session, independently of the switch
setting. At power-on and reset, the
modem operates according to the DIP
switch setting. The En command is not
stored in nonvolatile memory as a power-
on/reset default.
E0 Command Mode echo OFF. The modem
does not display keyboard commands.
E1 Command Mode echo ON.
Online Local Echo (Fn)
This command causes the modem to display
a copy of the data it is transmitting to
another system. Many systems, however,
return a copy of received data, which is
called a remote echo. If the modem's
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online echo is ON and there is also
remote echoing, double characters appear
on the screen.
In some microcomputer documentation, the
term duplex is applied to local online
echoing, although the term is not
technically accurate.
F0 Online echo ON. Sometimes called
half duplex. As the modem transmits
data to a remote system, it also
sends a copy of the data to the
screen.
F1 Online echo OFF. Sometimes called
full duplex. Default.
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THE AUDIO MONITOR
The modem's speaker enables you to
monitor the dial-connect process. There
are several ways to make use of this
feature. After the Courier dials a
number, it waits 60 seconds for a high-
pitched answer tone from the other
modem, immediately followed by data
signals, called a carrier. These
signals must occur before a data link is
established.
At the default X1 setting, if someone
answers the phone, or if the line is
busy, the modem sends the message NO
CARRIER to your screen after 60 seconds.
If you listen to the speaker, you can
respond immediately instead of waiting
for the modem to time out.
For example, if you hear someone
answering the call, you can pick up the
phone, if it's attached to the modem,
and talk to the person. Or you can
cancel the call by pressing any key on
the keyboard. In the same way, you can
cancel a call when you hear a busy
signal.
You can also hear if dialing is
proceeding too quickly for the system.
Terminate the call (press any key) and
retype the Dial command, but insert a
comma (,) or a couple of slashes (/), to
have the modem during the dialing
process.
SPEAKER CONTROL (Mn)
This command disables the speaker
entirely or sets the speaker to monitor
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different segments of the dial-connect
sequence.
M0 This setting disables the speaker
entirely so that you don't hear the
modem go off hook, dial, etc.
M1 The speaker is ON until Carrier
Detect. Default. You can monitor
call progress until the Courier
detects the remote modem's carrier
signals, or until the 60-second
timeout and result code display. At
Carrier Detect, the modem discon-
nects the speaker and data
transmission sounds are suppressed.
M2 The speaker is ON continuously,
including during data transmission.
M3 The speaker doesn't go ON until
after the last digit is dialed, then
goes OFF at Carrier Detect.
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MODEM CLOCK USAGE (Kn)
The modem clock is used as a call-
duration timer or as a real-time clock.
Used in conjunction with the In
(Inquiry) command, the modem returns the
duration of the last call in hours,
minutes, and seconds or the actual time.
K0 Call-Duration Mode. Default. The
modem times each call from CONNECT
to NO CARRIER, and stores the infor-
mation until the next connection or
when the modem is reset. At ATI3
<Enter>, the modem displays the
call's duration. If you wish, you
can maintain a call log by printing
this information after each call.
K1 Real-Time Mode. The clock operates
as a real-time clock regardless of
the presence of a carrier. Set the
clock (in military time) by
specifying the hour, minutes, and
seconds as in the following example,
which sets the clock at the real
time of 1:30 p.m.
ATI3=13:30:00 K1 <Enter>
At ATI3, the modem displays the real
time. You'll need to set the clock
each time you power on the modem,
but the clock is not affected by the
reset command, ATZ.
TRANSMITTER ENABLE/DISABLE (Cn)
If an additional terminal and modem
share the phone line for monitoring
purposes, the second modem is placed in
Receive Only state by disabling its
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transmitter. Use this feature only at
1200 or 300 bps.
C0 Transmitter disabled. Modem is set
to Receive Only.
C1 Transmitter enabled. Default.
BREAK HANDLING (&Yn)
This command allows you to send a break
to abort data transfer without
disconnecting from the phone link. The
following options are available.
&Y0 Destructive, no Break transmitted:
the modem clears the data from its
transmit buffer (all data is lost)
but does not transmit the Break to
the remote modem.
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&Y1 Destructive, expedited: the modem
clears the buffer and immediately
sends a Break to the remote modem.
Default.
&Y2 Nondestructive, expedited: the
modem retains data in the transmit
buffer, but immediately sends a
Break to the remote modem.
&Y3 Nondestructive, unexpedited (send
Break in sequence): the modem
transmits any buffer data received
before the Break, sends the Break,
and then sends any subsequent input
from the DTE.
NOTE: If the call is under MNP5 data
compression, destructive Breaks cause
both modems to reset their data
compression tables. When transmission
resumes, the modems build new tables,
and the result is lower than normal
throughput.
S-REGISTERS
The S-Registers are used to set various
timing parameters, redefinition of
selected ASCII characters, and other
configuration options. The defaults
reflect typical requirements.
A detailed summary of the S-register
functions is in Appendix B. A less
detailed summary is in the Quick-
Reference card.
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