ARC CDL-900 User manual

ARC CDLARC CDL--900900
Cellular modem
and Transceiver
ARC ElectronicsARC Electronics
18001800--926926--0226 / 2810226 / 281--392392--63336333

Feb 21, 2001 Cellular Data Link CDL 900
Point-to-Point Wireless Access Solution.
Table of Contents
1) Product Overview 2
2) Registering the CDL 900 3
3) Starting and Configuring the CDL 900 3
4) Theory Of Operation 4
5) Supported AT Commands 7
6) Quick trouble-shooting hints 8
7) Frequently Asked Questions (FAQs) 8

Product Overview
The Cellular Data Link 900, CDL 900, is a self-contained unit that uses the Advanced
Mobile Phone System (AMPS) cellular network for data transmission. AMPS is the
cellular system used in North America, Latin America, Australia, New Zealand and parts
of Africa. AMPS system is not compatible with the GSM system used in Europe and Asia.
The CDL 900 has an RS232 interface and supports the popular AT command set
normally associated with modems.
CDL 900 Features
The CDL 900 provides the following features:
♦Uses AMPS Switched Circuit Cellular network for data transmission
♦User friendly modem AT command set
♦Standard RS 232 serial interface
♦Choice of Hardware or Software Flow Control
♦Incorporates “Quiet Mode” (explained later) thereby enabling communication with
“non-intelligent” systems
Sample Application Areas
Although any application requiring Data Communications can use the CDL 900, the
following are the areas where our OEM customers are using the CDL 900.
♦Packet Data Radio
♦SCADA and Telemetry Systems
♦Remote gas/water/electric meter readings.
♦Factory Automation systems
♦Vending Machines
Specifications
♦Air Speed upto 9600 bps
♦DTE Rate 300, 1200, 2400, 9600, 19200
57600 bps (switch selectable)
♦Data Compression & Error Detection MNP2-5, V42, V42bis, MNP 10
♦Transmit Power 0.6 watts
♦Power Supply 10-18 Volts DC @ 600 ma
(24/48 volts power supply optional)
♦Interface RS 232 Asynchronous
♦Signals supported TXD, RXD, CD, DSR, RTS, CTS, RI,
DTR
♦Operating Temperature Range 0 to 70 deg C ( -10 to + 85 optional )
♦Custom Configurations and Options Yes
Packing List
Make sure that the following items are included with this package. If anything is missing,
please contact your supplier.
♦CDL 900 unit with radio included
♦Antenna
♦RS 232 cable
♦This Cellular Data Link 900 User Guide

Before you use the CDL 900 unit, you need the following:
♦A host PC with terminal program like Hyper terminal, Procomm etc
♦Mobile Identification Number (MIN) provided by your Cellular service provider. MIN is
your cellular phone number.
♦System ID (SID) information (from your cellular service provider) SID uniquely
identifies your cellular service provider.
Registering the CDL 900 Unit
To register your CDL 900 unit, do the following:
1. Contact your cellular service provider
2. Provide the cellular operator with the ESN (Electronic Serial Number) number located
on the label at the top of your unit.
3. Inform the cellular operator that the unit is an AMPS Analog unit with a power rating of
class 3 (power 600 mw).
The cellular operator will register your unit and provide you the following information:
a) MIN (Mobile Number) Number:
b) System preference: A or B
c) SID (System ID)
It is recommended that you note the MIN and SID on the label at the top of the unit.
Starting and configuring the CDl 900 unit
The CDL900 is configured as a DCE (e.g. modem). It communicates with a PC through
the serial (RS 232) port.
Antenna
TR TX MR RX PWR
3.5”
DIP Switch
Power Supply DB 9 (F)
6.0”
TR = Terminal Ready TX = Transmit Data MR = Modem Ready
RX = Receive Data PWR = Power

Starting the CDL 900 Unit
To start the CDL 900 unit, perform the following steps:
1) Connect the power supply. After a few seconds, the PWR light should turn ON.
After approximately 10 seconds, the MR light should turn ON. The unit is now
ready for operation.
2) Connect the CDL 900 to the PC with the RS 232 cable provided.
3) Connect the Antenna to connector at the top left of the CDL 900.
4) Click the Hyper Terminal icon on the PC. Or select
Start>Programs>Accessories>Hyper Terminal>Hyperterm.exe
The Connection Description Dialog Box opens.
5) In the name field, enter CDL 900 and click OK.
The Connect To dialog box is now active.
6) Select Connect Using and then select the COM Port the CDL 900 is connected
to. For example, if the CDL 900 is on COM 2, choose “Direct to Com2” and click
OK.
7) The COM2 Properties dialog box now opens. Select the following:
a) Bits per second to match the DIP switch settings on the CDL 900
b) Data Bits: 8
c) Parity: None
d) Stop Bits: 1
e) Flow Control based on the CDL 900 switch settings.
f) Click OK.
8) Select Call>Disconnect
9) Select Call>Connect
The TR (Terminal Ready) light on the CDL 900 should turn ON. If it does NOT
turn ON, please check that the CDL 900 is connected to the right serial port on
the PC.
10) Select File>Properties>Settings>ASCII setup
11) Check the following:
a) In the ASCII Sending field, check Echo typed characters locally
b) In the ASCII receiving field, check Append line feeds to incoming line ends
and Wrap lines that exceed terminal width.
12) Click OK twice.
13) Select Call>disconnect
14) Select Call>connect
15) Select File>Save
Configuring the CDL 900
To configure the CDL 900, perform the following steps:
16) Enter AT+TEST<CR>. The unit responds OK.
a) Enter AT+MIN=< allocated_MIN ><CR> The unit responds OK.
b) Enter AT+SID=< allocated_SID ><CR> The unit responds OK
c) Enter AT+SYS=02 <CR> (SID will determine preferred system, also
called normal mode)
=00 <CR> (will select system B only)
=01 <CR> (will select system A only)
Check with your provider as to which is the recommended system.
The CDL 900 does NOT have to configured every-time. The above information is
stored in the unit’s non-volatile memory.
17) Enter AT+MODE=02<CR> The unit is now set for data mode.

18) Enter AT+SER <CR> The unit responds with SERVICE AVAILABLE.
Using the CDL 900 to communicate
To use the CDL 900 to communicate with a modem, perform the following steps:
1) Enter ATDT XXXX <CR>
XXXX is the phone number of the modem you are calling. After approximately 30
seconds, the CDL 900 responds with CONNECT message.
2) Type “ Hello how are you”
The party you called should see the message on their terminal screen.
3) Ask the called party to type a message and you should see that on your terminal
screen.
4) Enter the Escape sequence +++
The modem responds OK.
5) Enter ATH0<CR>
The CDL 900 responds “No Carrier “ indicating that the connection is
terminated.
6) Ask the remote party to dial you MIN number.
CDL 900 responds with CONNECT message after approximately 30 seconds.
7) Repeat steps 2 to 5.
Theory of Operation
The CDL-900 is always in one of the two states:
•Command state
•Online state
This section describes the two states.
Command State
The CDL 900 assumes the Command state when it is turned ON. In this state, you can
configure the unit for a particular application. In the Command State, all inputs from the
PC are treated as commands.
Command guidelines
Command line is a string of characters sent from the DTE (example PC) when the unit is
in the Command state. All commands must adhere to the following guidelines
•Command lines must have a prefix , a body and a terminator.
•Command lines must begin with a character sequence AT.
•Command Lines must end with Carriage return (CR).
•Either all upper case or all lower case characters must be used.
•Each command must be entered separately.
•Command buffer is 40 characters.
Note: Commands entered incorrectly or with out-of-range parameters will result in
ERROR message. Commands entered correctly will result in OK message.
Result Codes
Result Codes refer to the responses of the CDL 900 unit to a command.
Unless the CDL 900 has been programmed to be in the Quiet mode (explained later in
the AT command section), the unit will respond each time a command is issued. The
default mode of the CDL 900 is the Verbose mode. The responses in verbose mode are
characters.

Using AT commands, the modem can be put into terse (non-verbose) mode. The
responses in non-verbose mode are numerical digits.
Various modem responses are shown below:
Examples of CDL responses:
Response in Response in Meaning
Terse Mode Verbose Mode
0OK Command executed without errors.
1CONNECT Connection at 300 bps
2RING Ringing signal detected
3NO CARRIER Carrier lost or never present
4ERROR Invalid command
5CONNECT 1200 Connection at 1200 bps
6NO DIALTONE Cellular service not available
7Busy Called party on-line
8No Answer
9Connect 0600
10 Connect 2400
11 Connect 4800
12 Connect 9600
13 Connect 7200
66 Compression class 5 Connection established
MNP-5
67 Compression V42bis
68 Not used
69 Compression none
76 Protocol: none
77 Protocol: LAPM
99 SERVICE UNAVAILABLE Cellular service not available
100 SERVICE AVAILABLE Unit ready for
communication
On-line state
In online state, input(s) from the PC is treated as data to be shipped over the airwaves,
and input(s) from the airwaves is treated as received data from the remote end.
The CDL 900 is in online state in one of the two conditions:
a) CDL 900 dials out and a successful connection is established.
b) CDL 900 answers an incoming call and a successful connection is established.
When the CDL 900 is in online state, all serial data presented to the radio is transmitted
over the air.
You should NOT change communication parameters (e.g. baud rate) in this mode.
To go back to Command State, Escape Sequence (described in this section) is required.
Transitioning from Online state to Command state (Escape sequence)
The sequence of characters to transition from Online State to the Command State is
called the escape sequence.
For CDL 900, he escape sequence is +++
The timing interval between the + signs must be between 250 msecs and 750 msecs.
When the CDL 900 receives a valid escape sequence, the modem will enter Command
State and respond with OK.

Supported AT commands
This section describes the basic Attention (AT) commands used to configure the CDL
900. These commands are a subset of the commands used in typical high-speed
modems.
A command line is a string of characters sent from the DTE (e.g. a PC) while the modem
is in Command State. A command line has a prefix, a body and a terminator. Each
command line must begin with a character sequence AT and must terminate with a
carriage return.
The Radio starts the processing of commands only after AT string sequence is received.
Commands entered with out of range parameters will result in ERROR message.
Correct commands will result in OK message in verbose mode, and 0 in terse mode.
Supported AT commands:
Command Action Note
1) ATZ<CR> Resets the modem.
The unit responds with OK messages
2) ATO<CR> Go on line. This is done after
the state of the unit is changed from
on-line to command state.
ATO then puts the unit back into
online state.
3) ATDT XXXX <CR> Cell modem dials out.
XXXX is the phone number
4) AT+TEST <CR> Puts the unit in test mode
The commands AT+SYS, AT+MIN, AT+SID and AT+ID can be entered only when
the unit is in Test Mode.
5) AT+SYS=xx<CR> Sets system preference.
SYS =00 sets the unit for system B only
SYS =01 sets the unit for system A only
SYS =02 is for normal mode. SID determines preferred system
SYS =03 is for home use only
6) AT+RSSI<CR> Indicates the Received Signal
Strength. Should be > -100 dbm for
reliable communication.
7) AT+SER <CR> Indicates if service is available or not
8) AT+MIN=XXXXX<CR> Sets the MIN number. The modem responds OK
9) AT+SID=XXXX<CR> Sets SID. Modem responds OK
10) AT+ID?<CR> Displays ESN, MIN, SID,
System Preference information.
Note: MIN, ESN, SID information are stored in the non-volatile memory of the cell-
modem. These do not have to be entered every-time on power-up.
To exit test mode, enter AT+MODE=02<CR>
11) ATQ1<CR> Unit does not respond with OK or non-verbose
messages. This is ideal for in situations where the
Data Link is connected to “non-intelligent” host.
This mode is also called Quiet Mode.

12) ATQ1&W&W1 Q1 instruction stored in non-volatile memory.
13) AT&V<CR> Displays settings of the cell modem
14) ATI3<CR> Displays Software Revision #
15) ATH0 Modem disconnects and initializes
16) ATV0 Unit responds in terse mode. Results code
Displayed as digits
17) ATV0&W&W1 Above command stored in non-volatile memory.
On power-up, the modem will be in terse mode.
18) ATV1 Unit responds in verbose mode. Results codes
are displayed as messages.
19) ATV1&W&W1 Above command stored in non-volatile memory.
On power-up, the modem will be in verbose mode.
20) ATS0 Default is 0. If 0, then the unit will not answer
incoming call. Please use ATS0=1&w&w1 to have
the unit answer incoming calls.
Escape Sequence:
When the modem is on-line state, it is possible to break the data transmission/reception.
This is achieved by sending a sequence of three ASCII characters. For ease of use, the
default character is +.
The Radio will respond with OK on detection of valid escape sequence.
21) +++ Escape sequence OK
Basic Troubleshooting :
1) If the unit draws too much power. Please ensure that the correct power supply is
used and correctly wired.
2) If dialing out is repeatedly unsuccessful and modem gives the message “NO
DIALTONE ”, please check if service is available.
3) If the unit never connects on dialing out, please ensure that the ESN (Electronic
Serial Number) and the MIN numbers are right.
4) Please check RSSI level. If low (lower than –95 dbm), placing the antenna vertical
will help.
5) If remote landline modem connection drops frequently, please have the calling
party set S7=60 & S10 register to 200. This will make the modem more tolerant of
noise hits. This can be done as follows:
ATS0=1S7=60S10=200&W&W1<CR>
6) If for some reason, the CDL 900 unit is not responding, please try the command
AT&F&W&W1 <CR>
Whenever the command AT&F&W&W1 is issued, then you must do the following
ATS0=1\N2+MS=11,1,1200,2400&W&W1 <CR>
AT-SEC=1,15&W&W1 <CR>
7) If that also fails, power down the unit and power it up again.
8) Please read next section on FAQs.
Frequently Asked Questions (FAQs)
1) Question: What is the flow control method recommended?

Answer: If the host is a PC, Hardware flow control is recommended.
However, in most control instrumentation, either software or no
flow control is called for.
2) Question: How do I disable any flow control?
Answer: Simply disable both the Hardware and software control switch
settings. This is not recommended for large file transfers.
3) Question: I need to connect the Cellular Data Link to a machine which
does not understand your messages. All it needs is data. Which
configuration is recommended?
Answer: Please use the ATQ1&w&w1<CR> command.
4) Question: Have you experienced that fact that communication with certain
brands of modems is unreliable?
Yes. And more so with generic brand which tend to throw hot
signals (i.e strong signal levels) on the line. This causes the
Cellular service to over-modulate which leads to distortions and
results in unreliable connections.
5) Question: What is the solution then?
Answer: We recommend that you use modems that support MNP-10
and also allow transmit level to be reduced to between –15 dbm.
and –20 dbm. Rockwell based modem designs generally meet
these requirements.
For Rockwell based modems, please try the following commands
on the land line modem:
AT-SEC=1,18 <CR>. This will enable MNP 10 and set transmit
level to –18 dbm.
AT+MS=11,1,1200,4800&W&W1<CR>. Sets the modem to
communicate between 1200 and 4800 bps.
ATS91=15 <CR>.
6) Question: Is there any simple way to avoid frequent loss of connection?
Answer: Please program the CDL 900 as follows
AT+MS=11,1,1200,1200&W&W1<CR>
This will force the CDL 900 to connect only at 1200 bps.
7) Question: Can IDC provide a landline modem I can use?
Answer: Yes.
8) Question: What initialization string is recommended to communicate with a
non MNP modem?
9) Answer: Connection with non MNP landline modems is not recommended.
10) Question: My requirement(s) are totally unique. Can I count on IDC to help?
Answer: Absolutely.
11) Question: Is there any recommended init string for various land line
modems?
Answer: the following have been tried with great success:
a) For US Robotics / 3 Com modems:
ATS10=200&A3&B1&N2&U2&W&W1 <CR>
b) For Rockwell chip set based land-line modems 33600 and lower
AT%E2\N2S7=60S10=200+MS=11,1,1200,4800&w&w1 <CR>
c) For most other brands:
ATN0S37=6S10=200&w&w1 <CR>

For Rockwell chip set based land-line modems 56K V90 models
AT%E2\N2S10=200S7=60+MS=V34,1,1200,2400,1200,2400 <CR>
Speed and Flow Control Switch Settings
To select a given speed put the switch for that speed down (the on state) -use only
one switch to select that speed.
For Hardware flow control (H/W) use Switch #7-down is the on state
Software Flow Control (S/W) use Switch #8-down is the on state

SUMMARY OF THE ROCKWELL "AT" COMMAND SET
To communicate using the modem, use an asynchronous communication program. The command
set for the modems is compatible with the Hayes command set.
The modem is controlled and configured by the AT (attention command). Each command consists
of the following elements (with the exception of the A/and the +++ command that will be discussed
later). A command is not entered until a carriage return <ENTER> is entered. Spaces entered are
ignored. For example, to enter the command `Answer', type ATA and <ENTER>.
Some commands do not have parameters. Any missing parameters in a command is assigned the
value zero, which may be a valid parameter for the command. The sequence followed by AT
command causes the modem to enter a command state. That is, AT without a command serves as
a wake up code and an "OK" appears on the screen. The modem queues the commands in a 40-
character command line. The command line begins with AT and can have several commands. A
separator is not required between the commands.
When a carriage return is received, the commands are performed in the order in which they are
sent to the modem. If more than 40 characters are sent to the modem, an error occurs and all
commands must be re-entered.
A common configuration for a remote modem is to answer the call and hang up on
loss of carrier. To do this the RS232 interface has to be set for the correct
configuration.
Option if the Computer uses pins 2, 3, & 7 only -Set the AT commands as follows
ATS0=1 (modem will answer on the first ring)
AT&D0 (modem will ignore DTR)
factory default is AT&D1 which allows the modem to answer only if
DTR is high.
AT&V to check the state of the "S" registers use AT&V
AT&W0 Don't forget to burn the new codes into E-PROM by AT&W0
To see your typing you made need to turn on E1 for the modem to echo back responses. Some
software doe not like it's data echoed back so don't forget to check E1/E0 if your software is acting
strange.
Note: you may want to put the modem into a quiet mode -ATQ1 (ATQ0 is the default) modem does not send result codes -
which can confuse the computer.
A good configuration for a dumb mode operation is
AT&F&C1&D0E0Q1S0=1&W0AT&F&C1&D0E0Q1S0=1&W0

BASIC AT COMMANDS for the 14.4 & 33.6 MODEM MODULE...
Command Function
A/ Re-execute command.
AGo off-hook and attempt to answer a call.
B0 Select V.22 connection at 1200 bps.
B1 Select Bell 212A connection at 1200 bps.
C1 Return OK message.
Dn Dial modifier.
E0 Turn off command echo.
E1 Turn on command echo.
F0 Select auto-detect mode (equivalent to N1).
F1 Select V.21 or Bell 103.
F2 Reserved.
F3 Select V.23 line modulation.
F4 Select V.22 or Bell 212A 1200 bps line speed.
F5 Select V.22 bis line modulation.
F6 Select V.32 bis or V.32 4800 line modulation.
F7 Select V.32 bis 7200 line modulation.
F8 Select V.32 bis or V.32 9600 line modulation.
F9 Select V.32 bis 12000 line modulation.
F10 Select V.32 bis 14400 line modulation.
H0 Initiate a hang-up sequence.
H1 If on-hook, go off-hook and enter command mode.

I0 Report product code.
I1 Report pre-computed checksum.
I2 Report OK.
I3 Report firmware revision, model, and interface type.
I4 Report response "Telenetics Inc. Rev"
I5 Report the country code parameter.
I6 Report modem data pump model and code revision.
I7 Reports the DAA code
L0 Set low speaker volume.
L1 Set low speaker volume.
L2 Set medium speaker volume.
L3 Set high speaker volume.
M0 Turn speaker off.
M1 Turn speaker on during handshaking and turn speaker off while receiving carrier.
M2 Turn speaker on during handshaking and while receiving carrier.
M3 Turn speaker off during dialing and receiving carrier and turn speaker on during answering.
N0 Turn off automode detection.
N1 Turn on automode detection.
O0 Go on-line.
O1 Go on-line and initiate a retrain sequence.
PForce pulse dialing.
Q0 Allow result codes to DTE.
Q1 Inhibit result codes to DTE.
Sn Select S-Register as default.
Sn? Return the value of S-Register n.
=v Set default S-Register to value v.
?Return the value of default S-Register.
TForce DTMF dialing.

V0 Report short form (terse) result codes.
V1 Report long form (verbose) result codes.
W0 Report DTE speed in EC mode.
W1 Report line speed, EC protocol and DTE speed.
W2 Report DCE speed in EC mode.
X0 Report basic call progress result codes, i.e., OK, CONNECT, RING, NO CARRIER (also,
for busy, if enabled, and dial tone not detected),NO ANSWER and ERROR.
X1 Report basic call progress result codes and connections speeds (OK, CONNECT, RING,
NO CARRIER (also, for busy, if enabled, and dial tone not detected), NO ANSWER, CONNECT
XXXX, and ERROR.
X2 Report basic call progress result codes and connections speeds, i.e., OK, CONNECT,
RING, NO CARRIER (also, for busy, if enabled, and dial tone not detected), NO ANSWER,
CONNECT XXXX, and ERROR.
X3 Report basic call progress result codes and connection rate, i.e., OK, CONNECT, RING,
NO CARRIER, NO ANSWER, CONNECT XXXX, BUSY, and ERROR.
X4 Report all call progress result codes and connection rate, i.e., OK, CONNECT, RING, NO
CARRIER, NO ANSWER, CONNECT XXXX, BUSY, NO DIAL TONE and ERROR.
Y0 Disable long space disconnect before on-hook.
Y1 Enable long space disconnect before on-hook.
Z0 Restore stored profile 0 after warm reset.
Z1 Restore stored profile 1 after warm reset.
&C0 Force RLSD active regardless of the carrier state.
&C1 Allow RLSD to follow the carrier state.

&D0 Interpret DTR ON-to-OFF transition per &Qn:
&Q0, &Q5, &Q6 The modem ignores DTR.
&Q1, &Q4 The modem hangs up.
&Q2, &Q3 The modem hangs up.
&D1 Interpret DTR ON-to-OFF transition per &Qn:
&Q0, &Q1, &Q4,.
&Q5, &Q6 Asynchronous escape.
&Q2, &Q3 The modem hangs up.
&D2 Interpret DTR ON-to-OFF transition per &Qn:
&Q0 through &Q6 The modem hangs up.
&D3 Interpret DTR ON-to-OFF transition per &Qn:.
&Q0, &Q1, &Q4,.
&Q5, &Q6 The modem performs soft reset.
&Q2, &Q The modem hangs up.
&F0 Restore factory configuration 0.
&F1 Restore factory configuration 1.
&G0 Disable guard tone.
&G1 Disable guard tone.
&G2 Enable 1800 Hz guard tone.
&J0 Set S-Register response only for compatibility.
&J1 Set S-Register response only for compatibility.
&K0 Disable DTE/DCE flow control.
&K3 Enable RTS/CTS DTE/DCE (Hardware) flow control.
&K4 Enable XON/XOFF DTE/DCE (Software) flow control.
&K5 Enable transparent XON/XOFF flow control.
&K6 Enable both RTS/CTS and XON/XOFF flow control.
&L0 Select dial up line operation.
&L1 Select leased line operation.

&M0 Select direct asynchronous mode.
&M1 Select sync connect with async off-line command mode. *
&M2 Select sync connect with async off-line command mode and enable DTR dialing of directory
zero. *
&M3 Select sync connect with async off-line command mode and enable DTR to act as
Talk/Data switch. *
&P0 Set 10 pps pulse dial with 39%/61% make/break.
&P1 Set 10 pps pulse dial with 33%/67% make/break.
&P2 Set 20 pps pulse dial with 39%/61% make/break.
&P3 Set 20 pps pulse dial with 33%/67% make/break.
&Q0 Select direct asynchronous mode.
&Q1 Select sync connect with Async off-line command mode. *
&Q2 Select sync connect with Async off-line command mode and enable DTR dialing of
directory zero. *
&Q3 Select sync connect with Async off-line command mode and enable DTR to act as
Talk/Data switch. *
&Q4 Select Hayes AutoSync mode.
&Q5 Modem negotiates an error-corrected link.
&Q6 Select asynchronous operation in normal mode.
&R0 CTS tracks RTS (Async) or acts per V.25 (sync).
&R1 CTS is always active.
&S0 DSR is always active.
&S1 DSR acts per V.25.
&T0 Terminate any test in progress.

&T1 Initiate local analog loopback.
&T2 Returns ERROR result code.
&T3 Initiate local digital loopback.
&T4 Allow remote digital loopback.
&T5 Disallow remote digital loopback request.
&T6 Request an RDL without self-test.
&T7 Request an RDL with self-test.
&T8 Initiate local analog loop with self-test.
&V Display current configurations.
&W0 Store the active profile in NVRAM profile 0.
&W1 Store the active profile in NVRAM profile 1.
&X0 Select internal timing for the transmit clock.
&X1 Select external timing for the transmit clock.
&X2 Select slave receive timing for the transmit clock.
&Y0 Recall stored profile 0 upon power up.
&Y1 Recall stored profile 1 upon power up.
&Zn=x Store dial string x (to 35) to location n (0 to 3 depending upon modem model).
%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.
%L Return received line signal level.
%Q Report the line signal quality.
\D1 Enable Auto Dial via DTR off to on sequence *PE14400 only
\D0 Disable Auto Dial (default) *PE14400 only
\G0 Disable modem to modem flow control.
\G1 Enable modem to modem flow control.
\H0 Command Mode default
\H1 Lease Line Mode