Sierra Wireless DART 300 User Manual
Sierra Wireless
DART 300 CDPD Modem
User’s Guide
2110212 Rev 1.0
November 2000
DART 300 Modem User’s Guide
Important Notice
Because of the nature of wireless communications, transmission and reception of data can never be guaranteed.
Data may be delayed, corrupted (i.e., have er rors) or b e totally lost. Although significant delays or losses of data are
rare when wireless devices such as the Sierra Wireless modem are used in a normal manner with a well-constructed
network, the Sierra Wireless modem should not be used in situations where failure to transmit or receive data could
result in damage of any kind to the user or any other party, including but not limited to personal injury, death, or loss
of property. Sierra Wireless, Inc., accepts no responsibility for damages of any kind resulting from delays or errors
in data transmitted or received using the Sierra Wireless modem, or for failure of the Sierra Wireless modem to
transmit or receive such data.
Safety and Hazards
WARNING
While this device is in operation, a separation distance of at least 20cm must be
maintained between the radiating antenna and the body of all persons exposed to the
transmitter to meet FCC exposure guidelines.
Do not operate the Sierra Wireless modem in areas where blasting is in progress, where explosive atmospheres may
be present, near medical equipment, near life support equipment, or any equipment which may be susceptible to any
form of radio interference. In such areas, the Sierra Wireless modem MUST BE TURNED OFF. The Sierra
Wireless modem can transmit signals that could interfere with this equipment.
Do not operate the Sierra Wireless modem in any aircraft, whether the aircraft is on the ground or in flight. In
aircraft, the Sierra Wireless modem MUST BE TURNED OFF. When operating, the Sierra Wireless modem can
transmit signals that could interfere with various onboard systems.
The driver or operator of any vehicle should not operate the Sierra Wireless modem while in control of a vehicle.
Doing so will detract from the driver or operator’s control and operation of that vehicle. In some states and
provinces, operating such communications devices while in control of a vehicle is an offense.
Patents
Portions of this product are covered by some or all of the following US patents: D367062, D372248, D372701,
5515013, 5617106, 5629960, 5682602, 5748449, and other patents pending.
Copyright
©2000 Sierra Wireless, Inc. All rights reserved.
Printed in Canada.
No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any
means, without the prior permission of the publisher.
The information in this manual is subject to change without notice and does not represent a commitment on the part
of Sierra Wireless, Inc. Sierra Wireless, Inc. shall not be liable for incidental or consequential damages resulting
from the furnishing, p erformance, o r use of this manual.
Trademarks
Windows® and Microsoft® are registered trademarks of Microsoft Corporation.
™
Hayes
is a trademark of Hayes Microcomputer Products, Inc.
All other brand or product names, logos, trademarks, etc. mentioned in this manual are owned by their respective
companies.
2110212 Rev 1.0 Page i
DART 300 Modem User’s Guide
Regulatory Information
The equipment certifications appropriate to your device are marked on the device and the accompanying product
specific information. Where appropriate, the use of the equipment is subject to the following conditions:
CAUTION
Unauthorized modifications or changes not expressly approved by Sierra Wireless, Inc.
could void compliance with regulatory rules, and thereby your authority to use this
equipment.
WARNING (EMI) - United States FCC Information
This equipment has been tested and found to comply with the limits for a Class B
digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to
provide reasonable protection against harmful interference in an appropriate
installation. This equipment generates, uses, and can radiate radio frequency energy
and, if not installed and used in accordance with the instructions, may cause harmful
interference to radio communication. However, there is no guarantee that interference
will not occur in a particular installa tion. If this equipment does cause harmful
interference to radio or television reception, which can be determined by turning the
equipment off and on, the user is encouraged to try to correct the interference by one or
more of the following measures:
•
Reorient or relocate the receiving antenna
•
Increase the separation between the equipment and receiver
•
Connect the equipment into an outlet on a circuit different from that to which the
receiver is connected
•
Consult the dealer or an experienced radio/TV technician for help
WARNING – FCC RF Exposure Guidelines
While this device is in operation, a separation distance of at least 20cm must be
maintained between the radiating antenna and the body of all persons exposed by the
transmitter to meet FCC exposure guidelines.
This transmitter is only approved to operate with an antenna not exceeding 1.5 watts
total system ERP (effective radiated power) for operations with the antenna located at
more than 20 cm from all persons. The warning label must be displayed at the base of
the antenna, clearly visible to all persons exposed to the transmitter.
WARNING (EMI) – Canada
This digital apparatus does not exceed the Class B limits for radio noise emissions
from digital apparatus as set out in the interference causing equipment standard
entitled 'Digital Apparatus', ICES-003 of the Department of Communications.
Cet appareil numérique respecte les limites de bruits radioélectriques applicables aux
appareils numériques de Classe B prescrites dans la norme sur le matériel brouilleur:
'Appareils Numériques', NMB-003 édictée par le ministre des Communications.
Page ii 2110212 Rev 1.0
DART 300 Modem User’s Guide
RSA Licensee
If you have purchased this product under a United States Government contract, it shall be subject to
restrictions as set forth in subparagraph (c)(1)(ii) of Defense Federal Acquisitions Regulations
(DFARs) Section 252.227-7013 for Department of Defense contracts, and as set forth in Federal
Acquisitions Regulations (FARs) Section 52.227-19 for civilian agency contracts or any successor
regulations. If further government regulations apply, it is your responsibility to ensure compliance
with such regulations.
Contact Information
Technical
Support:
Sales Desk:
Post: Sierra Wireless, Inc.
Fax: 1-604-231-1109
Web: www.sierrawireless.com
Your comments and suggestions on improving this documentation
are welcome and appreciated. Please email your feedback to
documentation@sierrawireless.com
Canada/US: 1-877-231-1144
Worldwide: 1-604-231-1128
Hours: 6:00am to 5:00pm Pacific Time
e-mail: support@sierrawireless.com
Phone: 1-604-232-1488
Hours: 8:00am to 5:00pm Pacific Time
e-mail: sales@sierrawireless.com
13575 Commerce Parkway
Suite 150
Richmond, BC
Canada V6V 2L1
. Thank you.
Consult our website for
up-to-date product descriptions, documentation,
applicati on notes, firmware upgrades,
troubleshooting tips, and press releases:
www.sierrawireless.com
2110212 Rev 1.0 Page iii
DART 300 Modem User’s Guide
Page iv 2110212 Rev 1.0
DART 300 Modem User’s Guide
Contents
Introduction
1. About this Guide ...........................................................................1
1.1. Introduction............................................................................................................1
1.1.1.
1.1.2.
1.1.3.
1.2. References...............................................................................................................4
1.3. Currency.................................................................................................................4
1.4. Conventions Used in this Reference .....................................................................4
How to Proceed......................................................................................1
Document Structure................................................................................2
DART 300 Checklist..............................................................................3
2. System Overview...........................................................................7
2.1. Typical System View..............................................................................................7
2.1.1.
2.1.2.
2.1.3.
2.1.4.
2.2. Project Stages.........................................................................................................9
In the Field .............................................................................................8
The Network Connection .......................................................................8
The Central Monitor...............................................................................9
Client / Server.........................................................................................9
2.2.1.
2.2.2.
2.2.3.
2.2.4.
Stage 1 – Application Planning..............................................................9
Stage 2 – Bench Integration and Testing..............................................10
Stage 3 – Field Installation and Testing...............................................10
Stage 4 – Rollout..................................................................................10
3. Getting Started ............................................................................11
3.1. Introduction..........................................................................................................11
3.2. Service Activation ................................................................................................11
3.3. Set-up Considerations..........................................................................................12
3.3.1.
3.3.2.
3.3.3.
3.3.4.
3.4. Connections ..........................................................................................................13
3.5. CDPD Configuration ...........................................................................................13
Power Supply.......................................................................................12
Antenna................................................................................................12
Serial Cable..........................................................................................12
Host Computer Terminal......................................................................12
2110212 Rev 1.0 Page v
DART 300 Modem User’s Guide
3.6. CDPD Network Registration.............................................................................. 14
3.6.1.
3.6.2.
Verifying Network Registration.......................................................... 14
PING.................................................................................................... 15
Feature Reference
4. Local DTE/DCE Interface............................................................ 17
4.1. Modem Modes and States................................................................................... 17
4.1.1.
4.1.2.
4.1.3.
4.1.4.
4.1.5.
4.2. Modem Buffers.................................................................................................... 20
4.2.1.
4.2.2.
4.3. AT Command Handling and Defaults............................................................... 21
Modes.................................................................................................. 17
States ................................................................................................... 18
Conditions............................................................................................ 18
Sessions ............................................................................................... 18
Transition Between States ................................................................... 18
Command Buffer................................................................................. 20
Data Buffers......................................................................................... 20
4.3.1.
4.3.2.
4.3.3.
4.3.4.
4.4. RS-232C Interface and Control Signals............................................................ 25
4.4.1.
4.4.2.
4.4.3.
General Notes...................................................................................... 21
Parameters ........................................................................................... 21
Responses and Results Returned by the Modem................................. 21
Registers.............................................................................................. 24
Interface Settings................................................................................. 25
Flow Control........................................................................................ 25
Control Signals.................................................................................... 26
5. Product Features........................................................................ 29
5.1. Friends Only ........................................................................................................ 29
5.2. Dial Directory ...................................................................................................... 30
5.3. Auto-dial on Start-up.......................................................................................... 31
5.4. Sleep Mode........................................................................................................... 32
5.5. Using Ring Indicator (RI) with Host Sleep .......................................................34
5.6. CDPD Radio and Booster Support .................................................................... 36
5.7. Upgradability....................................................................................................... 36
Page vi 2110212 Rev 1.0
DART 300 Modem User’s Guide
6. Protocols and Packet Assembly Features.................................37
6.1. Communication Protocols and Stacks................................................................37
6.1.1.
6.1.2.
6.2. User Datagram Protocol (UDP)..........................................................................38
6.2.1.
6.2.2.
6.2.3.
6.2.4.
6.3. Transmission Control Protocol (TCP)...............................................................43
6.3.1.
6.3.2.
6.3.3.
6.3.4.
6.3.5.
6.4. Serial Line Interface Protocol (SLIP).................................................................45
6.5. Point-to-Point Protocol (PPP)............................................................................. 45
6.6. Packet Assembly Management ...........................................................................46
DART 300 Internal Protocol Stacks.....................................................38
Packet Service Modes ..........................................................................38
UDP Server Features............................................................................39
UDP Client Features.............................................................................41
Closing UDP Sessions..........................................................................41
UDP Broadcast and Multicast..............................................................42
TCP Handshaking ................................................................................43
TCP Server Features.............................................................................43
TCP Client Features .............................................................................44
Closing a TCP Session.........................................................................44
TCP and Sleep Mode............................................................................45
6.6.1.
6.6.2.
6.6.3.
6.6.4.
Assembling a Packet ............................................................................46
Forwarding a Packet.............................................................................46
Escaping Data State..............................................................................47
Data and Telemetry Considerations .....................................................50
7. Advanced Features.....................................................................53
7.1. Multiple CDPD Accounts....................................................................................53
7.2. Controlling Network Registration......................................................................54
7.2.1.
7.2.2.
7.3. Monitoring the Network Connection..................................................................60
7.3.1.
7.3.2.
7.3.3.
Channel Acquisition .............................................................................54
Registration..........................................................................................57
LED Indicator.......................................................................................60
Radio Signal Monitors..........................................................................60
Registration Status................................................................................61
2110212 Rev 1.0 Page vii
DART 300 Modem User’s Guide
Configuration and Use
8. UDP/TCP Service ........................................................................ 63
8.1. Introduction......................................................................................................... 63
8.2. Configuration Checklist for UDP/TCP Service................................................ 63
8.2.1.
8.2.2.
8.2.3.
8.2.4.
8.2.5.
8.2.6.
8.3. Using UDP/TCP Service ..................................................................................... 66
8.3.1.
8.3.2.
8.4. Sample UDP/TCP Configurations ..................................................................... 73
8.4.1.
8.4.2.
NEI and Channel Restrictions ............................................................. 63
Registration and Sleep Mode............................................................... 64
Service Options ................................................................................... 64
Packet Assembly and Forwarding Options.......................................... 65
Escape Options.................................................................................... 65
Save Configuration.............................................................................. 66
Server Sessions.................................................................................... 66
Client Sessions..................................................................................... 70
Case 1 – Semi-intelligent RTU............................................................ 73
Case 2 – Dumb Meter.......................................................................... 75
9. SLIP/PPP Service........................................................................ 79
9.1. Serial Line Interface Protocol (SLIP)................................................................ 79
9.1.1.
9.1.2.
9.1.3.
9.2. Point to Point Protocol (PPP)............................................................................. 82
9.2.1.
9.2.2.
9.2.3.
Configuring SLIP Service....................................................................79
Using SLIP Service .............................................................................81
Closing a SLIP Session........................................................................ 82
Configuring PPP Service..................................................................... 82
Using PPP Service............................................................................... 84
Closing a PPP Session......................................................................... 84
Intstallation
10. Device Attachment...................................................................... 87
10.1. Antenna Connection..................................................................................... 87
10.2. 3-Watt Class I Booster Operation............................................................... 88
10.2.1. Connection........................................................................................... 88
10.3. The Serial Connector................................................................................... 89
10.3.1. Null-Modem Connection ..................................................................... 89
10.3.2. Cable Length ....................................................................................... 90
Page viii 2110212 Rev 1.0
DART 300 Modem User’s Guide
10.4. Power Connection.........................................................................................91
11. Installation Considerations.........................................................93
11.1. Environment..................................................................................................93
11.1.1. Temperature and Auto Shutdown.........................................................93
11.1.2. Temperature vs. Duty Cycle.................................................................93
11.2. Access.............................................................................................................94
11.3. Power Supply.................................................................................................94
11.3.1. Grounding ............................................................................................94
11.3.2. Wire Splicing........................................................................................94
11.3.3. Crimp Terminals ..................................................................................95
11.4. Mounting .......................................................................................................95
References
12. AT Commands and Status Registers.........................................97
12.1. Introduction...................................................................................................97
12.2. AT Command Set..........................................................................................97
12.3. CDPD Status Registers...............................................................................107
12.3.1. S-Registers in CDPD Mode ...............................................................107
12.3.2. WS-Registers in CDPD Mode............................................................109
12.4. Important Notes and Dependencies...........................................................116
12.5. Result Codes................................................................................................116
12.6. Stored Profile Settings for CDPD Mode...................................................117
13. Troubleshooting........................................................................119
13.1. Introduction.................................................................................................119
13.2. General Communication Problems...........................................................119
13.3. General Modem Problems .........................................................................120
13.4. CDPD Network / Connectivity Problems..................................................121
13.5. Warranty.....................................................................................................121
13.5.1. Warranty Registration........................................................................121
13.6. Obtaining Service........................................................................................122
2110212 Rev 1.0 Page ix
DART 300 Modem User’s Guide
14. Specifications ........................................................................... 123
14.1. Power Specifications .................................................................................. 123
14.1.1. Power Connector............................................................................... 123
14.2. Radio Specifications................................................................................... 123
14.2.1. Antenna Specifications...................................................................... 124
14.2.2. Regulatory Approvals........................................................................ 124
14.3. Environmental Specifications.................................................................... 125
14.4. Application Interface Specifications......................................................... 125
Page x 2110212 Rev 1.0
1. About this Guide
1.1. Introduction
This User’s Guide is designed to assist application software developers with the set-up,
installation, testing, and design of applications for the DART 300.
You should be familiar with the use of modems, communication media (PSTN and Cellular),
protocols such as TCP/IP and UDP, and the use of AT commands.
DART 200
Introduction
For users already familiar with the Sierra Wireless DART 200, there is a detailed
migration guide (document 2110291) identifying differences between the models. It is
intended to guide the user to the functional areas needing changes for the DART 300
implementation.
Boxes like this one appear as needed throughout this guide to highlight particularly
important migration notes.
1.1.1. How to Proceed
Integrating the DART 300 into a system requires a good understanding of the modem, the local
host device that the DART will connect to, and the communication network that connects the field
units to the monitoring host(s). All users are strongly encouraged to read this guide to ensure
that the configuration choices are the best ones to meet your needs.
For those users with a clear grasp of the issues, a Focus List is provided to direct you to the key
sections of this guide that will quickly get a modem configured for UDP or TCP operation and test
it in your system. There a re boxes in the margin t o highlight these key sections throughout this
guide.
Focus List
• 2.2 Project Stages – an overview of the integration project
• 3.2 Service Activation – acquiring a CDPD service account
• 3.3 Set-up Considerations – setting up the DART on the test bench
• 3.4 Connections – connecting to a PC for modem configuration
• 3.5 CDPD Configuration – sett ing the modem NEI
• 6.6 Packet Assembly Management – using the PAD and escaping data state
• 8.2 Configuration Checklist for UDP/TCP Service – steps to configure the modem
• 8.4 Sample UDP/TCP Configurations – additional configuration guidance
• 10 Device Attachment – connecting to the host device for system testing
• 11 Installation Considerations – field installation issues
2110212 Rev 1.0 Page 1
Introduction DART 300 Modem
1.1.2. Document Structure
This guide is organized into the following primary “books” and sections. For those needing some
background on the CDPD network, a primer is available from our website.
Book 1 – Introduction
The guide begins with an overview of the product and where it fits in a telemetry system. Also
covered are instructions to get your DART 300 connected to a computer and the CDPD network to
confirm that it is operational.
• Section 1, About this Guide, introduces the reader to how to use this document and
understand the c onventions.
• Section 2, System Overview, is a high level look at the layout of the system and
offers suggestions for the project develo pment. This secti on helps you determine the
type of configuration best suited to the needs of various host devices.
• Section 3, Getting Started, provides the basic information needed to install, set-up,
and test the modem on the CDPD network using a personal computer.
Book 2 – Feature Reference
The DART 300 is a feature-rich product for use in a wide variety of systems. This section
describes the many features of the product so that you can plan how to make full use of the
modem to meet your needs.
• Section 4, Local DTE/DCE Interface, describes in detail the nature of the interface
between the DART 300 and the local host device. This is essential to establishing a
robust connection between the two components. Terminology of modes and states is
introduced, and both the AT command and the RS-232 interfaces are explained.
• Section 5, Product Features, introduces the primary features of the DART 300. It
covers Friends Only, the Quick Dial Directory, Auto-dial on Start-up, and Sleep
modes.
• Section 6, Protocols and Packet Assembly Features, discusses the protocol options
available (TCP, UDP, SLIP/PPP), and their respective advantages and disadvantages.
Also included are the features of the internal Packet Assembly / Disassembly (PAD)
service for the TCP and UDP stacks.
• Section 7, Advanced Features, covers less commonly used capabilities of the
modem. These include multiple CDPD accounts, controlling the network
registration process, and moni toring the network connection.
Book 3 – Configuration and Use
This is the core of how to configure and operate the modem in various settings with specific
example applications.
• Section 8, UDP/TCP Service, guides the modem configuration for applications
needing the modem to provide IP and packet assembly/disassembly services. The
UDP and TCP packet services in the DART 300 for both server and client sessions
are discussed. Detailed examples are included.
• Section 9, SLIP/PPP Service, describes using the SLIP/PPP interface to the modem.
This is for users with an intelligent host system, managing its own IP stack.
Page 2 2110212 Rev 1.0
User’s Guide About This Guide
Book 4 – Installation
The physical issues of installing and connecting the modem are covered in this portion of the
guide. This covers both field installations and bench connections for configuration and testing.
• Section 10, Device Attachment, describes antenna and booster connections, the RS-
232 cabling to the DART (including what a null modem is, and how to determine if
one is required), and the power connection.
• Section 11, Installation Considerations, discusses the items to consider when
installing the DART 300 in the field. This includes environmental, access, mounting
and grounding issue s .
Book 5 – References
This section includes references for the AT commands and status registers, troubleshooting tips,
and the product specifications.
• Section 12, AT Commands, provides details on AT commands, status registers, result
codes, and stored profiles.
• Section 13, Troubleshooting, provides problem symptoms and suggested remedies.
The warranty and service details are also provided in this section.
• Section 14, Specifications, summarizes the physical, electrical, and environmental
specifications for the DART 300 modem.
1.1.3. DART 300 Checklist
Each DART 300 package should include the following parts:
SWI Part No. Description
1100062 DART 300 CDPD Modem
6000067 DC Power Connector to bare wire
In addition, each shipment should include the following:
6000131 DART 300 CDPD Modem User’s Guide (this document)(doc #2110212), and
DART 300 Migration Guide (for users of the DART 200) (doc #2110291)
These optional accessories are also available by contacting the Sierra Wireless sales desk:
6000048 10’ Serial Cable (DTE-DCE) with 9-pin D connectors
6000055 DART 300 Mounting Kit
6000082 AC Power adapter with DART 12V DC connector
6000065 Fixed Mount Antenna
1100051 AirBooster 350 RF Amplifier
2000096 DART 300 to AirBooster 350 Connecting Cable
For those who wish to use the Sierra Wireless Watcher enabling software to configure and use the
modem, the software can be downloaded from the Sierra Wireless website at
www.sierrawireless.com
2110212 Rev 1.0 Page 3
.
Introduction DART 300 Modem
1.2. References
For background information on the nature of wireless communications consult your cellular
service provider and/or their Internet site. All major service providers provide web-based
information on CDPD.
The Sierra Wireless web site at www.sierrawireless.com
Support and Downloads section. This library includes other useful documents such as:
1.3. Currency
This document may be revised from time to time as new firmware and features are made available.
Please check our web site frequently for revisions. This edition is:
This document is current with the following modem firmware revisions:
DART 300 / SB300
Revision R1.3.5. To determine your firmware revision:
1. Enter the Identification command ATI5
The modem will respond with the Firmware revision information:
R1_3_5 …
The details following the revision number include Sierra Wireless information on the specific
build followed by the date and time of the build.
If your modem firmware is an earlier version, consult the Sierra Wireless website or contact Sierra
Wireless Technical Support to acquire an upgrade.
includes a document library in the
• CDPD Primer, 2130006
• Glossary of Terms and Acronyms, 2110032
• Problem Report Sheet, 2110125
Rev 1.0 November 17, 2000
1.4. Conventions Used in this Reference
Local host means the telemetry device (DTE) connected to the DART 300 modem (DCE).
Remote host means the central monitoring system being used to collect the telemetry data from the
local device. Discussion is from the point of view of the DART 300 modem.
Result Code – This is a numeric or text code that is returned after all AT commands (except
resets).
Response – This term indicates a response from the modem, which is issued prior to a result code.
Reading registers or issuing commands that report information will provide a response followed
by a result code unless the command generates an error.
Numbers are assumed decimal. Hexadecimal values are shown with a prefix of 0x, i.e. in the form
0x6B. Binary values are shown with a prefix of 0b, i.e. in the form 0b01101011.
Character codes that are described with words or standard abbreviations are shown within angle
brackets: such as <CR> for Carriage Return and <SP> for a blank space character.
AT Command and register syntax is noted using an alternate font:
AT+WS46=4
Responses and result codes from the modem are shown in an alternate font:
NO CARRIER
Page 4 2110212 Rev 1.0
User’s Guide About This Guide
WARNING
Notes in this form denote a physical hazard. The warning calls attention to a
procedure or practice, which, if not performed correctly, could result in personal
injury.
CAUTION
Notes in this form highlight a procedure or practice which, if not performed correctly,
could result in loss of data or damage to equipment. This is also used to highlight
issues related to regulatory limitations.
NOTE
This form of note draws attention to procedures or practices which, if not performed
correctly, could result in failure of a process or improper configuration. These are
typically pre-requisites to other operations.
DART 200
Operational differences between the DART 300 and the older DART 200 are noted in
boxes with this figure. These notes only apply to users who are familiar with the
DART 200 and may have integration issues due to feature differences.
2110212 Rev 1.0 Page 5
Introduction DART 300 Modem
Page 6 2110212 Rev 1.0
2. System Overview
Sierra Wireless’ DART 300 modem provides fast, reliable, cost effective communications for your
fixed-location data, telemetry, or SCADA application. Remote terminals are often in “out of the
way”, “hard to get to” locations. The DART 300 provides the reliability and high performance
that you demand and rely on for these mission critical systems.
The DART 300 is a full duplex, 0.6 Watt, wireless radio modem that provides communications
over the Cellular Digital Packet Data (CDPD) network.
Its low power needs, and specific telemetry features make it the ideal solution for applications
such as water distribution and management, oil and gas distribution, electricity distribution,
electronic traffic signs, and many others. With its internal UDP and TCP stacks, it can be used
with a wide variety of remote devices and equipment.
Before beginning the integration of the DART 300 into a system, it is useful to have a look at the
system as a whole and the common project development steps to full implementation.
2.1. Typical System View
Most installations of the DART 300 are in fixed (non-mobile) locations where a device in the field
is collecting data, a meter or Remote Telemetry Unit (RTU) for example, or controlling
something, a valve or display board perhaps. Since CDPD is wireless, it can also be used in
mobile applic ations (although p ower supply may be an issue).
The unit is typically polled for data by a host system, which usually monitors or controls several
field units. In some cases the field device initiates messages based on detected events.
Figure 2-1: DART 300 CDPD Modem
2110212 Rev 1.0 Page 7
Introduction DART 300 Modem
DART 300
DART 300
RTU
RTU
2.1.1. In the Field
The DART 300 is connected to a local device in the field (shown in the figure above as a RTU),
and a power supply (sometimes from photovoltaic cells or batteries). The local host will be
referred to in this document as the Data Terminal Equipment (DTE) even in cases where the serial
connection it uses is configured as communication equipment (DCE). See Section 10.3 for a
discussion of this distinction.
The local device could be something simple like a meter that outputs a data block, at fixed
intervals, containing its readings. This type of device is not capable of receiving or responding to
data; as such it is considered a “dumb” device.
At the other extreme, the local device could be an intelligent device such as a computer running a
multi-tasking operating system like Windows or Linux. T he PC may be responsible for
coordinating the input of several sensors and in turn controlling outputs to various devices. The
local host in this case can manage a complex communication protocol to send telemetry data and
receive operational commands.
Internet
Radio Tower
Base Station
Figure 2-2: Typical DART 300 Telemetry System
Monitoring System
The host device connected to the DART 300 modem does not have to support the Attention (AT)
command set directly to operate with the modem. The modem can be configured to power up to a
state where connection is controlled by the remote host or initiated automatically by the modem.
Devices capable of issuing a configuration string have the added ability to initiate their own
connections; however, these systems should also provide fault recovery capability.
In any case, the DART 300 can provide the data link between the local device and a network
connection to the central monitoring/control station.
2.1.2. The Network Connection
A CDPD Service Provider handles the infrastructure of cellular antenna towers and base stations.
The base station converts radio signals to a standard network co nnection. This may use wires,
fibre optics, or microwave transmissions.
The network connection is usually the Internet (as shown in the figure above) but can be a private
frame relay network if security is an issue.
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2.1.3. The Central Monitor
The units in the field are typically linked to a central computer used to monitor, and possibly
control them. In most cases the connection uses a standard Internet service. The monitoring
system can be connected to the network by any means, including another DART 300 using the
CDPD network.
Since this document takes the point of view of the DART 300 in the field location, the central
monitoring system is considered remote while the DART modem is local.
This remote host must be able to receive the data from multiple local field units and distinguish
one from another. This may be done by polling the individual stations in turn, or by maintaining
different IP ports (sockets) for each device.
2.1.4. Client / Server
In any data exchange over IP, there must be a client (originating the session) and a server
(responding to client requests).
If the central monitoring system uses a polling method to collect data, the monitor acts as a client,
soliciting data from the units in the field (servers). Most telemetry installations use polling to
collect data. In this case, the modem is configured as a server to auto-answer the calls from the
central host.
In cases where the field units initiate the call to report an event or periodic block of data, they are
the clients, calling the central server. The central server may maintain many sessions
simultaneously, accepting data and issuing responses. This is more rare, but is still supported by
the DART 300 modem.
2.2. Project Stages
To integrate the DART 300 into a system requires several stages or steps. This outline covers a
typical case but may not apply to all situations.
2.2.1. Stage 1 – Application Planning
The first task is to define the system requirements, and how the various components of the
network should be configured to meet those requirements. Many of these choices have impacts on
other choices such that the whole system needs to be considered and balanced to maintain
integrity.
After reading about the DART 300 in this guide, you should be equipped to make these decisions.
The nature of the local host device may dictate the answers to many of these issues.
Issues to consider are:
• Local host capability. Dumb devices can only transmit. Semi-intelligent devices can receive
commands using a proprietary protocol but cannot issue or manage AT commands to the
modem. Intelligent devices can be programmed to manage the modem using AT commands.
• IP Stack Location. If the host device is dumb, the modem will have to provide the IP stack
and packet service (UDP or TCP). Semi-intelligent devices may or may not include an IP
stack as part of their communication protocol. If the local host is intelligent and implements a
stack, then a SLIP or PPP connection to the DART may be preferred.
• Client/Server. Determine which end will originate connections. The answering station will
require a fixed IP address so that callers know where to route packets. The DART 300 has a
fixed IP address (its Network Entity Identifier or NEI). The central monitoring station may or
may not. If not, then the monitor will have to originate calls to the modem. That makes the
DART 300 modem a server.
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Introduction DART 300 Modem
• Protocol. Selection of UDP or TCP is important to determining the best configuration for
controlling the opening and closing of sessions, maintaining data integrity over large file
transfers, and keeping network overhead low.
• Security. Implementation of the Friends Only feature will depend on the client/server
relationship and whether or not the central host will always use the same IP address. If there
is concern about improper access to the field device, and the DART 300 / local host can act as
a client, then the registration process could be handled manually. This means the local unit is
only connected to the network when it is ready to contact the remote host.
• Power Consumption. If there are concerns about the amount of power available in the field
locations, use of the modem’s sleep modes may be needed. If the local host is capable of
sleeping, the implementation of the Ring Indicator (RI) signal from the modem can be used to
control host wake-ups.
To fully understand the options made available by the DART 300, the system designer should read
the Feature Reference sections (4 through 7) of this manual.
During this first stage, planning may also be needed to resolve the physical installation issues of
power supply, ante nna installation and grounding, and cabling. A review of the Installation
sections (10 and 11) will prepare you for these issues.
2.2.2. Stage 2 – Bench Integration and Testing
Before installation in the field, the DART 300 requires configuration and testing. One or two
units should be set-up on the test bench and connected to the CDPD network and a PC or terminal
device. Following configuration, the modem must be connected to the target host device and
tested.
There are several steps to this testing:
1. Physical connection to: a power supply, a host PC, and an antenna with access to CDPD
coverage.
2. Initial configuration for activation on the CDPD network. This step will test that the modem
can connect to, and register with, the CDPD network, and respond to a PING.
3. Configuration for use with the local host device. This configuration is performed with a
terminal (PC) to prepare the modem for use with the target device.
4. Connection and test with the local host device. This may involve different serial cabling if the
local host is configured as a DCE device. This step tests that the device will work with the
modem and communicate over the network to the monitoring system. Extensive testing of
fault tolerance should be performed to ensure that problems in the field are self-correcting or
can be corrected remotely.
The first two steps above are covered in Section 3, Getting Started. The configuration and testing
with the target device should happen after reading the balance of this guide.
2.2.3. Stage 3 – Field Installation and Testing
Before configuring and installing many units, it is advisable to install one or two field units to
verify power connection and consumption, antenna installation and net work coverage,
connectivity, and end-to-end performance. Only when this stage passes should you rollout the full
system.
Custom power connectors, data cables, and mounting hardware may be required for the field
installation. This step allows you to verify that the connections are working and the system
functions as required.
2.2.4. Stage 4 – Rollout
This involves configuring many DART 300 units. Each must have the same configuration as the
units that passed the field trial; except the CDPD activation (NEI) will be different for each unit.
Depending on the scale of the system, this can b e done by hand or through an automated script.
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3. Getting Started
3.1. Introduction
This chapter guides you through the initial physical set-up of a host terminal (usually a PC) and
the DART 300 modem, for configuration and test purposes. Related start-up issues such as
cellular activation are also covered.
After completing this chapter, you should be able to communicate (DTE to DCE) with the modem
by using AT commands from a host terminal, have the modem connect with, and register on, the
CDPD network (assuming coverage), and have the modem respond to a PING from the network.
This section presumes the modem is in its factory default configuration. The instructions provided
here are only those needed to make the initial connections and do not reflect the full flexibility of
the modem. The Feature Reference sections cover considerably more detail.
Typical application configurations for connection to the target host device are not covered until the
Configuration and Use sections.
3.2. Service Activation
Before you can use your modem for wireless communication you must obtain an I nt ernet
Protocol (IP) address for it from a cellular service provider. This address is often referred to as a
Network Entity Identifier (NEI). This section describes what they will need to know and what
information they will provide to you.
To obtain an IP address for your modem for use on CDPD networks, contact your local CDPD
service provider and give the service provider the Equipment Identifier (EID). This is the
identification number of the radio/modem. A Sierra Wireless modem EID has the following
format:
00-A0-D5-xx-xx-xx
Look for this number on the back of your modem and on a label affixed to the outside of the
package that the modem was shipped in.
The EID number is also available by querying the modem with the AT+WPEID command.
The CDPD service provider supplies the following:
1. Modem IP address, commonly referred to as a NEI. This identifies your modem on the
CDPD network and on the Internet.
2. IP address of a router or server to ping when testing the connection. This may be a Domain
Name Server (DNS).
Both of the above items are in the form of an IP number. This is made up of four numbers
ranging in value from 0 to 255, separated with periods (sample: 192.168.0.9). This is known
as dotted-decimal format.
3. Side designator, A or B. This determines the channels used by your CDPD service provider.
4. SPNI number of the provider. This is optional. The Service Provider Network Identifier
(SPNI) is used when restricting the modem to accepting service from a limited list of
providers, and can help speed up cellular channel acquisition and registration.
This information will be required when configuring your modem for CDPD registration.
Contact your service provider to get this process started. While the service provider is getting
your account configured, you can install and configure your modem. Record the information
provided by your carrie r for configuring the modem later.
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Introduction DART 300 Modem
3.3. Set-up Considerations
The section covers the requirements for a simple test bench installation of the modem. For full
details of the physical installation of the DART 300 consult Section 10.
3.3.1. Power Supply
The DART 300 package does not include a power supply in the box, as most installations have
12V DC power available at the site. For this initial testing a 12.0V DC regulated power source
with a 1 amp capability is required. The unit comes with a power connector cable with bare wire
leads for connection to a DC power supply.
An AC power adapter, using the DART 300 power connector, is available as an accessory from
Sierra Wireless (part 6000082).
If you chose to provide your own cable, a description of the DART 300 power connector is
provided in Section 10.4. Part numbers are provided for those wishing to assemble custom power
supply cables.
3.3.2. Antenna
There is no antenna supplied with the modem as shipped from Sierra Wireless. The antenna you
choose to use should meet your particular installation requirements. Consult Section 10.1 for
details on the antenna requirements. A 3dB gain magnetic-mount cellular antenna, available from
most electronic stores, is suitable for bench testing activity.
An antenna with a hard mount and TNC connector is available as an accessory from Sierra
Wireless (part 6000065).
3.3.3. Serial Cable
A standard RS-232 serial cable with 9-pin male D connector is required (not provided in the
DART package) for connecting the PC host to the DART 300 modem. A suitable cable is
available from Sierra Wireless (part number 6000048) if needed.
3.3.4. Host Computer Terminal
You will require a PC with a communications program capable of operating in ASCII terminal
emulation mode. This allows the PC to function as a terminal attached to the modem and permits
the entering of AT commands required for modem set-up and diagnostics. We recommend that
the program chosen be capable of logging terminal communications activity to a file for later
analysis or printout in the event that technical support is required.
For IBM PC-compatibles, Windows Terminal, HyperTerminal, ProComm, and Kermit are all
acceptable. If you intend to use SLIP or PPP mode, note that early versions of HyperTerminal do
not allow you to send SLIP framing characters to the modem, preventing use of the escape
sequence. This was corrected in later versions.
Communication between the host (DTE) and the Sierra Wireless DART 300 modem is factory
defaulted to:
bps: 19200
Data Bits: 8
Parity: None
Stop Bits: 1
Any application being used to communicate with the modem and issue AT commands must be
configured this way initially. Auto-baud is not supported in the DART 300.
Flow control is implemented in hardware (RTS / CTS) and is not optional.
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As shipped the modem is configured with these settings:
• Echo enabled (E1): which causes the modem to echo characters received from the host back
to it while in command state. The backspace is echoed as <BS> <SP> <BS>.
• Quiet result codes disabled (Q0): which enables the modem to issue result codes following
commands. Quiet on (Q1) suppresses result codes entirely (but not re sponses).
• Verbose result codes (V1): which provides results in English text appended with <CR><LF>.
Verbose off (V0) returns the results as ASCII numeral codes. Numeric codes are preferred
for software processing by intelligent terminal applications.
This configuration means that a PC host running a terminal emulation progr am for initial
configuration of the modem should use these settings:
• Emulation – TTY
• ASCII character
Sending:
• No line ends with line feeds
• No local character echo
Receiving:
• Do not append line feeds to incoming line ends
• Do not force incoming data to 7-bit.
• Wrap lines if necessary
3.4. Connections
This section describes the steps to connect the PC host and DART 300 modem. At the end of this
procedure you should be ready to configure and use the modem. If results at any step are not as
described, consult the chapter on troubleshooting (Section 13).
To connect follow these steps:
1. Attach the RS-232 serial cable (female end) to a COM port of the host PC.
2. Attach the RS-232 serial cable (male end) from the host to the DART DATA connector.
3. Start the terminal application on the host PC. Configure the application for the port connected
to the DART 300. From the factory, the modem requires a setting of 19200 bps, 8 data, no
parity, 1 stop bit, with hardware (RTS/CTS) flow control.
4. Instruct the terminal application to connect.
5. Place the antenna in a suitable location, and attach the antenna cable to the modem.
6. Ensure the modem power switch is OFF.
7. Connect the 12V DC power supply to the DART 300.
8. Switch on the DART 300 power.
The LED indicator should come on dimly. This indicator is used to display the status of the
modem. The modem initializes and in about 6 to 10 seconds the CTS serial signal should
assert and OK should appear on the PC terminal. The LED will become brighter and may
begin to blink.
9. Type AT<enter> at the host terminal. The modem should reply with OK.
The modem is now ready to be used with the host computer. You may continue to configure and
use the modem as described in sections below.
3.5. CDPD Configuration
In order for the modem to register on a CDPD network it must have a unique Network Entity
Identifier (NEI). This is an Internet Protocol (IP) address assigned by your CDPD network service
provider. Section 3.2 Service Activation contains information on activating this service.
The service provider must assign you an NEI and channel side preference. They should also
provide their Service Provider Network Identifier (SPNI) number. To do this, the service provider
will need to know the Equipment Identifier (EID) of the modem, which you can obtain from the
modem by issuing the +WPEID command .
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Introduction DART 300 Modem
The NEI, and side preference are all that are needed to connect with the network. These are
recorded within the modem by using the following AT commands (the AT is omitted for brevity):
1. +WPNEI=ip where ip is the NEI address to assign in dotted-decimal format. You do not
need leading zeroes in the individual elements of the address. When you press <enter> the
modem will respond with a prompt to confirm the change in the table. The old and new
values are both shown.
Press Y (case insensitive) to confirm the change, or
Press N (or any key other than Y) to cancel the command.
The modem will respond with OK if the NEI is in a valid IP form.
2. +WS174=n where n indicates the application of the channel side (A or B) assigned by your
CDPD provider. Values for n are:
1 – A side preferred,
2 – B side preferred,
3 – A side only,
4 – B side only.
Setting one side preferred will mean the modem searches channels on that side first, but will also
check for CDPD channels on the other side should there be no usable signals on the preferred side.
Restricting the modem to one side only will prevent it from scanning the alternate side channels.
This is usually discouraged in mobile settings but can be done in the fixed (non-mobile)
installations for the DART 300.
When these two elements have been entered, the modem will automatically attempt to register on
the CDPD network.
3.6. CDPD Network Registra ti on
Note that network registration must be performed be fore communication ac ross the network can
begin. Registering on the network is distinct from opening a c ommunication session. The
registration process involves an exchange of identification, authentication, encryption keys, and
CDPD sleep characteristics.
Data Carrier Detect (DCD) is tied to sessions, not network registration. A session does not begin
until you originate a (client) session or answer one (as a server).
The modem can be set to register manually (on command) or automatically when it starts or resets.
For this first test auto-registration is used. This is the factory default setting and no additional
action is required for this setup.
3.6.1. Verifying Network Registration
The status of the modem’s registration can be read at register +WS56 (Network Registration
Status). A value of 1 indicates the modem is registered. A value of 0 indicates that it is not
registered.
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The DART 300 LED indicator also reflects the modem’s registration status. The flash patterns are
as follows:
• On steady (not flashing) indicates power is on but no CDPD channel is visible. The modem is
typically scanning for a channel at this time. During the first few seconds from power-up, the
modem is initializing and the LED will appear dim.
• Flashes on once per second if the modem has acquired a CDPD channel but is not yet
registered.
• Flashes on twice per second if the modem is registered on a CDPD channel.
• Off indicates the modem is in CDPD sleep mode (or has no power).
Monitor the modem’s LED indicator to determine if it can acquire a CDPD channel (flashes once
per second). If it fails to do this within a few minutes then check the antenna connection and
placement. Consult Section 10.1 on antenna installation for guidance.
If the modem can acquire a channel but does not register within a few minutes, you can determine
the reason by attempting a manual registration:
1. +WPDEREG to force the modem out of auto-registration.
2. +WPREG to attempt to register manually.
The modem allows up to 30 seconds to register. If it fails, a reason is given. If the modem has
simply timed out, then retry the registration command in step 2.
A message of DENIED_MDIS_INCAPABLE means that the CDPD network is not able to handle
the registration at this time and you should retry later. If the error persists, contact the CDPD
carrier for assistance.
Any other registration failure, with a DENIED_… message, will require the attention of your
CDPD service provider to clear up the problem. Contact them and report the registration failure
message from the modem. Additional troubleshooting assistance is in Section 13.
When the modem has successfully registered, enter:
3. +WS173=1 to restore auto-registration.
3.6.2. PING
After registration, you should confirm that you can communicate with the modem over the
network.
PING is a utility to test connections across an IP network. PINGs are packets of data with special
flags in the header, which advise the protocol stack at the receiving end to echo the packet back.
The sender typically times the duration from transmission to echo receipt to determine the speed
of the network link. The application at the receiving end of a PING has no knowledge of the
transaction. It is handled within Layer 3 of the protocol stack.
When the modem is registered, you can issue PINGs from another CDPD-based modem, or over
the Internet, and the DART 300 should reply. If you are using a SLIP/PPP connection, the stack
on the host will be responsible for replies to PINGs. If you use either the UDP or TCP packet
services in the DART 300 modem, then the modem will handle the PING without the host’s
knowledge.
DART 200
The DART 200 includes the ability to both answer and generate PINGs (*P) but the
DART 300 only supports answering. PINGs from the DART 300 must originate with
the attached host device using a SLIP/PPP mode connection.
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Introduction DART 300 Modem
3.6.2.1. Obtaining a PING from the M odem
This step assumes the modem is registered on the CDPD network.
(AT is omitted for brevity):
1. +WS45=0 or 1 to select UDP or TCP packet service respectively. This will have the modem
reply to the PING without the need of a local host connection.
2. Using a network-connected PC as the remote station, open a MS-DOS Prompt window.
3. At the MS-DOS command line enter:
PING <ip> where <ip> is the registered NEI address of the modem in dotted-decimal format.
(The modem’s NEI can be determined with the AT command +WPCURNEI.) Do not use
leading zeroes in the IP address components. (The PING utility assumes a leading 0 indicates
an octal rather than decimal value).
The modem should reply and the PC will indicate the echo time. Four PINGs are issued by
this command option.
If the PC PING requests timeout without success, try allowing a longer wait time by adding the
parameter –w 5000 to the PING command line. That will allow 5 seconds (5000 ms) for the echo
before the PC will time out the attempt. For a full list of PING command options, enter the PING
command without parameters.
At this point the modem should be functioning on the network and responding to PINGs. The
modem is now ready for configuration and installation as described in the sections on
Configuration and Use.
Should the modem fail to respond, check Section 13, Troubleshooting.
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Feature Reference
4. Local DTE/DCE Interface
This section covers:
• Important terminology on modem modes and states
• Modem buffers
• The AT Command Interface
• The RS-232C control signals
A sound understanding of the interface is important to smooth communication with devices that
may not handle the modem’s AT commands and responses as well as intelligent local hosts that
can exercise full control of the modem.
4.1. Modem Modes and States
The DART 300 modem supports CDPD only but with several packet service modes. Various
states and conditions within each mode are also possible. The commands and registers used
depend on the modem’s operating mode, state of the modem, and its condition. Together these
determine how the modem will behave in any given situation.
Mode indicates the packet service or local connection used by the modem.
State indicates whether data is treated as a modem command or data for transmission.
Condition indicates whether the modem has an active connection to the network.
4.1.1. Modes
The DART 300 supports all of these modes.
• SLIP – The simplest mode of operation, where the local host system provides TCP or UDP
stack services. This is the factory default.
• PPP – A more robust form of SLIP connection where the local host again provides the
protocol stack. This protocol allows the local host and modem to negotiate the features they
have in common to establish the most effective communication.
• UDP – User Datagram Protocol stack is implemented in the modem where serial data is
assembled into packets, or received data packets are disassembled for the local host.
• TCP – Transport Control Protocol stack is implemented in the modem for packet assembly
and disassembly and the management of connection handshaking with the remote.
UDP and TCP modes are also known as PAD modes because the modem’s internal Packet
Assembler / Disassembler (PAD) services are active.
The mode can be changed whenever the modem does not have an open session.
A full discussion of the protocols is covered in Section 6.
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Feature Reference DART 300 Modem
4.1.2. States
The modem’s state, in conjunction with its condition, will govern how the modem handles traffic
to and from the host and to and from a remote modem.
The modem supports two states:
• Command – the modem exchanges data with its host (DTE) as AT commands and replies.
• Data – communication is passed between the local and remote terminals as telemetry data.
4.1.3. Conditions
In addition to mode and state the modem can be in one of two conditions:
• On-line – actively connected with a network session open (off-hoo k).
• Off-line – disconnected, or without an active network session (on-hook).
While in off-line condition the modem can only be in command state.
In the on-line condition, the modem can be:
• In data state which passes data through the mod em between the local host (DTE) and the
remote terminal or network.
• In command state which exchanges data between the local host (DTE) and the modem (DCE)
without passing it thro ugh t he active connec tion to the network.
The modem must be in the off-line condition to change modes.
4.1.4. Sessions
In UDP and TCP PAD modes a session is open when there is an established “call” between the
modem and a client or server on the network (although UDP does not guarantee the other end is
on-line). When a session is open, the DART 300 modem is in on-line condition and the PAD is
active to send and receive data. When the “call” is terminated, the modem is off-line and the
session is closed.
The concept of a session in SLIP and PPP modes is distinct from that in UDP and TCP PAD
modes. From the DART 300 point of view, there is a SLIP or PPP session between the local host
and the modem, which does not extend across the CDPD network to remote clients or servers. To
the local host, there is a SLIP session with the modem and multiple client / server sessions with
remote terminals.
In all modes, when there is an open session, the modem is in on-line condition.
4.1.5. Transition Between States
On power-up the modem is normally in command state. Only if the Auto-dial on Start-up feature
(Section 5.3) is used will the modem transition to data state without the usual transition codes.
4.1.5.1. Command to Data State
The modem changes to data state when a session is opened either by dialling a client session or
answering a server session. When a session opens, the modem issues the CONNECT message
and asserts the DCD control signal.
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User’s Guide Local DTE/DCE Interface
CAUTION
Due to multi-processing in the modem, the DCD signal may be asserted slightly before
the modem has completed the transition to data state. The host device should allow a
delay of 500ms after receiving the CONNECT message and DCD signal before
beginning transmission or there may be some data lost.
Details
UPD and TCP sessions use the D ( Dial) command to open a client session. Se rver sessions are
opened when the modem auto-answers an incoming service request (S0=1) or the local host issues
the A (Answer) command to answer manually (when S0=0). With server sessions, the modem
first sends the RING result. When the modem answers, it issues the CONNECT result. Anything
coming from the modem after that is data from the remote station.
If Quiet is enabled (Q1) then the local host should allow the 500ms delay from the assertion of
DCD before beginning transmissions. For server sessions using Quiet, there are no messages from
the modem’s command processor; therefore all traffic from the modem can be considered data.
SLIP/PPP connections issue either D (Dial) or O (On-line) commands to open a session. The
host’s stack then manages client and server activities. The modem issues CONNECT and asserts
DCD for the transition to data state, just as it would for UDP and TCP sessions.
If the host has escaped from data state and kept the modem in on-line condition, it can return to
data state with the O (On-line) command. The modem will repeat the CONNECT message for
the transition to data state. DCD will have remained asserted to indicate that on-line condition
(the open session) was retained thro ughout.
4.1.5.2. Data to Command State
When the modem changes to command state, there will be an OK result issued. This may be
preceded by another result (such as NO CARRIER) to indicate that the session was closed by an
event outside the modem. A closed session requires the modem to return to command state.
NOTE
A transition to command state from data state does not require that the session be
closed. This means that DCD will remain asserted while the modem is in command
state, on-line condition.
Details
Several events can cause the modem to transition from data to command state based on mode.
UDP and TCP PAD mode transitions:
• The modem receives the Time Dependent Escape Sequence (TDES) (Section 6.6.3.1)
• The modem receives the Time Independent Escape Sequence (TIES) (Section 6.6.3.2)
• DTR is de-asserted, with a configuration to use DTR (&D1 or &D2).
• The UDP or TCP PAD Session Timeout (S30) expires due to inactivity on the connection.
• The remote terminal closes the session (TCP closing handshake).
• The modem is reset or power-cycled (and is not using auto-dial).
SLIP mode transitions:
• DTR is de-asserted, with a configuration to use DTR (&D1 or &D2).
• The modem receives the escape sequence as a SLIP frame (0xC0 +++ 0xC0)
• The modem is reset or power-cycled.
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