Quectel EC200U Series Installation and operating instructions

EC200U&EG915U Series
PPP Application Note
LTE Standard Module Series
Version: 1.1
Date: 2021-08-17
Status: Released

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About the Document
Revision History
Version
Date
Author
Description
-
2021-04-16
Baron ZHENG
Creation of the document
1.0
2021-05-10
Baron ZHENG
First official release
1.1
2021-08-17
Baron ZHENG
Added an applicable module series EG915U.

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Contents
About the Document...................................................................................................................................3
Contents.......................................................................................................................................................4
Table Index...................................................................................................................................................5
Figure Index.................................................................................................................................................6
1Introduction..........................................................................................................................................7
2PPP Application Mode.........................................................................................................................8
3PPP Setting...........................................................................................................................................9
3.1. General Procedures for PPP Setting...........................................................................................9
3.2. Recommended Procedures for PPP Setting.............................................................................10
4PPP Connection Modes.....................................................................................................................12
4.1. Data Mode and Command Mode...............................................................................................12
4.1.1. Switch from Data Mode to Command Mode..................................................................12
4.1.1.1. Change DTR Level to Switch from Data Mode to Command Mode......................12
4.1.1.2. Use Sequence +++ to Switch from Data Mode to Command Mode......................12
4.1.2. Switch from Command Mode to Data Mode..................................................................13
4.1.2.1. UseATO to Switch from Command Mode to Data Mode.......................................13
4.2. Handle URC in Data Mode ........................................................................................................13
4.3. Data Carrier Detection (DCD) Mode..........................................................................................13
5PPP Connection Termination...........................................................................................................15
6PPP Dial-up Operations.....................................................................................................................16
6.1. Preparation.................................................................................................................................16
6.2. PPP Dial-up in Windows 10.......................................................................................................16
6.2.1. Modem Configuration.....................................................................................................16
6.2.1.1. Add a New Modem.................................................................................................16
6.2.1.2. Configure the Modem Driver ..................................................................................21
6.2.2. Dial-up Network Configuration.......................................................................................22
6.2.2.1. Create a New Connection ......................................................................................22
6.2.2.2. Configure the Connection.......................................................................................24
6.2.2.3. Configure the Dial-up Tool......................................................................................25
6.2.2.4. Establish the Dial-up Connection...........................................................................26
7Appendix References........................................................................................................................27

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Table Index
Table 1: Related Documents...................................................................................................................... 27
Table 2: Terms and Abbreviations.............................................................................................................. 27

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Figure Index
Figure 1: PPP Application Mode ..................................................................................................................8
Figure 2: General Procedures for PPP Setting............................................................................................ 9
Figure 3: Flowchart of Recommended Procedures for PPP Setting......................................................... 10
Figure 4: Search for “Phone and Modem”in Control Panel ...................................................................... 17
Figure 5: Add a New Modem......................................................................................................................18
Figure 6: Select Model of the Modem........................................................................................................19
Figure 7: Select a Port ...............................................................................................................................20
Figure 8: New Modem is Installed Successfully ........................................................................................20
Figure 9: Configure the Modem Driver.......................................................................................................21
Figure 10: Create a New Connection......................................................................................................... 22
Figure 11: Set up the New Connection...................................................................................................... 23
Figure 12: Configure the Connection......................................................................................................... 24
Figure 13: Configure the Dial-up Tool........................................................................................................ 25
Figure 14: Connecting to Dial-up Connection............................................................................................26
Figure 15: Establish the Dial-up Connection Successfully........................................................................ 26

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1Introduction
This document briefly introduces the PPP functions of Quectel’s EC200U and EG915U series modules,
including PPP application modes, setting procedures, connection modes, termination steps and dialing
examples.

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2PPP Application Mode
The usage of PPP (Point-to-Point Protocol) is illustrated in the following figure. Use UART port or USB
port for PPP connection. The module provides a PPP server for application, and the application provides
a PPP client for the module. Meanwhile, the application must provide protocols such as TCP/IP, HTTP(S),
etc. When PPP connection is established, the IP packet data stream from the application will be
transmitted to the Internet through the module.
Most standard operating systems (e.g. Windows, Unix/Linux) include the PPP protocol stack. For
operating systems that have no available applications for PPP connection, it is necessary to develop
applicable application software first.
UART
USB
UART
USB
PPP
IP
Application
PPP
Radio Bearer
IP RELAY
Module
Application
TXD
RXD
CTS
RTS
DTR
DCD
RING
TXD
RXD
CTS
RTS
DTR
DCD
RING
USB_DM
USB_DP
USB_GN
USB_VBUS
USB_DM
USB_DP
USB_GND
USB_VBUS
Figure 1: PPP Application Mode

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3PPP Setting
3.1. General Procedures for PPP Setting
After the module registers on GPRS network, it is necessary to set the APN for PPP by AT+CGDCONT
and to start PPP by ATD*99#. After executing ATD*99#, the module will enter the PPP frame interaction
process, which is based on standard PPP protocol. The module data packet interaction description is
shown in the figure below. For more details about standard PPP, see RFC 1661.
AT+CGREG?
+CGREG:0,1
AT+CGDCONT=1,"IP","CMNET"
OK
ATD*99#
7E FF 7D 23 C0 21 7D 21 7D ……
TE MT
CONNECT
Figure 2: General Procedures for PPP Setting

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3.2. Recommended Procedures for PPP Setting
Connect_Count
< 5
Power on the
module
AT+CPIN?
Query (U)SIM
card status
AT+CGREG?
Query PS network
1. Set APN by AT+CGDCONT
2. Start PPP dialing by ATD*99#
Return CONNECT
MCU got IP and
DNS
Data transmission
MCU sends
PPP
Terminate-
Request
packet
Connect_Count++
Recommended Power-on/off:
For details of the recommended
power-on/off methods of each
applicable module, see their
Hardware Design documents
respectively.
Exit from the PPP dialing if (U)SIM
card is not ready in 20 s.
(U)SIM card is ready
Query (U)SIM Card Status:
AT+CPIN. Reboot the module if it
fails to detect (U)SIM card in 20 s with
AT+CPIN?.
APN Configuration:
1. APN must be set by
AT+CGDCONT.
2. Use AT+CGACT? to check
whether the current context has been
activated when AT+CGDCONT
returns error.
Y
Y
N
Packet Interaction:
1. Exit from the procedure of Packet
Interaction by +++.
2. The module will report NO
CARRIER when PPP connection is
terminated.
LCP Negotiation:
1. If UART is used, ensure the baud
rate between MCU and the module is
the same.
AUTH Negotiation:
1. Ensure the type of AUTH is one of
the following two: PAP(0xc023),
CHAP(0xc223).
IPCP Negotiation:
1. Check whether MCU has got legal
IP and DNS address.
2. Check whether the amount of DNS
MCU is equal to the amount
requested by MCU.
3. Terminate PPP connection if IPCP
negotiation between TA and TE is not
completed in 90 s, and then retry PPP
setup.
Exception Handling:
1. Check whether the PPP Terminate-
Request packet is right.
2. Reboot the module if the steps
above do not work.
Start timer when
IPCP negotiation
begins
Succeed to
negotiate IPCP in
90 s
Y
NMCU receives
PPP Terminate-
Ack packet in 3 s
Send Count
< 5
Exception handling
Send Count++
LCP negotiation
AUTH negotiation
IPCP negotiation
Packet Interaction
OK
OK
OK
N
Y
Y
N
N
1. Synchronization between TE and TA.
2. Fix and save baud rate by AT+IPR=xxx&W. If
USB modem port is used, this could be ignored.
Network:
1. It indicates that the module has
registered on network when
AT+CREG? returns 1 or 5.
2. Reboot the module if it fails to
register on network in 60 s.
Exit from the PPP dialing if
the module fails to register
on network in 60sAT+CREG?
Query network
status
Register on network in 60 s
PS Network:
1. It indicates that the module has
registered on PS when AT+CGREG?
returns 1 or 5.
2. It is able to go to next step without
registering on PS in 60 s.
Figure 3: Flowchart of Recommended Procedures for PPP Setting

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When the module is powered on, if the main UART is used, set the baud rate by executing
AT+IPR=xxx;&W. Before executing ATD*99# to set PPP, you must check the status of the (U)SIM card
by AT+CPIN?. When the (U)SIM card is ready, please periodically check the network registration status
by AT+CREG? and AT+CGREG? until the network is prepared.
1. Please ensure MCU and the module are synchronized successfully after rebooting the module. MCU
sends AT<CR><LF> to the module every 100 ms until it receives OK reported by the module. If the
main UART is used, the MCU will execute AT+IPR=xxx;&W to set and save the baud rate after
successfully synchronizing the baud rate.
2. Before inputting the next AT command, the MCU needs to wait for the response to the previous AT
command (such as response OK, CME error, CMS error). If there is no response within 60 seconds,
the module can be restarted.
3. It is strongly recommended NOT to power on/off the module frequently. If 3 consecutive dialing retries
fail, you can immediately power on/off (reset) the module for the first time.After resetting, if the dialing
retry fails, you need to wait 10 minutes for the second reset, 30 minutes for the third reset, and one
hour for the fourth reset.
4. If the MCU fails to transmit data to network after establishing the PPP connection, please check the
PPP configuration and network status and restart the module.
NOTES

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4PPP Connection Modes
4.1. Data Mode and Command Mode
The module communicates with application via USB or UART port (including AT commands and data).
USB and UART ports have two working modes: data mode and command mode.
The two ports are in command mode before PPP is set, and the module can executeAT commands in this
mode. When PPP negotiation is started, the two ports enter data mode, and remain in the mode when the
PPP connection is set. If the PPP connection is not successfully established, the two ports will be in the
command mode. In data mode, the module cannot execute AT commands.
EC200U and EG915U series modules provide convenient methods to switch between the two modes.
4.1.1. Switch from Data Mode to Command Mode
4.1.1.1. Change DTR Level to Switch from Data Mode to Command Mode
When the PPP connection has been established and USB/UART port is in data mode, change the DTR
level from low to high to switch from data mode to command mode (AT&D1 must be executed first). After
the switch is successful, the module will return OK.
4.1.1.2. Use Sequence +++ to Switch from Data Mode to Command Mode
After the PPP connection is successfully established, use +++ to switch the USB/UART port from data
mode to command mode. To prevent the +++ escape sequence from being misinterpreted as data, the
following requirements should be followed:
1) Do not input any characters within 1 s or longer before inputting +++.
2) Input +++ within 1 s, and no other characters can be inputted during this period.
3) Do not input any characters within 1 s after inputting +++.
When +++is received, the USB/UART port will switch from data mode to command mode, and the
module will return OK.

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Please perform the above operations after completing the PPP negotiation, otherwise the above
operations will terminate the PPP negotiation and the USB/UART port will exit the data mode. After
completing the PPPnegotiation, when the USB/UART port switches to the command mode, the input data
will be treated asAT command, and the module maintains the PPP connection.
4.1.2. Switch from Command Mode to Data Mode
4.1.2.1. Use ATO to Switch from Command Mode to Data Mode
To switch USB/UART port from command mode to data mode when PPP connection maintains, you can
execute ATO.
Example
//When PPP connection maintains, USB/UART port is in command mode.
ATO
CONNECT //Indicates that TA has entered data mode, and all data inputted from USB/UART
port will be treated as PPP frames.
4.2. Handle URC in Data Mode
The URC for incoming calls and short messages in data mode will not be reported to the PPP dial-up port
during PPP connection. But the level of module’s RI pin will change from high to low for 120 ms as an
indication of URC for incoming calls and short messages. The MCU can switch the port to command
mode according to the RI pin status to process incoming calls or short message. After switching to
command mode, the URC will be reported to the PPP dial-up port if there are still incoming calls or text
messages.
4.3. Data Carrier Detection (DCD) Mode
DCD mode is determined by AT&C. If AT&C0 is executed, the DCD pin will not be used to indicate the
data carrier status. While executing AT&C1, the DCD pin will be used to indicate the data carrier status.
The pin will remain at low level when there is data carrier or PPP negotiation begins, otherwise it will
remain at high level.
NOTE

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When switching module’s USB/UART port from data mode to command mode (by using +++), the DCD
state remains unchanged.
NOTE

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5PPP Connection Termination
There are two methods to terminate the PPP dial-up connection:
1. Terminate the PPP connection through the LCP Terminate-Request message, and this method is
recommended.
2. TA can also terminate the PPP connection by changing the DTR level. Set the DTR function by
AT&D2 first, change the DTR level from low to high, and the data connection will be automatically
terminated. After the PPP connection is completely terminated, the USB/UART port will enter the
command mode. Examples are as follows:
Example
//USB/UART port is still in command mode before PPP connection is established.
AT&D2
OK
1. PPP connection termination procedures must be performed in data mode.
2. PPP connection termination procedures can be performed at any time during the PPP setting or
connecting process.
NOTE

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6PPP Dial-up Operations
This chapter introduces how to establish PPP dial-up in Windows 10. For detailed operations in Linux
operating system, see document [3].
6.1. Preparation
It is necessary to finish the following steps before establishing a PPP dial-up connection in Windows.
1. Connect the module to PC and enter the PIN code if the (U)SIM card PIN is locked.
2. Make sure the (U)SIM card can successfully register on GPRS network.
6.2. PPP Dial-up in Windows 10
6.2.1. Modem Configuration
6.2.1.1. Add a New Modem
If the Standard 19200 bps Modem is not installed, you need to add a new standard modem to the
modem section of the control panel.

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1. Search for “Phone” in the main interface, and then click “Phone and Modem”as follows when it
appears:
Figure 4: Search for “Phone and Modem”in Control Panel

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2. Double-click the “Phone and Modem”, and select “Modems” →“Add…” to add a new modem, as
shown in the following figure.
Figure 5: Add a New Modem

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3. Follow the instructions on the screen to install the new modem: select “Standard 19200 bps
Modem”and then the port (such as “COM10”) to be installed; click “Next”button until the
configuration is complete. For details, see the figure below.
Figure 6: Select Model of the Modem