Objective

This application note provides a guide on configuring and verifying the operation of up to 10 remote TCP/IP data sockets, enabling connections to multiple remote devices using Siretta’s ZETA range of industrial modems.

A TCP/IP data socket, often simply referred to as a socket, is a software endpoint that enables communication between two computers or devices over a TCP/IP network. It is a fundamental component for establishing network connections and data transfer. Sockets are identified by a combination of an IP address and a port number, allowing data to be sent and received over the network between these endpoints.

All configurations are controlled using simple Attention commands. AT commands are a set of instructions used to communicate with and control modems.

Solutions

Resources used:

• ZETA-NLP-LTE1 (EU) Starter Kit. (Although any ZETA starter kit is compatible)
• ZETA-xxP Quick Start Guide
• Initial Modem Setup Guide App Note
• SIM card with a fixed public IP address
• A PC with an installed Terminal Emulator program
• AT command reference manual for ZETA-NLP-LTE1 (EU)

Modem Configuration:

1. Refer to the ZETA-xxP Quick Start Guide, which provides step-by-step instructions for initialising the modem and establishing a connection with Tera Term.
2. Verify the network registration state by executing the AT command: AT+CREG?
3. The modem will respond with one of the following when registered:
   1. +CREG: 0,1 – Registered to a home network
   2. +CREG: 0,2 – Not registered, but is currently searching for an operator to register to
   3. +CREG: 0,3 – Registration denied
   4. +CREG: 0,5 – Registered to a roaming network
4. Associate a socket with a Packet Data Protocol (PDP) context using the following AT commands:
   1. AT#SCFG=(1-10),(1-16),(0-1500),(0-65535),(10-1200),(0-264)
   2. AT+CGDCONT=1,”IP”,”APN Name”
   3. AT#SGACT=1,1,”APN Username”,”APN Password”

NOTE: Highlighted text refers to parameters that are user specific.

In this instance, APN Name, Username, and Password are variables that would differ from one user to another, depending on their respective SIM card network operator.

In this app note the APN Name “wlapn4.com” along with the username and password “OLANCHAG” are specific to Siretta test SIM’s. It’s worth noting that not all network operators require an APN username and password. In such a case, leave these fields blank. The command would be: AT#SGACT=1,1

See commonly used public APN details via the following link:

Common Global APN Settings for M2M Cellular Modems

PDP context profile 1 is the system’s standard default. To activate it, at least one socket must be associated with it. Issue the command AT#SCFG=

The format of the command response will follow the structure: <Socket ID>,<PDP Context>,<Packet size>,<Socket inactivity timeout>,<Connection timeout>,<Data send timeout>

To activate a context other than the default, first, associate a different socket to it.

The results of the #SGACT AT command will yield the fixed IP address assigned by the network operator. For the SIM used in this app note that is: 10.127.93.4.

5. Verify the socket configurations using AT command AT#SCFG?

6. Check the firewall setting by issuing the AT command AT#FRWL? (By default the firewall is enabled and configured to reject all incoming socket connections.)

7. The command response “OK” indicates that the firewall will not allow any incoming socket connections. To allow incoming socket connections issue the AT command: AT#FRWL=1,”X.X.X.X”,”Y.Y.Y.Y” where:
a. X.X.X.X represents the permitted incoming IP address
b. Y.Y.Y.Y represents the permitted subnet mask.

8. Typically, an IP address is associated with a default subnet mask determined by its class. There are three main classes: Class A, intended for extensive networks; Class B, for medium-sized networks; and Class C, designed for smaller networks. For more detailed information, refer to the provided link.
https://learn.microsoft.com/en-us/troubleshoot/windows-client/networking/tcpip-addressing-and-subnetting

9. The “Allowed incoming IP address” is configured as “10.127.93.4,” signifying permission for the specific network address 10.127.93.4. Whilst the “Allowed subnet mask” is configured as “255.255.255.0,” indicating authorization for any IP within the 10.127.93 subnet (Only incoming connections from 10.127.93.1 to 10.127.93.254 will be allowed)

10. To configure the firewall to allow only one specific IP address the subnet mask should be set to 255.255.255.255.

11. To disable the firewall completely, issue the AT command: AT#FRWL=1,”0.0.0.0”,”0.0.0.0”

NOTE: Disabling the firewall completely is not advised if integrating a Siretta Modem into an end application. For security purposes the firewall MUST not be disabled on production systems.

Opening a Socket Connection

To establish an outgoing connection, a listening socket must be created. It will then be bound to the IP address and a user-selected port number. The ZETA modem used in this app note provides support for a maximum of 10 sockets total. The TCP ports can fall within the range of 1 to 65,535.

TCP ports are categorised into different types. These port types help identify and manage network traffic efficiently.

• Well-Known Ports (0-1023): These ports are reserved for system services and well-known protocols.
• Registered Ports (1024-49151): Registered ports are used by various applications and services that are not part of the well-known category but still require standardization.

It’s worth noting that certain well-known ports may be subject to blocking on certain networks, consequently, it is recommended to select port numbers above 49152 as they are less likely to face restrictions. For more detailed information, refer to the provided link. https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers

Issue the AT command: AT#SL=N,1,(1 – 65535) Where N represents a socket number between 1-10.

1. Open listening socket 1 for TCP on Port 10
2. Open listening socket 2 for TCP on Port 200
3. Open listening socket 3 for TCP on Port 3000

4. Check the socket status by issuing the AT command AT#SS. This command shows all open sockets. For checking status of individual sockets issue the command AT#SS=N Where N is the socket number.

The format of the command response will follow the structure: <Socket ID>, <State>,<IP>,<Port number>

Testing The Socket Connection

1. Open Tera Term on an internet enabled PC, alternatively, using the same PC open a second Tera Term window.
2. Configure the terminal as shown below, remembering to replace “TCP port#” and “Host” with the selected port number and IP address respectively.
3. Select “Other” under Service.

4. Click OK
5. Observe for an incoming socket connection “SRING: N” within the terminal window.
6. Accept the incoming connection by issuing the AT command AT#SA=N,1
7. An OK response will be sent when a connection is successful.
8. Socket connection N is now established.

Sending Data to a Connected Socket

1. To send data to the socket issue the AT command AT#SSEND = <Socket ID>
2. Once the command has been issued, the terminal will present an angled bracket. “> “ Enter any data wish to be sent after the bracket.
3. To send press “Ctrl-Z”
4. An OK response will be sent if successful.
5. The data will appear in the second terminal window.

Receiving Data from a Connected Socket

Data must first be entered within the terminal window of the remote connection.

Issue the following AT command from the modem to receive data from a remote socket.
AT#SRECV = <Socket ID>, <maxByte>[,<UDPInfo>] NOTE: Square brackets denote optional parameter(s)

NOTE: If AT#SRECV is issued when there is no data present in the buffer, the command will return an ERROR.

To read 40 bytes of data from socket 1 issue the AT command AT#SRECV =1,40

The example below shows 34 bytes of data have been read from socket ID 1.

Checking Data Traffic from a Connected Socket

Issue the AT command AT#SI=<Socket ID>, the format of the command response will follow the structure:

<Socket ID>,<Data sent>,<Data received>,<Buff_IN>, <ack_waiting >,<Cause>

For information on all data sockets, issue the AT command AT#SI

In conclusion, following the outlined steps leads to the successful establishment of a connection and enables the transmission of data from the host to the receiver.

Additional Reading

The post Establishing Multiple Socket Connections with Siretta’s ZETA Modems appeared first on Siretta Limited.

This application note is produced for customers who may wish to develop their own application to run on Siretta Modems using AppZone C.

What is AppZone C?

AppZone C is a software layer that provides a set of APIs to access the modem. AppZone C allows the user to create M2M applications that run on the module CPU; eliminating the need to use an external application processor.

All Siretta modems support APPZone C, except Siretta SL500 which already runs an application to act as an RS232 serial gateway. https://www.siretta.com/products/industrial-modems/lte-cat-1-mobile-network/low-power-lte-cat-1-rs232-gateway/

This guide covers different aspects of programming Siretta Modems, including how to Open a new Project, build the project, load it and run the application.

The sample application used “General_Info”.

“General_Info” gives general modem information such as, IMEI, FW version etc. It also gives information on registration and debug prints on the main UART.

Requirements

• Window PC with Java Version 8 or above (64-bit) (Java can be installed from the following link Java | Oracle)
• Window PC with Java (TM) SE Development Kit Version 20 or above (64) , JDK can be downloaded from the following link Download the Microsoft Build of OpenJDK | Microsoft Docs
• Window PC with Code Editor application such as  UtraEdit, Sublime or NotePad++ (NotePad++ can be downloaded from Download Notepad++ v8.5.2 | Notepad++ (notepad-plus-plus.org)
• Window PC with Tera Term Version 4.96 (Tera Term can be downloaded from the following link – Teraterm Link).
• IoT AppZone IDE V5 (IoT AppZone IDE V5 can be downloaded from the following link IoT App Zone Developer Resources – Telit )
• Window PC with A Telit AT Controller ( Telit AT Controller can be downloaded from the following link IoT App Zone Developer Resources – Telit )
• Siretta Part ZETA-NLP-LTE1 (EU) (A Low Power Modem with RS232 and USB serial ports) was used for this application note. Product link: Ultra Low Power LTE Cat 1 (EU) – Siretta – Enabling Industrial IoT
• Initial Modem Setup Guide Application Note: https://www.siretta.com/2019/08/basic-modem-functions/
• Enhanced Modem Functions – https://www.siretta.com/2023/02/enhanced-modem-functions/

1. Install all the above applications on your PC.
2. Open the PC control panel to check all the applications have been installed.
3. Confirm Java and Java (TM) SE Development kit are installed (See below).

4. Confirm Notepad++ (64 bit) is installed or code editor of your choice ( See below).

5. Confirm Tera Term Version 4.96 or above is installed (See below).

6. Confirm IoT AppZone IDE V5 or above is installed (See below).

7. Confirm Telit AT Controller is installed (See below).

Note: Now your PC have all the required applications for programming Siretta Modem.

8. Follow pages 1 to 5 of the Initial Modem Setup Guide Application Note.
9. Issue the AT commands shown in points 10-13 below to gather more information about the Siretta modem.
10. Issue ATI4 – To obtain: Cellular Module Model.
11. Issue AT+CGSN – To obtain: Cellular Module IMEI number.
12. Issue AT+CGMI – To obtain: Manufacturer of the cellular Module.
13. Issue AT#SWPKGV – To obtain: Software Package Version inside the Module.
14. You will receive the conformation as shown below.

Note:The modem information above is very important, as it allows the user to choose and use the right tool chain for compiling an application.

15. Disconnect the modem from Teraterm.
16. Open Telit- IoT AppZone IDE V5 by double clicking its desktop icon or through start >>program>> Telit- IoT AppZone IDE V5. You will be presented with a screenshot below.

17. Leave a default Workspace “telit- workspace”.
18. Click “Launch” tab.
19. Wait for workspace to load.
20. You will be presented with a screenshot as below.

21. Click “File”
22. Select “New “ from dropdown menu.
23. Select “Telit Project”

24. You will receive the screenshot below.

25. Type the Project Name of your choice ( For this Guide “General_INFO” was used).
26. Check “Use default location box “ if not checked.
27. Choose the Product you wish to program from the dropdowm menu below.

28. For this guide the Siretta Modem with Telit “Module LE910C1-EU” was used ( See step 14 above).
29. Select “LE910Cx “ from the list.

Note: Information about Environment, Toolchain and firmware are auto polulated when product to be programmed “ LE910Cx” is selected.

30. Confirm that a firmware returned in step 14 above is compatible with the format in step 24 above , otherwise the user may have to upgrade the device to the latest version using a SPARKTool which can be dowloaded from the following link SirettaSPARK Tool.
31. Confirm that your page looks like that shown below:

32. Click “Next”
33. Screenshot below will appear.

34. From the dropdown menu, Select “Example template “

35. Select “AppZoneSampleApps- MAIN_UART”in Sample applications.

36. In “Sample applications”, double click “AppZoneSampleApps- MAIN_UART” to expand the selection
37. From here, select “General_INFO”
38. You will be presented with a screenshot like the one below.

39. Click “Finish”
40. You will be presented with a progess bar as seen below.

41. Wait for the operation to complete.
42. Once the operation is completed you will be presented with a screenshot as below.

43. Click “General_INFO” to select.
44. Expand “General_INFO” by clicking “>”
45. You will be presented with a screenshot below.

46. Expand “src” folder you will be presented with “M2M-main.c”

Note: M2MB-main.c is the main source code file which can be opened using text editor application to enter configuration details if required.

47. Collapse “src” folder.

48. Collapse “General_INFO”
49. Click to select “General_INFO”
50. Click Project
51. Select “Build All” from the project drop down menu.( See screenshot below).

52. If the build is successful, you will be presented with a screenshot as shown below without any errors or warnings.

53. Expand “General_INFO”
54. You will see a newly generated binary file shiwn as “m2mapz.bin”

Note: binary file “m2mapz.bin” is the only file to be loaded to the Siretta Modem.

55. Click AZ C Console tab
56. You will be presented with a screenshot below.

57. Click Setting tab in red square above.
58. You will be presented with a screenshot like that shown below.

59. Select the COM Port where the Siretta Modem is connected, (for this guide COM12 Prolific USB-to-Serial Comm Port).
60. Select the default Baud rate of 115200
61. Parity: None
62. Data Bits: 8
63. Stop Bits: 1
64. Flow Control: Hardware Handshaking
65. Click: OK
66. Click: Connect com port icon “ ” to connect the Siretta Modem with AZC Console.
67. You will receive the screenshot shown below when a connection is succesfully made.

68. Drag the binary file “m2mapz.bin” and drop it to the space below:

69. You will receive the screenshot shown below when the application is successfully loaded to the Siretta Modem.

70. Start application by clicking the launch button
71. When successful you will receive a prompt that the application has “Started” then the application will run as shown below.

Note: You have successfully created, built , loaded and run an application to the Siretta Modem that returns Module information, including SIM information, registration information, cell ID, MCC ,MNC, and RSSI as seen above.

The Siretta modem will display the above information at each power up on its serial port, without the need to use any AT command. You may follow a similar procedure to that shown above to create different projects and run them.

Before you load a new binary to the modem you have to delete the previous one by following the procedure below.

72. Connect the Siretta Modem to the PC using the mini-USB to USB cable provided.
73. Open Telit AT Controller by double clicking desktop icon or through start>>Program>> Telit AT Controller
74. You will be presented with a screenshot like that shown below.

75. Click the “Settings” option above to see the screenshot below.

76. Confirm that the COM Port is directed to the Telit USB Modem. (For this Guide COM4 was used).

Note: For the Telit USB Modem to appear in a PC device manager, a  PC has to be  installed with USB driver and the Siretta Modem has to be connected to a PC using a mini-USB to USB cable. A USB driver can be downloaded from the following link: Software Library – Siretta – Enabling Industrial IoT – Software Updates

77. Leave the default settings Baud Rate at 115200, Parity None, Data Bits 8, Stop Bits 1 and Flow control set to off as seen above.
78. Click Connect.
79. You’ll receive the screen below when connection is successful.

80. Click “AT Terminal” icon above.
81. You will be presented with the screenshot below.

82. Expand “Cellular “ where you will then be presented with the option below.

83. Expand M2M_AppZone where you will be presented with the option below.

84. Click AT#M2MLIST
85. Click Execute

86. You will be presented with the screenshot below.

87. Click AT#M2MDEL = m2mapz.bin
88. Receive OK when Successful
89. You have successfully deleted the application “m2mapz.bin” from the Siretta Modem.
90. Now the Siretta Modem can be programmed with a different application.

Note: If user has their own application in binary file and wishes to load it to the Siretta Modem, then, the user can use AT Controller with the following AT commands AT#M2MWRITE=<filename>,<size>,<permission> then issue AT#M2MRUN=<mode>,”<file_name>”.

Siretta have tested all the AppZone C examples using this guide, so if you face any issues please contact support@siretta.com.

The post How to Program A Siretta Modem using AppZone C appeared first on Siretta Limited.

Objective

The NMEA 0183 standard defines an electrical interface and data protocol for communications between marine instruments. In IoT, however NMEA-0183 is mainly used by Satellite Navigation Systems to determine position, time, velocity and other information from a global positioning receiver.

This application note details the list of NMEA-0183 Sentences available from a Global Positioning Receiver, such as GPS, GLONASS and GNSS.

Examples of these products include Siretta’s QUARTZ Routers and ZETA Industrial Modems, equipped with GPS and GNSS.

All sentences conform to the NMEA-0183 version 3.01 format. All begin with $ and end with a carriage return and a line feed. Data fields follow comma (,) delimiters and are variable in length. Null fields still follow comma (,) delimiters, but contain no information. An asterisk (*) delimiter and checksum value follow the last field of data contained in an NMEA-0183 message.

Each sentence is explained using an example sentence and a description of what the sentence means.

NMEA-0183 sentences:

Each NMEA-0183 sentence has a specific function and provides a useful tool to the user in determining position, time, velocity and other useful data.

Below is a list of available sentences and their function. The following pages describe each sentence with a typical example and what each field means.

Sentence Descriptions:

Dynamic Positioning (DP):

An example of DP sentence/string is:

$PFUGDP,GN,033615.00,3953.88002,N,10506.75324,W,13,9,FF,0.1,0.1,149,0.1*13

Datum Reference Information (DTM):

DTM sentence identifies the Datum.

An example is:

$GPDTM,W72,,0.0,N,0.0,W,0.0,W72*7D

GNSS Satellite Fault Detection (GBS):

Example:

$GPGBS,015509.00,-0.031,-0.186,0.219,19,0.000,-0.354,6.972*4D

Time, Position and Fix Data (GGA):

Example:

$GPGGA,172814.0,3723.46587704,N,12202.26957864,W,2,6,1.2,18.893,M,-25.669,M,2.0 0031*4F

Position Data: Position Fix, Time of Position Fix, Status (GLL):

Example:

$GPGLL,3953.88008971,N,10506.75318910,W,034138.00,A,D*7A

GNS Fixed Data (GNS):

Example:

$GNGNS,014035.00,4332.69262,S,17235.48549,E,RR,13,0.9,25.63,11.24,,U,*70

GRS Range Residuals (GRS):

Example:

$GPGRS,220320.0,0,-0.8,-0.2,-0.1, -0.2,0.8,0.6,,,,,,1,*55

GPS DOP and Active Satellite (GSA):

Example:

$GNGSA,A,3,21,5,29,25,12,10,26,2,,,,,1.2,0.7,1.0*27

Position Error Statistics (GST):

Example:

$GPGST,172814.0,0.006,0.023,0.020,273.6,0.023,0.020,0.031*6A

Number of SVs in view, PRN, elevation, azimuth, and SNR (GSV):

Example:

$GPGSV,8,1,25,21,44,141,47,15,14,049,44,6,31,255,46,3,25,280,44*75

Note:

$GPGSV indicates GPS and SBAS satellites. If the PRN is greater than 32, this indicates an SBAS PRN, 87 should be added to the GSV PRN number to determine the SBAS PRN number.

$GLGSV indicates GLONASS satellites. 64 should be subtracted from the GSV PRN number to determine the GLONASS PRN number.

$GBGSV indicates BeiDou satellites. 100 should be subtracted from the GSV PRN number to determine the BeiDou PRN number.

$GAGSV indicates Galileo satellites.

$GQGSV indicates QZSS satellites.

Heading From True North (HDT):

Example:

$GPHDT,123.456,T*00

Leica Local Position and Quality (LLQ):

Example:

$GPLLQ,034137.00,210712,,M,,M,3,15,0.011,,M*15

MSK Receiver Signal (MSS):

Example:

$GPMSS,26.4,7.2,283.5,200,2*61

Time, Yaw, Tilt, Range, Mode, PDOP, and number of SVs for Moving Baseline RTK: (PTNL,AVR)

Example:

$PTNL,AVR,212405.20,+52.1531,Yaw,-0.0806,Tilt,,,12.575,3,1.4,16*39

Base Station Position and Position Quality Indicator (PTNL,BPQ):

Example:

$PTNL,BPQ,224445.06,021207,3723.09383914,N,12200.32620132,W,EHT-5.923,M,5*

L Band Corrections and Beacon Signal Strength and related information (PTNL,DG):

Examples:

For beacon DG message: $PTNLDG,44.0,33.0,287.0,100,0,4,1,0,,,*3E

For L-band DG message: $PTNLDG,124.0,10.5,1557855.0,1200,2,4,0,3,,,*3C

Evant Marker Data (PTNL,EVT):

Example:

$PTNL,EVT,221212.000008,1,5026,1893,1,17*4F

Time, Position, Position Type and DOP Values (PTNL,GGK)

Example:

$PTNL,GGK,102939.00,051910,5000.97323841,N,00827.62010742,E,5,09,1.9,EHT150.790,M*73

Note: The PTNL,GGK message is longer than the NMEA-0183 standard of 80 characters.

Time, Position, Position Type and DOP Values (PTNL,PJK):

Example:

$PTNL,PJK,202831.50,011112,+805083.350,N,+388997.346,E,10,09,1.5,GHT+25.478,M*77

Note:

The PTNL,PJK message is longer than the NMEA-0183 standard of 80 characters.

Projection Type (PTNL,PJK):

Example:

$PTNL,PJK,202831.50,011112,+805083.350,N,+388997.346,E,10,09,1.5,GHT+25.478,M*77

Note:

The PTNL,PJT message is longer than the NMEA-0183 standard of 80 characters.

Time, Locator Vector, Type and DOP Values (PTNL,VGK):

Example:

$PTNL,VGK,160159.00,010997,-0000.161,00009.985,-0000.002,3,07,1,4,M*0B

Heading Information (PTNL,VHD):

Example:

$PTNL,VHD,030556.00,093098,187.718,-22.138,-76.929,-5.015,0.033,0.006,3,07,2.4,M*22

Position, Velocity and Time (RMC):

Example:

$GPRMC,123519,A,4807.038,N,01131.000,E,022.4,084.4,230394,003.1,W*6A

Rate of Turn (ROT):

Example:

$GPROT,35.6,A*4E

Actual Track Made Good and Speed Over ground (VTG):

Example:

$GPVTG,140.88,T,,M,8.04,N,14.89,K,D*05

UTC Day, Month, Year and Local Time Zone Offset (ZDA):

Example:

$GPZDA,172809.456,12,07,1996,00,00*45

The post NMEA-0183 Sentences appeared first on Siretta Limited.

Objective

Power consumption is one of the key requirements of any Wireless IoT application.

A significant contributor to power consumption in such systems is the Cellular modem.

This application note shows how to set Siretta ZETA NLP modem in ultra-low power mode for reduced energy consumption.

Solution

ZETA-NLP Ultra Low Power Mode

The ZETA-NLP has a special mode of operation which forces the unit to drop down to an ultra-low power state where the modem is still operational and registered on the network but is functionally asleep. This allows for the modem to remain connected to the network and be ready to send and receive data using a fraction of the energy.

This ultra-low power state is achieved by setting the following AT command to the modem:

Ultra Low Power Control Signal

To control the power state of the modem from low power to ultra-low power it is necessary to use a special control signal in the RS232 serial port.
The control signal is called Data Terminal Ready (DTR) and is available on the RS232 serial port on pin 4 as shown in the table below.

Once the CFUN=5 command has been issued then the modem is ready to enter ultra-low power mode. To activate low power mode and put the modem in to a dormant state the DTR line must be de-asserted on the serial port. When the device has entered ultra-low power mode the CTS line will be de-asserted indicating that the device has gone into ultra-low power state. At this point the serial port is also deactivated, and the modem will not respond to AT commands and will appear to be OFF.

To bring the modem back to normal power state and communicate with the modem again it is necessary to assert the DTR line and the modem will leave its dormant state and become fully active again for normal operation. When in the dormant ultra-low power state an incoming call request or incoming SMS will force the modem to enter its full power mode and the modem is able to be used as normal.

This mode allows the modem to consume little current whilst it is not in use but be available for use locally by asserting the DTR line. The modem power ON and power lines will remain active throughout and can also be used to turn the modem completely OFF.

DTR Control Software

To control the DTR line on the modem and communicate with the AT command interface on the RS232 serial port it is necessary to use Terminal software which controls the DTR line. Siretta has tested the ZETA modem family with several terminal emulator applications which support DTR and RTS control signalling. Two recommended applications are shown below:

• Realterm (Download Link)
• Telit AT Controller

Ultra Low Power Receiving Data

In the ultra-low power state, a special provision must be catered for when data is received from a connected socket to be output over the serial port.

In this mode it is necessary to run the serial port in the following state:

1. Enable hardware flow control with AT&K3
2. Enable low power mode by issuing AT+CFUN=5
3. Setup a socket connection and establish an active connection
4. Enter ultra-low power state by de-asserting DTR control line
5. De-assert RTS line
6. Wait for specified timeout to check for incoming data

When the timeout has expired, to check for data over the connected socket follow the procedure below:

1. Assert DTR line to disable low power state and activate full serial port
2. Assert RTS line to receive full buffered data over serial port and wait for all data to be received
3. When all data has been received de-assert RTS line
4. De-assert DTR line to re-enter low power state and wait for the specified timeout to receive further data.

NOTE – While there is no data pending reception from the cellular network, the modem does meet the published low power consumption figures. However, if there is data pending from the cellular network, then the modem power consumption rises to approximately 5mA at 12V until the data transfer process has completed and low power state is re-entered. The modem does not automatically enter the full power state when there is pending cellular network data, so the connected application is required to periodically poll the cellular network. If there is pending data from the cellular network, this will immediately start to be received over the serial connection.

Once the data transfer is complete, the modem can be put back into the low power state where it will meet the published power consumption figures. The shorter the check interval, the less time will be potentially spent at the higher 5mA current consumption. The longer the check interval the less power will be used checking for received data from the network. Choose this check interval to match the requirements of your system.

Demonstration of Solution

Testing Ultra Low Power Mode using an Outgoing Socket Connection

NOTE – The siretta server is designed for test purposes only. For production applications the same process can be followed using your own configured server. The operation of the modem can be controlled locally, and the connected system can determine the optimum processing cycle for the application.

Ultra Low Power Incoming Data Process Cycle

Follow process flow below to receive incoming data over the cellular network when running in low power state where the timeout has expired, and data is ready to be received.

Check for data from the cellular network using the active connection.

>> Assert DTR
>> Assert RTS
< Receive incoming data >
>> De-assert RTS
>> De-assert DTR.

Wait for timeout to check for incoming data from the cellular network connection.

Additional Reading

The post Ultra Low Power Operation with a Siretta NLP Modem appeared first on Siretta Limited.

Objective

In some applications, the user may require the position of a system shown on Google Maps.

This application note shows how this can be done using a Siretta ZETA modem with GNSS capability.

This document shows how to convert Latitude Longitude to a position in the map.

Solution

GPS Location Integration into Google Maps

The GNSS engine in the ZETA modem will show the Latitude/Longitude position in Decimal Minutes format (ddmm.mmmm). However, Google Maps requires this information in Decimal Degrees format (dd.ddd). The solution is to convert position from one format to the other to show position on Google Maps.

The AT command AT$GPSACP will return the lat/long position information in the Decimal Minutes format.

GPSACP lat is in the format ddmm.mmmm

GPSACP lon is in the format dddmm.mmmm

Demonstration of Solution

Resources used:

• ZETA-GEP-LTE4 (EU) – including Cellular and GNSS antennas.
• ZETA-xxP Quick Start Guide
•  Initial Modem Setup Guide App Note 
• A PC with an installed Terminal Emulator program
• ZETA-xxP-LTE1 / ZETA-xxP-LTE4 AT Command Guide

Steps:

1. Follow the Initial Modem set up guide application note to communicate with the modem using AT commands.
2. Issue the following AT command AT$GPSP=1 to turn the GNSS engine ON in the modem.
3. Issue the AT command AT$GPSACP to obtain latitude and longitude

4. Stripping information’s from responses of AT$GPSACP.

UTC = 103709.000

Latitude = 5123.1355N

Longitude = 00058.4350W

HDOP = 9.5

Altitude = 96.0

Fix = 3

COG = 303.4

SPKM = 4.5

SPKN = 2.4

Date = 050224

Nsat_GPS = 03

Nsat_GLONASS = 02

Position Information Conversion

5. Obtaining Lat/Long

This position information can easily be converted into Google Maps compatible lat/long readings as shown below:

Strip the dd from the message i.e.

ddmm.mmmm

Which becomes

variable1 = dd
variable2 = mm.mmmm
variable3 = variable2 / 60

Rejoin values to make dd.dddd

dd.dddd = variable1.variable3

i.e. Latitude / Longitude for the Siretta office from NMEA GGA message to lat/long

Lat: ddmm.mmmm: 5123.1355 (N)
Lat: dd + mm.mmmm: 51 + 23.1355
Lat: dd + dd.dddd: 51 +( (23.1355 / 60) = 0.38559)
Lat: dd.dddd: 51.38559

Lat: 51.38559 (As this is north it is positive, south is negative)

Long: dddmm.mmmm: 00058.4350 (W)
Long: ddd + mm.mmmm: 000 + 58.4350
Long: ddd + dd.dddd: 000 + ((58.4350 / 60) =0.9739)
Long: ddd.dddd: 000.9739

Long: -000.9739 (As this is West it is negative, East is positive)

Latitude: 51.38559

Longitude: -000.9739

Display on Maps API

Now to get this into Google maps:

Go to http://maps.google.com.

Type the following in to the search box: 51.38559, -000.9739

Then hit ‘Search Maps’ and you get the Siretta office!!

For direct access to Google Maps use the URL below:
http://maps.google.com/maps?q=51.38559+-000.9739

Note:  AT command AT$GPSACP may return different parameters, depending on your location, date, time, number of available satellites and fix.

Additional Reading

The post GPS Latitude Longitude Conversion Guide for Google Maps appeared first on Siretta Limited.

Objective

Setup Dial-up Networking on Microsoft Windows

Solution

This application note describes the process to add the Siretta ZETA Modem as a Microsoft Windows Dial-up Adapter.

Demonstration of Solution

1. Find the Modem Tab in the PC’s Control Panel
2. Click Add
3. Check ‘Don’t detect my modem I will select it from a list’ and click ‘Next’
4. Select ‘Standard 56000 bps Modem’ and click ‘Next’
5. Select COM port Telit module is connected to and click ‘Next’
6. Highlight ‘Standard 56000 bps Modem’ and click ‘Properties’ (For Windows 7/10, click Change Settings)
7. Select ‘Advanced’ tab
8. In commands box type ‘AT+CGDCONT=1,”IP”,”yourAPNname”‘ without single quotes and select ‘OK’

You can view a list of common APN details here

Setting Up a New Connection Using the Newly Added Modem

The following steps describe how to set up a new connection on your newly added modem on Windows 7/10.

1. Navigate to > Start > Control Panel > Network and Sharing Center
2. Select ‘Connect to the Internet’ and ‘Next’
3. Click ‘Set up a new connection anyway’ and ‘create a new connection’
4. Select ‘Dial-up, connect using a Dial-up modem or ISDN’
5. Type ‘ *99***1# ‘ without the quotes for the Dial-up phone number
6. Enter Username and password which will be the ISP username and password
7. Type name for the connection and click ‘Connect’

You can view a list of common APN details here

The following steps describe how to set up a new connection on your newly added modem on Windows XP.

Setup Dial-up Networking on Linux OS

A number of tools are available to setup dial up adapters on Linux The command line based wvdial, or UI based NetworkAdmin or gnome-ppp can be used to setup the Siretta Industrial Modem for Dial-up networking. This procedure is based on gnome-ppp, however the basic configuration remains the same in all cases.

gnome-ppp

Install the latest version of gnome-ppp by typing the following command in the terminal window:
$sudo apt-get install gnome-ppp

Note: You must be logged in as sudoer or an administrator to execute this command.

Once the package has been successfully installed, type in the following command to execute the application $gnome-ppp

1. Click on setup from the main window.
2. Select the device and port (USB, SERIAL, etc) from the drop down menu and click on Detect.Gnome-ppp will check selected port for the modem and you will be prompted if it is not found
3. Set modem speed to 57600
4. Navigate to init settings
5. In the command box type and save the following command
6. AT+CGDCONT=1,”IP”,”yourAPNname”
7. Add the phone number *99***1#
8. Once the modem has been set up, a smaller window asking for username, password and phone number input will appear. Enter your username, password and *99***1# in the phone number box
9. Click on Connect

You will now be able to use the Siretta Industrial modem as a Dial-up adapter on your operating system by highlighting the name of your connection and clicking connect.

Additional Reading

The post Dial-up Networking using a Siretta Industrial Modem appeared first on Siretta Limited.

Objective

To send AT commands (or communicate) to a modem using a PC, the modem’s COM ports must be set to enable communication between the two.

A modem’s COM ports can be set using a terminal emulator. There are a number of terminal emulators available including, PuTTY, Hyperterminal , RealTerm  and TeraTerm. These programs are generally free to download.

Solution

This application note is intended to show how to set a modem’s COM port to communicate with a PC using Terminal Emulator Program of your choice.

List of Items:

A ZETA modem starter kit (includes power supply and RS232 cable for this application note)

Demonstration of Solution

1. Turn On the modem and connect it to a PC using the supplied RS232 cable
2. Open Hyperterminal (or your preferred terminal emulator)
3. Select new connection

4. Choose the correct COM port

5. Configure the port with the following settings:
• Bits per second: 115200
• Data bits: 8
• Parity: None
• Stop bits: 1
• Flow control: Hardware

6. Send AT commands to the unit

The OK response shows that the PC is communicating with the modem.

Additional Reading

The post Standard Modem COM Port Settings appeared first on Siretta Limited.

Objective

Once a Siretta ZETA modem is powered on, a combination of its 3 LEDs light up, showing different stages of modem connection to a network (default state).

Also, assuming the network connection is achieved, the modem can send a receive AT commands.

If any of the above fails to materialise, a troubleshooting procedure will help to investigate and solve basic issues.

Solution

This application note covers the following:

• No LED indication
• Modem keeps rebooting
• Failure to connect to a modem serial port
• No response from the modem when using AT commands
• No Carrier when dialling Voice/ data calls

Demonstration of Solution

LEDs Not Lit

• Check the modem has been connected to the correct power supply
• Check the power connector is inserted correctly
• Check the power has been switched on at the mains
• Check the LED functionality has been set with either AT#SLED or AT#GPIO AT commands

Modem Reboot

If your Siretta modem keeps rebooting, please check the following procedures:

• Check the SIM card has been inserted correctly
• Check the power supply is correctly specified or you are using an approved Siretta PSU.

No Serial Connection

If your Siretta modem has no serial connection, please check the following procedures:

• Check the serial cable has been inserted correctly
• Check the serial cable has the correct pin alignment (see below)
• Check the modem emulator program has the proper settings (Factory settings = 115200, 8, n, 1)
• Check there isn’t another program interfering with the communication program
• Check there isn’t a conflict with communication port access

RS232 Serial Port Interface

This connector provides serial RS232 communication between ZETA-xxP modem and the connected equipment. The modem can be configured via the RS232 connection using AT commands as specified in the AT command manual.

Table 15. Pins Usage

No Carrier Message

If your Siretta modem returns a ‘No Carrier’ message upon an attempted call (voice or data), please consider the following possible causes:

Additional Reading

The post Modem Troubleshooting appeared first on Siretta Limited.

In the cellular network GSM (2G) and UMTS (3G) use circuit switching for voice, circuit switched dialup (CSD) and short messaging service (SMS) traffic and use packet switching for GPRS data traffic. In LTE (4G) the entire network uses packet switching and has no capability for circuit switched network support. As a result, the voice and SMS services must be moved over to a packet switched network when using the LTE (4G) network. In addition to this, CSD is no longer supported and GPRS data must be used instead.

Please see ‘Circuit Switched Dialup (CSD) Migration to LTE Application Note’ here.

Voice Overview

Many applications in use today utilise voice as part of the service offering. This may be to connect two parties together to communicate such as in an elevator emergency failure system, to implement an automated payment service using a dial keypad or report a fault with a system using normal spoken language. Whatever the reason for using the voice service in a cellular system, there are some differences with the LTE network which are described in more detail below.

On legacy devices supporting GSM (2G) and UMTS (3G) services, the voice and SMS components of the system use circuit switching as the transmission channel. For GSM the whole system was built on an analogue infrastructure and digital data was added to the system later with the advance of GPRS packet data. The UMTS system is based on the GSM standard and therefore also supports both digital and analogue components. The UMTS framework allows much higher data rates over GSM but is still based on a similar infrastructure.

LTE on the other hand is entirely digital and has no analogue components at all. Therefore, new methods are used to take advantage of the new features offered by the LTE network as analogue voice calling is no longer possible and the packet switched network must be adopted.

VoLTE (Voice over LTE) Overview

The LTE network supports voice and many other additional services in the same way as GSM and UMTS, however, as there is no analogue component the voice must be encoded and sent digitally across the network using packets. The 3GPP body have specified the voice service on LTE which is highly optimised and takes advantage of the additional bandwidth and low latency of the LTE network. This service is called Voice over LTE (VoLTE) and uses the digital packet switched network in a much more efficient way than traditional services. This means that VoLTE can support up to 3 times more voice capacity than previous UMTS networks and up to 6 times more capacity than older GSM networks.

The VoLTE service is provided on LTE over the IP Multimedia System (IMS) network service which is a standardized framework for delivering multimedia services over TCP/IP. It has been developed to allow all content rich media from wireless and wireline applications and allows for advanced services to be provided over the existing infrastructure without the need for individual control functions for each service.

The network provider must support IMS to be able to offer VoLTE as a service to its customers. The IMS framework must be integrated within the network’s core architecture and is fundamental to the operation of the network.

Network Usage with Circuit Switch Fall Back (CSFB)

With existing GSM (2G) and UMTS (3G) networks, the core functions are built into the application and can be supported with any hardware platform that supports voice and any SIM card that supports voice. This allows for a very simple implementation and calls can be established without any special configuration to the end equipment.

With newer modems that support LTE (4G) in addition to GSM (2G) and UMTS (3G) the firmware in the modem performs a subtle trick to continue having seamless voice support. When connected to the network for transmitting digital packet data, the unit connects to and uses the LTE network. When attempting to dial a voice number the unit automatically switches to UMTS (3G) or GSM (2G) to establish the call. Once the call is finished it reverts to the LTE network. This technology is called circuit switch fall back and is a short-term solution to allow all network providers to offer voice services on the LTE network whilst they implement their own full IMS solution.

This process is fine whilst there are UMTS (3G) and GSM (2G) networks available to use but the analogue networks are being gradually sunset to be replaced entirely with the LTE network.

With the LTE (4G) network it is necessary to configure the device to allow calls to be made using the LTE only network over the IMS service.

SMS Overview

The short messaging service (SMS) can be used to send and receive small text messages which can be used in a variety of ways for applications that use the cellular network. The messaging service can be used to configure settings in remote equipment as well as reporting on the current configuration. In addition, the messaging service can inform users directly of a triggered alarm state or indicate when a certain criterion has been met. As with voice, the existing GSM (2G) and UMTS (3G) core functions are built into the system and can be supported with any hardware platform that supports the SMS messaging service and any SIM card that has SMS functionality enabled. This allows for a simple implementation and messages can be sent and received without any special configuration to the end equipment.

With newer modems that support LTE (4G) in addition to GSM (2G) and UMTS (3G) the firmware in the modem supports circuit switched SMS (using the analogue network) and packet switched SMS (using the digital network) offering seamless SMS support. The unit can be configured to send packet switched SMS when connected to the LTE network for transmitting digital packet data by selecting appropriate configuration option. Alternatively, the unit can be configured to send SMS via the circuit switched network. When attempting to send an SMS via the circuit switched network, the unit automatically switches to UMTS (3G) or GSM (2G) from LTE (4G) to send the SMS. These options are described in more detail later.

This process works perfectly whilst there are UMTS (3G) and GSM (2G) networks available to use but the analogue networks are being gradually sunset to be replaced entirely with the LTE (4G) network.

With an LTE (4G) only network it is necessary to configure the device to send SMS using the packet switched network as the circuit switched networks will no longer be available to use.

SIM Configuration

To support VoLTE and packet switched SMS it is necessary to use a SIM card on a network provider that supports the IMS service. Your SIM card provider offers IMS services in similar to the existing SMS, circuit switched voice, circuit switched SMS and packet switched GPRS data services. Most SIMs come pre-configured allowing analogue voice SMS and GPRS, but you can switch these services on and off as required. IMS is usually enabled as a service with large global suppliers and is switched on by default with providers who offer the service.

You will need to change to a SIM from a network provider that offers this service if you are currently unable to use the IMS service from your existing supplier.

The following table shows the typical services available for a SIM card from most large global suppliers and what services are generally turned on by default.

Circuit Switched Voice and SMS Sunset

As GSM (2G) and UMTS (3G) become less used around the world they will become increasingly obsolete and as such there will be more systems which will not be able to rely entirely on the GSM (2G) and UMTS (3G) networks. There have already been several SIM providers. who have announced sunset on the UMTS (3G) networks around the world which only leaves GSM (2G) to support circuit switched voice and SMS services in the short term where 3G is no longer available. Over time GSM (2G) will also be turned off and there will be no legacy networks available to support circuit switched network operation.

A few of the larger global network providers have committed to supporting GSM (2G) until late 2025 but none have committed past this date at the currently. GSM (2G) and UMTS (3G) have been superseded by LTE (4G) and most internet capable devices have already been moved over to the LTE (4G) network. However, in many existing installations there is a pressing requirement for LTE (4G) due to the increased voice and SMS capacity offered by the LTE (4G) network. As a result of this developers and customers will be required to make changes to their applications to facilitate the move over to an entirely LTE (4G) only network infrastructure.

Industrial ZETA Modem IMS Support

The Siretta ZETA family of LTE enabled industrial modems is shown below:

Circuit Switched Voice Migration to VoLTE

When using analogue voice and SMS services to communicate with remote parties, equipment and devices, the process to connect local devices to remote systems is shown below.

Voice Procedure:

1. Local unit dials remote party
2. Remote unit answers incoming call
3. Conversation takes place
4. Either local or remote unit can terminate the call

SMS Procedure:

1. Local unit sends message to remote party
2. Remote unit receives incoming message
3. Either party can initiate sending a message to the other

When using VoLTE or packet switched SMS the initiation procedure is identical but there are a few configuration requirements for either process which must be met first.

1. The SIM and network provider must support IMS
2. The device hardware must support IMS
3. The device must be configured to allow IMS services

Once these parameters have been met, the standard voice dial command or SMS send commands can be used to establish a voice call or send an SMS message over the IMS network using the VoLTE and packet-based SMS services.

Command Syntax

IMS should be set correctly in the APN which can be checked with the following:

IMS PDP profile should be set correctly and can be checked with the following:

IMS profile should be enabled which can be checked with the following:

For the ZETA-xxP family of modems IMS is shown as active in profile 2 (which is shown in row 2).

IMS registration state should be enabled which can be checked with the following:

Voice Procedure:

For voice calling, similar to a non-VoLTE call, the standard dial command can be used to establish a VoLTE call with the receiving party once the IMS settings have been established.

ATD

SMS Procedure:

To configure the device to send circuit or packet switched SMS the following settings can be used:

To send circuit switched SMS.

To send packet switched SMS.

For packet switched SMS sending, similar to circuit switched SMS, the standard command can be used to send an SMS to the receiving party once the IMS settings have been established.

Overall System Advantages

Once your system is setup to use IP traffic to initiate VoLTE calls and packet switched SMS messages instead of circuit switched voice and SMS there will be an immediate benefit in the overall operation of the system. This is because using IMS as the method of communication offers several advantages over circuit switched networks. Some of these key points are described below:

Additional Reading

The post Circuit Switched vs Packet-Switched Networks appeared first on Siretta Limited.

Demonstration of Solution

Resources used for this application note are as follows:
• ZETA-NEP-LTE4 (EU) modem (Low Power Modem with RS232 and USB serial): https://www.siretta.com/products/industrial-modems/lte-cat-4-mobile-network/enhanced-lte-cat-4-european-modem-with-gpio/
• Modem Starter Kit Quick Start Guide: ZETA-xxP Quick Start Guide
• Initial Modem Setup Guide Application Note: Initial Modem Setup Guide App Note – LP (siretta.com)
• Data enabled SIM card.
• A PC with an installed ‘Terminal Emulator’ program: Window 11 Laptop installed with Tera Term used for the purpose of this guide.
• AT command reference manual: ZETA-xxP-LTE1 / ZETA-xxP-LTE4 AT Command – https://pages.services/pages.siretta.com/zeta-xxp-lte1-zeta-xxp-lte4-at-command-reference-manual/?ts=1658149511127

Setup GPRS Connection Parameters

1. Set extended error messages by using at command below.

2. Set GPRS APN Name by using at command below.

Outgoing Connection (Old Commands – No longer supported).

3. If the sim card requires username and password use below at commands otherwise continue with step 4.

4. Open GPRS context 1 by using below command.

Note: This will return your ISP assigned IP address as seen below.

5. Open Socket on Port Number at IP Address (Or URL) using below at command.

6. If successful, this will return CONNECT.
7. Set protocol using below command.

Outgoing Connection (New Commands)

Note: Please note that this script and service provided by Siretta is for test purposes only. Siretta will not guarantee that this service will remain in operation indefinitely into the future. For applications which rely on using this service it is recommended that you maintain and run the script on your own server using the example script provided below.

Example PHP Script

Additional Reading

The post Request Time from the Network using GPRS appeared first on Siretta Limited.