Overview
This guide explains advanced IP connectivity functions for Siretta industrial modems, including TCP sockets, UDP sockets, SSL/TLS security, MQTT communication and HTTP/HTTPS requests.
| Part Number | Description |
|---|---|
| ZETA-GEP-LTE4 (EU) | Low Power LTE Cat 4 European Modem with GPIO and GNSS |
| ZETA-NEP-LTE4 (EU) | Low Power LTE Cat 4 European Modem with GPIO |
| ZETA-N-LTE (EU) | High Performance LTE Cat 4 Modem with GPIO |
| ZETA-NSP-LTE1 (EU) | Low Power LTE Cat 1 Modem |
| ZETA-NLP-LTE1 (EU) | Ultra Low Power LTE Cat 1 Modem |
| ZETA-G-GPRS | GSM/GPRS Modem with GNSS |
| ZETA-N2-GPRS | GSM/GPRS Modem |
This guide explains how to:
Expected Result
At the end of this guide the modem should be capable of secure IP communication and advanced network connectivity.
Before continuing:
| COM3 - Tera Term VT |
¶ File Edit Setup Control Window Help |
|
AT#SGACT? |
Expected Result
The modem should report an active packet data session with a valid IP address.
TCP sockets provide reliable connection-oriented communication between the modem and a remote server.
| COM3 - Tera Term VT |
¶ File Edit Setup Control Window Help |
|
AT#SD=1,0,80,"example.com",0,0,1 |
| Parameter | Description |
|---|---|
1 |
Socket identifier |
0 |
TCP mode |
80 |
Remote server port |
"example.com" |
Remote hostname |
| Parameter Position | Meaning |
|---|---|
| 1st parameter | Socket number |
| 2nd parameter | Protocol type |
| 3rd parameter | Destination port |
| 4th parameter | Remote address |
| 5th parameter | Closure timeout |
| 6th parameter | Connection timeout |
| 7th parameter | Connection mode |
Important Note
TCP communication guarantees packet delivery and correct packet ordering.
Once connected, the modem enters online data mode.
| COM3 - Tera Term VT |
¶ File Edit Setup Control Window Help |
|
CONNECT |
Data typed into the terminal is transmitted directly to the remote server.
Use the modem escape sequence:
+++
After exiting online mode, AT command mode becomes available again.
Important Note
A guard time is normally required before and after the
+++escape sequence.
| COM3 - Tera Term VT |
¶ File Edit Setup Control Window Help |
|
AT#SH=1 |
| Command | Description |
|---|---|
AT#SH=1 |
Closes socket 1 |
UDP provides lightweight connectionless communication suitable for telemetry and low-overhead applications.
| COM3 - Tera Term VT |
¶ File Edit Setup Control Window Help |
|
AT#SD=1,1,5000,"example.com",0,0,1 |
| Parameter | Description |
|---|---|
1 |
UDP protocol mode |
5000 |
Remote destination port |
Important Note
UDP communication does not guarantee packet delivery or delivery order.
SSL/TLS encryption secures communication between the modem and remote services.
| COM3 - Tera Term VT |
¶ File Edit Setup Control Window Help |
|
AT#SSLEN=1,1 |
| Command | Description |
|---|---|
AT#SSLEN |
Enables SSL/TLS functionality |
| Problem | Possible Cause |
|---|---|
| Certificate validation failure | Incorrect CA certificate |
| SSL handshake timeout | Unsupported TLS configuration |
| Connection rejected | Invalid server configuration |
| Secure socket failure | Firmware limitation |
Important Note
SSL/TLS support varies depending on modem firmware and modem series.
MQTT is widely used for industrial IoT telemetry and cloud communication.
| COM3 - Tera Term VT |
¶ File Edit Setup Control Window Help |
|
AT#MQCFG="broker.hivemq.com",1883 |
| MQTT Component | Description |
|---|---|
| Broker | MQTT server |
| Topic | MQTT message path |
| Publish | Sending MQTT data |
| Subscribe | Receiving MQTT data |
| COM3 - Tera Term VT |
¶ File Edit Setup Control Window Help |
|
AT#MQPUB="sensor/temp","25.4" |
Important Note
MQTT functionality varies depending on modem firmware capability.
HTTP and HTTPS allow communication with web servers and cloud APIs.
| COM3 - Tera Term VT |
¶ File Edit Setup Control Window Help |
|
AT#HTTPQRY=0,0,"http://example.com" |
| Command | Description |
|---|---|
AT#HTTPQRY |
Performs HTTP query |
| Problem | Possible Cause | Solution |
|---|---|---|
| Socket connection failure | Invalid APN or IP context | Verify packet data activation |
| DNS resolution failure | Network DNS issue | Use direct IP address |
| SSL connection rejected | Invalid certificate | Verify TLS configuration |
| MQTT broker unreachable | Firewall or routing issue | Verify server connectivity |
| HTTP timeout | Poor signal quality | Improve RF conditions |
| Step | Action |
|---|---|
| 1 | Verify active packet context |
| 2 | Open TCP or UDP sockets |
| 3 | Configure SSL/TLS |
| 4 | Configure MQTT communication |
| 5 | Configure HTTP/HTTPS |
| 6 | Verify remote connectivity |
Support
For further assistance, please contact the Siretta support team.