Hello,
I am working with a EC200A module using TCP socket communication via AT commands.
Firmware version: EC200AAUHAR01A14M16_01.200.01.200
This issue has been observed on two different units, deployed in different countries: Mexico & Chile
Additionally, this product has already been deployed in more than 600 units in the field, which makes this behavior especially relevant from a reliability and scalability standpoint.
The module is able to:
- register to the cellular network correctly
- activate PDP context
- resolve DNS successfully
- open a TCP socket
- send data (
SEND OK)
However, after sending data, the TCP socket is automatically closed, and the module reports: +QIURC: “closed”,0
Configuration and steps
AT
ATE0
AT+QIACT=1
AT+QIOPEN=1,0,“TCP”,“example.com”,80,0,0
// Response:
+QIOPEN: 0,0
AT+QISEND=0
Module response: >
// Payload sent + Ctrl+Z (0x1A)
SEND OK
+QIURC: “closed”,0
From a general TCP perspective, under what conditions does EC200A generate +QIURC: "closed" and how should this event be handled at application level?
Best regards!
Dear @AnthonyRFC ,
Thank You for Reaching out to us,
- From a general TCP perspective, under what conditions does EC200A generate
+QIURC: "closed" and how should this event be handled at application level?
On the Quectel EC200A module, the Unsolicited Result Code (URC) +QIURC: “closed”, is generated when a TCP socket service is terminated by either the remote peer (the server) or due to a network error.
You may try to re-open the connection using AT+QIOPEN.
If AT+QIOPEN fails continuously (e.g., 5 times), deactivate and re-activate the PDP context before trying again.Connection Maintenance: For high-reliability field deployments, it is recommended to periodically send small “heartbeat” packets to detect if a connection has become silent or abnormal before a critical data transmission is attempted.
Thank You and Have a Great Day!
Dear @Alvin295337 ,
Thank you for the clarification.
We understand that +QIURC: "closed" is expected when the socket is terminated by the remote peer or due to a network issue. The application logic already handles reconnections and PDP reactivation as recommended.
However, we are facing a practical challenge:
The SIM provider is attributing the issue to the EC200A module, despite the fact that the same hardware and firmware works correctly with a different SIM card (TCP and TLS connections open and data is received normally).
From a troubleshooting perspective, we need a way to provide objective technical evidence to the SIM provider that the issue is network-related rather than module-related.
Question
Are there any recommended diagnostic methods or logs from the EC200A (e.g., specific AT commands, TCP/SSL debug outputs, or network status indicators) that can help distinguish between:
- Server-initiated closure
- Network/APN-level filtering or firewalling
- Module-side TCP/IP stack issues
This would help us provide concrete proof to the SIM provider and resolve the dispute.
Thank you for your support.