1. Information Elements related to TCP/IP
| Information | Description |
| +CIPEVENT: NETWORK CLOSED UNEXPECTEDLY |
Network is closed for network error (Out of service, etc). When this event happens, user’s application needs to check and close all opened sockets, and then uses AT+NETCLOSE to release the network library if “AT+NETOPEN?” shows the network library is still opened. |
| +IPCLOSE: <client_index>, <close_reason> |
Socket is closed passively. <client_index> is the link number. <close_reason>: 0 Closed by local, active 1 Closed by remote, passive 2 Closed for sending timeout |
| +CLIENT: < link_num>,<server_index>,<client_IP>:<port> |
While TCP server accepted a new socket client, the index is <link_num>. The TCP server index is <server_index>. The peer IP address is <client_IP>. The peer port is <port>. |
2. Description of <err_info>
The fourth parameter <errMode> of AT+CIPCCFG is used to determine how <err_info> is displayed.
If <errMode> is set to 0, the <err_info> is displayed with numeric value.
If <errMode>is set to 1, the <err_info> is displayed with string value.
The default is displayed with string value.
| Numeric Value | String Value |
| 21 | Operation failed |
| 0 | Connection time out |
| 1 | Bind port failed |
| 2 | Port overflow |
| 3 | Create socket failed |
| 4 | Network is already opened |
| 5 | Network is already closed |
| 6 | No clients connected |
| 7 | No active client |
| 8 | Network not opened |
| 9 | Client index overflow |
| 10 | Connection is already created |
| 11 | Connection is not created |
| 12 | Invalid parameter |
| 13 | Operation not supported |
| 14 | DNS query failed |
| 15 | TCP busy |
| 16 | Netclose failed for socket opened |
| 17 | Sending time out |
| 18 | Sending failure for network error |
| 19 | Open failure for network error |
| 20 | Server is already listening |
| 21 | No Data |
| 22 | Port Overflow |
3. Description of <err>
| <err> | Description of <error> |
| 0 | Operation succeeded |
| 1 | Network failure |
| 2 | Network not opened |
| 3 | Wrong parameter |
| 4 | Operation not supported |
| 5 | Failed to create socket |
| 6 | Failed to bind socket |
| 7 | TCP server is already listening |
| 8 | Busy |
| 9 | Sockets opened |
| 10 | Timeout |
| 11 | DNS parse failed for AT+CIPOPEN |
| 12 | Unknown error |
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