User guide

Redpine Signals, Inc. Proprietary and Confidential.  Page 49 
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0x4F 0x4B 0x01 0x0D 0x0A 
3.4.7  Query a Listening Socket’s Active Connection Status 
Description 
This command retrieves handles of active socket connections established 
through the listening socket. This command can be issued when a 
listening/server TCP socket has been opened in the module, to get information 
about the remote peer’s client socket. 
Command 
at+rsi_ctcp 
Usage 
at+rsi_ctcp=hn\r\n 
Parameters 
hn – TCP listening socket handle for an already open listening socket in the 
module. 
Response 
Result Code 
Description 
OK<hn><IP_Address><Port> 
An active socket handle. <hn> is 
returned as two‟s complement.  
hn >=0: A handle to an active 
connected socket. Returned as 
hex. For example, if hn = 7, it is 
returned as 0x07 
hn =-1: No connection has been 
established yet between module‟s 
listening socket and remote peer. 
Returned as two‟s complement 
(0xFF). 
IP_Address is the client/remote 
peer‟s IP address. Returned in 
hex, 4 bytes. 
Port is the port number on which 
the client/peer is exchanging 
data. Returned in hex, 2 bytes 
. For example, if the port number 
is 8001 (0x1F41), then first 0x41 










