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modem ELS61T-E2 problem using the TCP telnet interface to execute AT commands | Thales IoT Developer Community

November 18, 2018 - 6:28pm, 2189 views

HI all,

I have a modem ELS61T-E2 and Im using the TCP telnet interface to execute the AT commands basically to send and receive SMSs and delivery reports.

 

This modem ELS61T-E2 was working fine, but now the modem is closing the tcp connection to port 1234 every time that we try to send a AT command.

 

The process ser2net is started and is using the configuration file /etc/s2n.conf  

 961 root       836 S    ser2net -c /etc/s2n.conf  

 

root@ELS61-E:/tmp/fw# cat /etc/s2n.conf

1234:telnet:0:/dev/ttyACM2:115200

 

The ser2net version is

root@ELS61-E:/tmp/fw# ser2net -v

ser2net version 2.10.0     

 

On TCP flow connection we can see the modem closing the connection [RST] after receiving the ATI command. The modem IP is 192.168.0.3.

 

Source                SRC Port Destination           DST Port Protocol Length Info

192.168.0.168         49961    192.168.0.3           1234     TCP      66     49961 → 1234 [SYN] Seq=0 Win=8192 Len=0 MSS=1460 WS=4 SACK_PERM=1

 

Source                SRC Port Destination           DST Port Protocol Length Info

192.168.0.3           1234     192.168.0.168         49961    TCP      66     1234 → 49961 [SYN, ACK] Seq=0 Ack=1 Win=29200 Len=0 MSS=1460 SACK_PERM=1 WS=8

 

Source                SRC Port Destination           DST Port Protocol Length Info

192.168.0.168         49961    192.168.0.3           1234     TCP      54     49961 → 1234 [ACK] Seq=1 Ack=1 Win=65700 Len=0

 

Source                SRC Port Destination           DST Port Protocol Length Info

192.168.0.3           1234     192.168.0.168         49961    TCP      60     1234 → 49961 [FIN, ACK] Seq=1 Ack=1 Win=29200 Len=0

 

Source                SRC Port Destination           DST Port Protocol Length Info

192.168.0.168         49961    192.168.0.3           1234     TCP      54     49961 → 1234 [ACK] Seq=1 Ack=2 Win=65700 Len=0

 

Source                SRC Port Destination           DST Port Protocol Length Info

192.168.0.168         49961    192.168.0.3           1234     TCP      59     49961 → 1234 [PSH, ACK] Seq=1 Ack=2 Win=65700 Len=5

 

0000  41                    ATI..

 

Source                SRC Port Destination           DST Port Protocol Length Info

192.168.0.3           1234     192.168.0.168         49961    TCP      60     1234 → 49961 [RST] Seq=2 Win=0 Len=0

 

This modem also has a rs232 interface and from this interface, we cannot also send any At command.

Probably we need a firmware update. Can you send me the latest firmware for this model ELS61T-E2?     

Thanks for your help