modem ELS61T-E2 problem using the TCP telnet interface to execute AT commands | Telit Cinterion IoT Developer Community
November 18, 2018 - 6:28pm, 2733 views
HI all,
I have a modem ELS61T-E2 and I’m 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
Hello,
The default IP for the terminal (also for AT commands via telnet) is 192.168.1.1 so I suppose that you have reconfigured it to 192.168.0.3.
Have you made any changes in OpenWrt Linux configuration?
As for RS232 ASC0 interface available via 9-Pole D-sub connector it should be working in any configuration regardless of the firmware version. You should be using RTC/CTS hardware flow control. The default port setting is 115200 8N1. Each command you send ***** to be terminated with <CR> character.
Can you see any URC's on that terminal? Sending AT commands could not be possible if you have configured System.out for Java applications on this interface. If you will not succeed with ASC0 you could also try to login to Linux via Telnet or SSH and then connect to one of the module's USB interfaces from there. Please check then with AT^SCFG? command if there is System.out configured and where.
Regards,
Bartłomiej
Hi Bartlomiej
Thanks for your reply.
Yes, we reconfigure the ip on this file /etc/config/network according to the documentation and we didn't make any change on OpenWrt Linux configuration.
This modem was working as expected with AT commands via telnet until last Sunday.
Our rs232 terminal emulator is configured with the configurations that you indicate (115200 8N1 HFC) and we still not having access to the At interface. This terminal emulator is working well with other modems I’m assuming that the terminal emulator is ok.
I don't see any Unsolicited Result codes (URCs) apart from the system log where we have the error:
******.err ser2net[976]: Could not open device /dev/ttyACM2 for port 1234: No such file or directory.
We didn’t configure System.out for Java applications on any interface.
I have access via SSH as root to the modem but I don’t know how to connect to one of the module's USB to execute the AT^SCFG?
Thanks
Hello,
This error suggests that OpenWrt cannot access the module's USB port. That could be the reason why it resets the telnet connection on port 1234. Unfortunately I'm also not Linux expert. I think that you could try some standard Linux commands to debug if the system can see the module's USB interfaces. Probably no terminal emulator program is available to access serial ports in a convenient way but you could use cat command to read and echo to write to a serial interface. For example cat < /dev/ttyACM1 could be used to read.
If it turns out that the module is not enumerated and not accessible it could suggest some hardware problem with the module or terminal. You could then try to do module's firmware update. If this will not work you may need to contact your local Gemalto office or distributor.
Best regards,
Bartłomiej
Hi Bartlomiej
Can you send me the modules firmware update by email? Or is this firmware available for download?
Thanks
I have sent you an email.
Regards,
Bartłomiej
Hi Bartlomiej
Can you send me the modules firmware by email?
Thanks
Hi Milos,
Do you have any particular problems?
Can you paste ATI1 reply to identify the module type and firmware version?
Regards,
Bartłomiej