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EHS6 Modem: TCP PAD Configuration Fails - PDP Context Problem | Thales IoT Developer Community

April 14, 2017 - 7:58pm, 4729 views

Dear Group:

What I am trying to do is configure the Gemalto EHS6 wireless modem as a
TCP PAD and Internet client, such that only TCP payload data flows across the
modem serial port once a TCP connection is established. So far I have failed.
A description of the modem configuration and AT commands used follows.  (i.e.
Please note that configuration is being done with Hyperterminal on a PC and that
the modem is connected to the PC via its serial port.)

The problem appears to be related to PDP context configuration. Please
advise me of the correct way to configure the modem as a TCP PAD.

I have confirmed that the modem has UMTS network connectivity and the SIM
being used is functional. In addition, the modem is able to receive SMS messages
via the network, and perform basic PDP context operations. The APN used to verify
that is telargo.t-mobile.com and the following AT command was used to configure
the PDP context and APN.

    AT+CGDCONT=1,"IP","telargo.t-mobile.com",,0,0

Also, I verified that the Internet server is functional and does not require
authentication.

The AT commands I am using to configure the modem as a TCP PAD and a description of
their use follows.

* Reset the modem to factory settings.

    AT&F

* Configure operation on a UMTS network with a GPRS core and the APN.

    AT^SICS=0,conType,GPRS0
    AT^SICS=0,apn,telargo.t-mobile.com

* Configure transparent service for a UMTS network with UTRAN RAN.
 (i.e. Service profile 2.) Note, that substituting "Socket" for "Transparent"
 as in the tutorial makes no difference, and I believe that Transparent is
 correct. Please advise me if this is wrong.

    AT^SISS=2,srvType,"Transparent"
    AT^SISS=2,conID,0

* Configure the Internet server address and Port and set 26=Ctrl-Z as the
  escape character. I have hard coded the IP address because the modem
  doesn't appear to have DNS resolution capability. Is there a way to
  configure the modem to perform DNS resolution.

    AT^SISS=2,address,"socktcp://10.224.141.12:634;etx=26;timer=300"

* Open Transparent Service. Initially the response is OK but if you
  wait for a short period the response is ^SIS: 2,0,94, "PDP: connection failed".
  If the command is successful, a TCP connection with the Internet server should
  be established at this point.


    AT^SISO=2

* Enable Transparent Service. This always fails. If the command is successful,
  it should be possible to send and receive TCP payload data via the modem
  serial port at this point.

    AT^SIST=2