Telit http issue

Wireless & IoT
1

Hi guys,

using a Telit GM862-QUAD PY with selint=1 I try to connect to a server using:

at#SKTD=0,80,“www.sparkfun.com”,255

< CONNECT

(The 255 in the end should tell the modem that the connection will be kept until I send +++)

So, I try to do a GET request, e.g:

GET / HTTP/1.1

Host: http://www.sparkfun.com

And I get the expected response from the server, however when I try to do the next GET request, all I get is “NO CARRIER”

I’ve even tried to add

Connection: keep-alive

to the GET requests (even though they should not be needed with HTTP/1.1).

Can anybody explain how I can get a GM862 HTTP session to last longer than one command?

Kind regards,

Michael Thomsen

2

First of all, The remote update software includes both Python (unit side) and PHP (server side) components allowing updating of Telit modules in the field. It utilises HTTP meaning a simpler deployment (FTP server is not required). It supports a range of features including multiple software types, multiple versions, and authentication.

3

Each time you open a socket, you have to define the specific socket parameters (server ip, port number, etc). Once you have opened the socket, in my experience, you can only send one http request/socket. Once you receive the response to your request, and receive NO CARRIER, you will be able to open a new socket (after setting any parameters you need to change), and send another request.

4

I’d try accessing the sparkfun.com site using a browser with Wireshark/Ethereal and see what’s in their GET request. also try another site, as it may kick off unknown browsers.

I am also using the GM862 for .NET Micro Framework as we speak, SMS complete, HTTP Complete, now working on FTP (www.earthed.net.au)

C#:

sCmd = “AT#SKTD=0,”+iPort.ToString()+“,"” + sDomain + “",0,0\r”;

possible responses: {CONNECT,NO CARRIER,+CME RRROR}

sHTTP_METHOD = “GET”;

sUriEncoded = HttpUtility.UriEncode(sUri); <<<<<<<< This caught me out (e.g. " " ->“%20”)

sCmd = sHTTP_METHOD + " " + sMvcMethod + sUriEncoded + " " + sVersion + “\r\n”;

sCmd = "Host: " + sHost + “\r\n”;

sCmd = “Connection: keep-alive\r\n”;

sCmd = “\r\n”;

5

A Socket is an End-Point of To and From (Bidirectional) communication link between two programs running on the same network . basics of socket … http://csharp.net-informations.com/comm … amming.htm Once you receive the response to your request, and receive NO CARRIER, you will be able to open a new socket and send another request.

Bikitha.