Hi, I have been having a number of issues trying to get FTP uploads/downloads to work from an FTP server using AT commands and a GSM/GPRS shield (SIM900) - i have a tried a lot of example code but nothing seems to work so i have decided to go back to squar 1 and explain what exacly i am doing and see if poeple think makes logical sence or whether my aproach is completely flawed.
As i understand it the FTP process requires two channels - one channel for data and the other channel for commands.
1) Attempt to open a TCP connection to the ftp server on port 80 with the correct APN, username and password using the relavant AT commands.
2) Once a connection is made attempt to open an FTP session on port 21 with the correct APN, username and password (same as above) using the relavent AT comands.
Does this seem like the right aproach or am i way off here.
I can get the first part to work and i can even send test data to the server although i have no idea where the data goes as there doesnt to be anywhere for it to go as i havent explicity told it to it where to go i just get a message back from the shield saying that the data has been sent.
The second part always fails due to a timeout error.
Initially i did it without setting up the TCP connection but then it seemed to me that this wouldnt work since there was no data connection.
Any help/guidance here would be much appeciated.