read data in text file on arduino

you are going to have to devise a protocol.

that is what a message will contain.

Read my blog posts of protocol design.. there are 4 post that will be helpful.

http://www.element14.com/community/people/phoenixcomm/blog/2013/02/15/nexgen-rss-continued-the-protocols

parts 1, 2, & 3

and

http://www.element14.com/community/people/phoenixcomm/blog/2012/12/29/flight-simulator-101-or-back-to-college-part-v--protocols parts 1 & 2

and why do you want to use ftp??? how far away are the two devices? FTP means that you are going to use the Ethernet shield

you can do it easier if you just use serial communication ala RS232 with level shifters.. or virtual Com port over USB..(painless)

thanks for the reply but designing a protocol is not in my capablities. althought i have a alternative idea.

I am using seeed wifi shield with arduino uno.

i want to read data from a webserver to change status of digital pin of arduino board.

for eg. i have connected a LED to my arduino board and connected the seeed wifi shield, so i want to be able to turn on and turn off the LED from internet using a web site.

how does the wifi shield receive data from web server???

please guide

P.S. seeed wifi shield based on RN-171

regards

Anand Vartak

it says in the datasheet of RN 171 that it supports HTTP client to send and recive data from a web server but there is no information about how to get data from the web server. The datasheet only describes posting data on web server.

please help.

Its on page 75 of their reference guide (google wifly user manual, first hit).

actually i had been through that datasheet but i could not understand how things are happening. i dont know much HTML. can u tell me how the web server makes connection to the module? do i have to first connect the web server as client and then keep the port open for the web server to communicate back.

can u explain the process to me

Hi Anand,

The server listens, it will respond to requests from the client RN-171. You pass the information you desire in the server response.

If you don't know when the server has information to supply, then you can periodically poll the server with requests from the client. This is not always an appropriate method but it's the easiest and most likely to work for you with the built-in functionality in your device. If you want to learn this in detail, look for http via google.

hi shabaz,

given my hardware configuration what is the best method for turning on an LED from internet.

you said the server listens and sends response, is it possible to send a user defined response

Hi Anand,

Check these examples for webclient on arduino.

http://arduino.cc/en/Tutorial/WiFiWebClient  ( single request )

http://arduino.cc/en/Tutorial/WiFiWebClientRepeating  ( poll method )

for this project to succeed you need to learn atleast basics of how a webserver/browser communicate.

mostly you will need the commands GET and host: and the server response

https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol

After getting a document on the server you wil need to cut some lines from the input to get to the values, even if the webserver hosts only a simple txt file.

hope this helps

It's a server, it will serve up anything you wish but the format will (should) be a valid formatted response. It's basic http. Hint: read up on HTTP GET method and 200 OK. The response from the server you can search using your arduino for any appropriate text - just depends on how good you are at parsing the response. Given limited RAM, Arduino's are not really geared for this but people do manage to get by - and your RN-171 may store the packet (I don't know). As mentioned earlier, you'd need to periodically poll to query the server.

i have been in contact with the seeedstudio tech support guys and even they dont have anything to say about the http connection. i am successful in creating a tcp socket in java. now trying to integrate it with my web server. my friend is helping me with it.

can anyone suggest a better hardware for wifi. the arduino wifi shield is a great option i guess but its too costly

i have been in contact with the seeedstudio tech support guys and even they dont have anything to say about the http connection. i am successful in creating a tcp socket in java. now trying to integrate it with my web server. my friend is helping me with it.

can anyone suggest a better hardware for wifi. the arduino wifi shield is a great option i guess but its too costly