Unable to send AT Commands to Arduino Uno

I am attempting to send SMS using an Arduino Uno attached to a GPRS Shield v2.0 (Board model SLD0198P) with a SIM900 chip on Com 3. The comport is setup at 9600 baud. The board signals the 3 seconds interval showing it is connected. I have two problems. (1) The serial monitor displays SMS Message Sender, but never displays ready and I am unable to send any type of AT commands. I send them but do not receive any response in the serial monitor. (2) When I click Tools Serial Port, I only see the Com ports, my GPRS Shield board does not appear. I am able to upload sketch to the board without any problems. Any help is greatly appreciated. I also attempted connection with Putty but no response either. Thank you

You mean the SeeedStudio SLD01098P , not SLD0198P

How are the Serial Port Select jumpers set?

http://www.seeedstudio.com/wiki/GPRS_Shield_V2.0 "3. Communication port configuration The GPRS shield can be controlled via hardware serial port or software serial port of Arduino. Here we use the software serial port as default. Choose it by inserting jumper caps as below."

Are you running the Serial Relay sketch shown on that same Wiki page?

My Serial Port Jumpers are set as shown in the link you provided. Just for testing I changed them which did not make any impact. Either way I do not see anything in the Serial Port monitor except SMS Messages Sender. Thank you

DelComm: (1) The serial monitor displays SMS Message Sender, but never displays ready and I am unable to send any type of AT commands.

What sketch are you running? I don't see any sketch on that wiki page that displays the text "SMS Message Sender".

Take a look at the web page in my signature. it deals with connecting and configuring SIM900 based modem.

Thanks for the follow up but still nothing returned from the Serial Monitor. Below are the steps I followed while reading the site you suggest.

  1. Connected External Power Supply
  2. Uploaded the sketch provided on the site - no problems
  3. Started Serial Monitor (at 19200 baud)
  4. Waited for the three second delay for the egreen network led (note - at this point nothing is displayed on the serial monitor)
  5. Made sure the Serial Monitor is set to 19200 baud and New Line
  6. Typed the command AT, clicked Send -- Nothing is returned on the serial monitor -- No errors reported anywhere

I am sure I am missing something pretty basic I just can't seem to find it.

If you loaded SerialRelay and followed the instructions then my conclusion would be that the modem is defective. You have confirmed that the jumpers are in the correct position for SoftwareSerial and that is the only part where an error can creep in.

The modem should respond to an AT command even if it cannot connect to the network.

In my continued effort to attempt to get this to work, I exchanged my GPRS Shield thinking you were on to something but still no change. I see SMS Messages Sender in the Serial Monitor but nothing else ever. I send basic commands, example AT and no response. I also never receive a Ready message. Any help would be greatly appreciated. I will keep trying. Note - Tools Board - Arduino Uno. Tools Serial Port show Com 1 or Com 3, it never shows the board name.

Any help would be greatly appreciated. Thank you

The library supplied with the IDE is intended for use with the official Arduino GPRS shield which uses a Quectel M10 chip rather than a SIM900.

I am assuming that the Uno is fully functional? You can connect LEDs to the pins used to communicate with the shield and get them to blink?