Invalid or no response from the device

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This topic contains 25 replies, has 2 voices, and was last updated by  Mojako 8 years ago.

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  • #5092 Reply


    The IMEI is read from the module, so I dont think the SIM card would matter for that.
    Did you have the software serial selected(jumpers) as shown in the image?(see link)

    • This reply was modified 8 years, 1 month ago by  Admin.
    #5104 Reply


    My jumpers were not like the ones in the picture. I thought the shield came by default in software serial. I changed my jumpers and still have the same errors with modem test and AT command tester

    Starting modem test…ERROR, no modem answer.
    Checking IMEI…Error: Could not get IMEI

    #5106 Reply


    What arduino board are you using?

    #5107 Reply


    arduino uno

    #5108 Reply


    R3, the most recent one.

    #5109 Reply


    What is the status of LEDs – Power-on indicator, Status indicator and Net indicator?

    LED Status Function
    Power-on indicator(Green) Off Power of GPRS Shield is off
    On Power of GPRS Shield is on
    Status Indicator(Red) Off Power off
    On Power on
    Net indicator(Green) Off SIM900 is not working
    64ms On/800ms Off SIM900 does not find the network
    64ms On/3000ms Off SIM900 finds the network
    64ms On/300ms Off GPRS communication

    #5110 Reply


    I have the Power LED(green) on
    I have the Status Indicator(red) on
    I have the Net Indicator(green) blinking at every 300 ms

    #5112 Reply


    its actually more like every 800ms

    #5113 Reply


    I think the software serial should be the one on the left.
    On the wiki page, the location of the jumpers change after the boards are stacked…
    So far what I’ve done is loaded this code onto my arduino (without gprs)

    #include <SoftwareSerial.h>

    SoftwareSerial mySerial = SoftwareSerial(2,3);

    void setup()


    void loop()
    if (mySerial.available())
    if (Serial.available())


    Then i connect my gprs and attempt to use your AT Tester and it gives me the above mentioned errors. Is there anything im missing? is there a reason why we’re using pins 2 & 3 for tx and rx? shouldnt we be using
    D7: Used as RX of software serial port
    D8: Used as TX of software serial port

    #5114 Reply


    The baud rates should match..

    Serial.begin(19200); h/w serial port
    mySerial.begin(19200); s/w serial port

    The SIM900 module should be configured for the same baud and you should choose teh same rate in the AT Command Tester as well…

    If SIM900 is not configured for above baud rate, then you should try different rate in the in the shield and reload..

    #5993 Reply


    My Problem same like Jerry, I use Adruino Mega 2560 and still can not use my GPRS Shiled V 2.0.
    My Jumper set to HardwareSerial and also upload TestModem Sketch. and still massage “ERROR, no Modem answer”. Do I missed something? please help

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