• At Commands For Modem Testing

Hi, I have problems getting the SIM900 shield to operate.I have checked that the SIM is without PIN code, and I have checked that it works by using it in my mobile phone. The SIM is a prepaid card from Telenor in Norway.

I power the SIM900 from a separate 60W power supplyTrying to get the card to connect to the network, eveything is as described after pressing power on.However, it looks like the cards stops when it connects to the network. The NetLight turns off and does not blink anymore. I then have to remove power and start over for the power key to work again.-any idea what might be the problem?-should the AT commands work before I press the power key and get it connected?. Hi Tor.When the card connects to the network, the NetLight LED should be blinking every three seconds (that indicates it is properly connected to the network).To power up the shield you should press the power key for about 2 seconds. Then, the Status LED will light up and the NetLight LED will blink every 800 ms until it finds the network. When it finds the network, the NetLight LED will start blinking every three seconds.If it is not connecting to the network, it may be a problem with your card, or with your GSM shield.The GSM shield should be connected to the network before sending the AT commands.I hope this helps.Regards,Sara 🙂. Hi, i recently got a Sim900 module, i understand all the AT commands, and functions, ( this guide also helped me ) But i got a problem, the first step!

My net light only blinks once per second, and it stays that way for long time which means it cant acquire network, i dont know why?My module is connected to a 9v 1a power supply,The Sim card is in correct position.Ive read that sometimes, the Ant pin is not soldered properly, or also if the Manufacturer its from china, it wont with america signals.Do you know what could be happening?. Look for an AT-command-list like –SIM900AT.pdf– and find out more about signal quality, connections etc.You can start by checking the signal quality with a command like — SIM900.println(“AT+CSQ”) — (and feed the output back the serial port). Also check the commands AT+COPS? In different variationsThis will tell you if your antenna is working (CSQ) and if there are carriers you can connect to or are connected to.You can find out a lot more about your board and connection with AT commands, even without (or before ) a network connection!And I admit, it’s still difficult to connect these boards but you will learn a lot more about your board by trying these commands 🙂.

At Commands For Modem Testing

Sara,This is really a splendid tutorial; I would not have made my project work if it were not for you. Thank you so much.

I was trying to make a PIR-triggered-SMS alarm. My shield which is identical to yours kind a works ONLY without the auto-on snippet(so, I deleted this from the code and unplugged the D9 wire); however, in some 20 minutes, the shield turns off by itself. My intention is to manually switch it ON and leave it ON for a longer period of time (days). Would you know how to?. Hi sir,I am facing a problem in sending a message using GSM AT commands forSerial.print(“AT+CMGS=””r”); here instead of my number I am using a variable which has a mobile number.So the command I used looks likeSerial.print(“AT+CMGS=”” + myNum + “””); orSerial.print(“AT+CMGS=””);Serial.print(myNum);Serial.print(“””);but the problem is the code gets compiled but I am not receiving any messages for that number stored in the variable ‘myNum’.I am using Arduino UNO board,Please help me to solve this problem. Thank you for this tutorial.

I got it working with SMS sending, and have some additional advice. You may not need an extra power supply, if you are close to a base station. Arduino takes just a small part of the current that your PC can deliver to USB port. The rest may be enough to the GSM shield. Just connect +5V from Arduino to +5V of the shield.

That is an easy trial, and it worked for me. When you have your code ready, you can replace PC with an USB power bank. If your code is waiting for something to happen, you should use sleep mode inside the waiting loop and put also the shield to sleep mode. You can get easily over one month waiting time.

Choose a GSM ModemGSM ModemsA GSM modem, 3G modem or SIM box is basically a GSM phone without keyboard, speaker, battery and display. The terms SIM box, GSM gateway or GSM router are mostly used for devices that route phone calls through the GSM network and the term GSM modem or 3G modem for devices specialized in wireless data transmission. However for GSM modem software they often are interchangeable.A GSM modem provides the SMS software with a secure gateway to the GSM network, with only two limitations. The amount of SMS message that can be sent and/or received is limited to 12-30 messages per minute, depending on the GSM modem and network, and it is not possible to send SMS messages with alternative numeric or alphanumeric sender id's. GSM modems with an Ethernet port. Wavecom Fastrack Supreme GSM modemPros. Very reliable.

No modem drivers necessary. Connector can be fixed securely to the serial port. Industrial design, usually very robust. External power supply. External antenna, suitable for server rooms. Designed for 24/7 operationCons.

Serial ports are often not available on new computersBrands and models. ConiuGo serial port modems. Cinterion MC55iT, MC52iT, TC65T. Siemens MC55iT, TC65T, TC45T, TC35i. Wavecom Fastrack Supreme/M1306B/M1206, MOD2.

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Sierra Wireless AirLink Fastrack Xtend. Multitech MTCBA-G-F4. Siemens tc35i GSM modemSerial GSM modem over TCP/IPA very reliable way to use a serial GSM modem on a server that has no serial port is with a TCP/IP to RS232 convertor. An extra advantage is that the actual GSM modems can be placed anywhere in the network, even on remote locations.

Diafaan SMS Server can use GSM modems over a TCP/IP connection directly, without the need for any additional COM port drivers.USB to RS232 converterAnother, slightly less reliable, way to use a serial GSM modem on a server that has no serial port is with a USB to RS232 converter. The USB to RS232 converter installs a virtual serial port on the PC that is used by Diafaan SMS Server. GSM modems with a USB port.