[SOLVED] Interfacing SIM 300 with serial port to hyper terminal

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Hello,

I wanted to interface SIM 300 (Ver 7.03) modem having RS 232 interface with PC using serial port. I made a male-female DB9 connector by connecting pin 2,3 & 5 such that pins 2 and 3 were exchanged at one end. Then, connected the device to PC, inserted sim card, connected the adaptor to SIM 300 and opened hyper terminal. I used the settings as in the post below :

https://www.edaboard.com/threads/197380/

Then typed AT in the screen. There was no display on the hyper terminal screen (neither of AT or any acknowledgement).

I tried this for both COM1 and COM2.

Pls. tell me if I am doing something wrong.


Thanks,
Y Li
 

Some basic troubleshooting to start...

1) Disconnect the cable from your modem and short pins 2 & 3. Is Hyperterminal showing what you typed? No...Wrong COM port selected or Bad Cable?

2) Are you sure the modem you have requires pins 2 & 3 to be reversed? Try a straight-through connector?

3) Are you sending a return after the command?
 


Thanks for replying. I changed the emulation mode to tty and things started working. BTW just needed one info. Every-time, when I power up the modem, do I have to use AT+CREG=0 for the SIM registration. Need to know it as I will have to finally interface it with a uC.

Thanks & regards,
Y. Li
 
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"AT+CREG=0" disables unsolicited result codes - it doesn't affect network registration. If you need to disable those codes, you'll need to send that command.
 
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    Y.li

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So does it mean that I dont have to register to the n/w every time GSM modem is powered on ? Also, if I dont disable the codes (AT+CREG=0), does it affect the functioning of GSM modem in general. I need to send alert messages once a while.

Thanks,

Y. Li
 

The module will register itself on the network when you power it up - the "AT+CREG" command doesn't affect that. Sending "AT+CREG=0" only tells the module not to send unsolicited commands. If you send "AT+CREG=1" or "AT+CREG=2" the module will send a message whenever the network registration changes. For example, if your device is moving and the cell tower it is connected to changes it would send a "+CREG" message. Or if the module loses connection to the cell tower it would send a "+CREG" message. If you send the command "AT+CREG=0" it will not send these messages.
 
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OK, thanks.

Y Li
 

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