sim900a At command problem

[deebakece]

Hi

I have prolific usb to serial connecter which is used to connect pc and sim900a... when i connect it displays +cpin ready cfun 1 call ready that means that sim card working properly.. but what ever the AT commands i type its not getting any response from Sim900a.. so to check whether usb to serial connector is working properly what i did i shorted Rx and Tx line and checked with hyperterminal and rsterminal.... what ever i type in keyboard its getting printed back so the cable is working fine.. what may be the problem am stucking here.. its not responding for any commands how could i try or its again cable problem.. Pls suggest me..


Thanks in advance..!

 

[DineshSL]

Hi,

How you get it displayed +cpin ready ?
Check voltages used in prolific module and sim900a module for Tx,Rx lines. Both should be same; TTL or standard-RS232 voltages.

 

[deebakece]

When i am connecting power supply to module its getting printed cpin1..

 

[DineshSL]

Hi,

..it's getting printed cpin1 on where ?

Like mentioned earlier Check voltages used in prolific module and sim900a module for Tx,Rx lines. Both should be same; TTL or standard-RS232 voltages.

If your modules have CTS and RTC lines, connect them together. Search the web on "null-modem configuration"; that is how your modules should be wired.

Hope this helps you.