Sim900 gsm module is not working at command

[enrique34]

HI EVERYBODY;

i am using SIM900 gsm module and connected RX(9),TX(10) pin with RS232 to PC..

i am receive "NORMAL POWER DOWN" when module is manual close...

but i am not receive "RDY" or "OK" when send to "AT" command,

all commands back to receive....

 

[ckshivaram]

do you activate the ignition key in the modem too.. did you connect max232 for modem....

 

[enrique34]

yes i am active to modem with POWERKEY and POWERKEY_OUT
netlight pin flash to led.
connect to max232
modem connect is true because i am receive "NORMAL POWER DOWN" when close to modem with POWERKEY and POWERKEY_OUT

VBAT 4.0V with LM2576-ADJ
SIMCARD not connected

 

[CADiLO]

>>>>connect to max232

CONNECT to max3232 3.0v only!!!

 

[enrique34]

Thanks...
i am not send ENTER ascii
module is return "OK" when send AT$0D )