i Send AT commands from 8051 to a TMAS GSM modem , then i link up the Tx line to hyper termnial

That is called "Command Echo" and is perfectly normal.

You need to look in the modem's manual to find the AT command to disable echo...

That is called "Command Echo" and is perfectly normal.

You need to look in the modem's manual to find the AT command to disable echo...

hi,

the command error is turn off, just to check is i send a AT+CREG? it should reply something lik CREG=<mode>,1 how ever i only saw AT+CREG? in the hyperTerminal

i have check the RS232 interface with the osilloscope so the input and from the 8051 to rs232 to the modem is correct.

btw, the modem i am using is TMAS GSM modem model number tma-t35i.

been trying to troubleshoot for days.. but still cant find what when wrong. other then Tx Rx and Ground pin, is there another pin i need to connect?

"i Send AT commands from 8051 to a TMAS GSM modem , then i link up the Tx line to hyper termnial"

Not sure what you actually mean by that?

Is it like this:

MCU Tx Out ------------+------------> Modem Tx In
                       |
                       |
                       |
                       +------------> Hyperterminal

ie, you are using Hyperterminal to monitor what you're sending to the modem?

Or what?

If not, then please draw your setup - note that you need to use the 'pre' and '/pre' tags as described for posting source code: www.danlhenry.com/.../keil_code.png
See also: http://www.keil.com/forum/tips.asp

Remember: the "TX" pin on a modem (DCE) is an Input - it supplies the data to be transmitted.

See: http://www.keil.com/forum/docs/thread10745.asp

The modem's manual will tell you what other signal(s) it requires.

See: http://www.keil.com/forum/docs/thread15497.asp

thanks alot for your information, I actually make a mistake of Tx from the mcu to the Rx of the modem .

thanks alot, now i am able to continue the next part of my school project

hi, i have a new problem, when i receive a sms , is there a AT command just to show the message only, and not all the time date from who...

thank you

What does the AT command reference tell you?

Your question sound similar to: Is there a function that allows me to see the contents of a file, without first having to do a directory lookup to figure out if the file exists, and what its name is.

All of the AT commands available on your paticular module will be listed in its AT Commands Manual