SIM300D interfacing with hyperTerminal - NO DISPLAY

[soulhacr]

Hi i am trying to connect sim300d with hyperterminal via serial port but when i open my hyperterminal i cannot write anything. it just gets stuck for some time and nothing is displayed. i think my module is fine as the network status led is working fine but i cannot send any command to the module. i have connected my sim300d with my serial port using max232 . i have only used pins 2,3,5 of max232. i am running my max232 on 5 Volts and my sim300d on 4.1 Volts .

Are there any other pins i need to connect?

• My baudrate is set to 9600 (hyperterminal).
• By default sim300d is set at autobauding.
• i have only one com port so i knw that i am connecting to the right port. and i have also checked my port and it is working fine.

please suggest some sort of solution. i really need some help.

 

[ckshivaram]

you cant predict your modem is fine just by the blinking of LED's.

first do a loop back test to confirm if the serial port of your PC is working or not.. connect serial cable and short pin 2 and 3 and keep typing some characters from keyboard... it should be visible on the window.....

if it does not come then short the pins 2 and 3 on the connector of the PC and type to see if you get the characters on the window when you type.. if you get it then you interface the modem to PC and tell what happens......

 

[soulhacr]

you cant predict your modem is fine just by the blinking of LED's.

first do a loop back test to confirm if the serial port of your PC is working or not.. connect serial cable and short pin 2 and 3 and keep typing some characters from keyboard... it should be visible on the window.....

if it does not come then short the pins 2 and 3 on the connector of the PC and type to see if you get the characters on the window when you type.. if you get it then you interface the modem to PC and tell what happens......

Thanks for replying ckshivaram

I have done the loop back test. First I connected pins 2 and 3 and nothing displayed on hyper terminal. I don't know why but nothing was displayed and hyper terminal got stuck when I typed any characters. Then I searched on Google and found that for RS232 I should have three short circuits for loop back test. These short circuits were:

1. Connection of pin 2 and 3
2. Connection of pin 4 and 6
3. Connection of pin 7 and 8
4. Leaving pins 1, 5 and 9 alone

Then I made these three short circuits. With these short circuits, I was able to see typed characters displaying in the hyper terminal. That's why I said in my previous post that serial port is working.

Please help me.

 

[ckshivaram]

but shorting 4 &6 7 & 8 are not at all required.. Just shorting pins 2 & 3 should give you loop back result as you are going to use NULL modem.. so there is no question of any other pins other than pins 2,3,5.

You should get the output of loopback only with shorting pin 2 & 3.

if you get the output then your modem will also work ...
connect modem and test again.. if the output does not come then change the tx and rx pin connection at one end of cable and try...

but your loop back test is not working if you try to short other pins other than pin 2,& 3.

 

[soulhacr]

but shorting 4 &6 7 & 8 are not at all required.. Just shorting pins 2 & 3 should give you loop back result as you are going to use NULL modem.. so there is no question of any other pins other than pins 2,3,5.

You should get the output of loopback only with shorting pin 2 & 3.

if you get the output then your modem will also work ...
connect modem and test again.. if the output does not come then change the tx and rx pin connection at one end of cable and try...

but your loop back test is not working if you try to short other pins other than pin 2,& 3.

ckshivaram I have checked another serial port but it is working too by merely connecting pins 2 and 3. I have used this serial port around 1 month ago to burn my micro controller so I know it works.

ckshivaram Is there any other way to check the serial port?

 

[ckshivaram]

try to follow my earlier post of connecting modem and tell what happened.........

 

[soulhacr]

try to follow my earlier post of connecting modem and tell what happened.........

This is very strange ckshivaram. By connecting only pins 2 and 3, I am unable to see any result on hyper terminal. But I have downloaded a software **broken link removed** to test my serial port. I connected only pins 2 and 3 and It worked fine. So it means my serial port is working. Is there any chance that my hyper terminal is corrupted?? As with pins two and 3 connected, I could not see any result being displayed on my hyper terminal. (But when I tested my serial port with 3 short circuits as I mentioned in previous post, it was displaying what I was entering).

Thanks.

 

[ckshivaram]

yes can remove and reinstall hyperterminal software or use hyperterminal look alike softwares for testing...

Hyperterminal is sensitive to virus... hope you have clean system.

 

[soulhacr]

This is the circuit i have made.
i have reinstalled my hyperterminal and still no change. please check my circuit to see whether it is correct or not.

 

[anayyer]

ckshivaram did you see the circuit? Is there something wrong with it or every thing is fine?

 

[soulhacr]

ckshivaram please help me out over here. i really need to get this project working.
thanks