SIM900-Server not available to clients while still in listening mode

Hai,
I am using SIM 900 modem as a server. My Gprs server is running correctly and clients can connect to it. But after listening for a short time, it becomes unavailable in the network.i.e, no clients can connect to it. But when I checked the status of modem, it says it is still in LISTENING mode.

Does anyone faced this problem?

Thank you

Hai,
Sometimes I'm getting this response:
OK
ATZ
OK

I found that this command is to restore the user profile.
But I'm not sending this command to modem in mu program. I'm using the modem with C program in linux

Thanks

Check with power supply. Check whether it gives approximate current.

Yes..I'm using 5V--1A aapter and is giving it.
Thanks

Yes..I'm using 5V--1A aapter and is giving it.
Thanks

ponnus

The SIM900 needs a 2amp supply to handle surges when transmitting.
Extra smoothing capacitors are a good idea.

hai,
I used 9V-2A adapter...Still facing the same problem after 5-10 minutes. Is it a network problem? But server is still in listening mode..It can receive data only if I power OFF it,ON it again and configure as server again. In that case the IP will be changed.

Thanks

Hai,
I've solved the problem partially.

I was using multi connection using my SIM900 server. The problem was due to continuous multiple connections from client, because of this the server get stuck. So, I've to restart the modem. i.e, each time when the client needs to send data, it establishes a connection, and close it after sending data. The client needs to send data continuously, so establishing and closing connections continuously. This caused multiple connections and the server get stuck after some data transfer.

Now,I am maintaining a single connection between client and server, and I'm not closing the connection once it is established. If somehow the connection is closed, the client will re-establish the connection.

But,sometimes the client is not able to re-establish a connection,as the server no more accept client connections, while the status shows it is still in listening mode. But, now if reconfigure the server,without restarting the modem, client can connect to new server.

But,the problem is that I am not able to know when the server get stuck. Even if the server don't accept the incoming connections, the status shows it is still in LISTENING mode.

Thanks

I have not used SIMCOM modem as server personally.. but this kind of problem only simcom can answer you better coz their TCP stack may have problems and you cannot be sure of where things are going wrong.

hai,
I've told the vendor about this. They said all of their customers are using SIM900 modem as client only and hasn't reported any problem.

Now, I found a way to check the status of SIM 900 server, even if it hangs.
I am making a client connection from the same modem to the server (server and client are on the same modem).
So, if the server is not available (when it hangs and shows it is in LISTENING mode), AT+CIPSTART command will immediately return ERROR. So, that problem is solved.

But, the server hangs only when there is multiple continuous connections from a client (any client,can be ethernet client). To avoid multiple connections from client, I'm creating one connection at first and continuously writing to that socket. But, then I don't know if the server fails.

Do you know how to check the server is available without starting a new connection?

Writing to a socket(from client) which is down aborts the program.

Thanks

there is no way to check if server is available unless you try to connect it. So i guess SIMCOM has some bugs in modem which they dont know or dont want to know and giving invalid excuses.