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Help me with WinCE based chat software and some issues concerning SIM300

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Newbie level 4
Sep 9, 2009
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Hi all,

I'm trying to create simple chat software on PNA(WINCE 5) device that has a SIM300 Modem internally.
Also I've created a server software on PC.
My server software uses Winsock control and is written in VB6.
Server sends "CMD:pING" to PNA every 30 Seconds. My PNA gets it as a client, and sends response command "CMD:ACK" to the Server.
I do this to check the connectivity in both Client(PNA) and Server(PC).

My problem is on client side(PNA). after a while i receive SEND FAIL on PNA for each data that i send via AT+CIPSEND command. sim300 could receive the data comes from server but for each AT+CIPSEND i receive SEND FAIL. the problem remains also by exiting the application and run it again on PNA. when i hard-reset the device it works fine but same problem will occur after several pinging.

I have these questions :
1 - What makes sim300 to get SEND FAIL?
2 - Does sim300 has a Reset command (instead of reseting the PNA device) ?
3 - Is there a better way to check the connectivity (instead of Pinging) ?

Also I've attached a simple server software that I wrote, to work with GPRS modules. Hope to be useful to someone.

Thanks in advance

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