Sending +++ to modem

[micknfld]

I have a PIC connected to a modem. I use the modem to call another computer to transfer data to it. I am able to connect to the other computer and successfully send data to it. However, I am unable to use the +++ command to return to command mode to hang up the line. The following is part of my code:

fprintf(modem,"atdt,8959%c",13);
fprintf(modem,"data");
fprintf(modem,"+");
fprintf(modem,"+");
fprintf(modem,"+");
fprintf(modem,"ath0%c",13);

I saw a posting on this forum that said that you need to put a delay between the +'s. I tried putting a 150ms delay between the +'s and then a 500ms delay before sending the ath0 command. This didn't work. A also just tried fprintf(modem,"+++") but this didn't work either.

The problem is that the modem just takes the +++ and ath0 and sends it to the other computer as data and the modem remains off-hook.

Any suggestions?

[Mark]

Try sending

fprintf(modem,"+++");

After you send the "+++" you will need to wait for a response from the modem. If you send data then the modem will think that you are trying to send "+++ath0\n" as though it was data. For starters try this:

fprintf(modem,"+++");
delay_ms(1000);
fprintf(modem,"ath0%c",13);


Once you see that it works, take out the delay and look for a response.

[asmallri]

You need 1 second of "silence" before sending the +++ sequence.
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Regards, Andrew

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[King Virus]

...or you pull down the CTS Line. In standart configuration the modem should interpret this as ATH !
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[StuartH]

[micknfld]

I put a delay of 1 second before sending the +++ sequence. That worked. Thanks.

[King Virus]