Sending SMS via AT+CMGS command programatically - c

Question

I'm trying to send SMS via MC7304 modem programatically in C++. For AT command, linux share /dev/ttyUSB1 port. Here is my code:
fd_set readSet, writeSet;
struct timeval timeval;
int cellFd = open("/dev/ttyUSB1", O_RDWR, 0);
writeSet = readSet;
timeval.tv_sec = 0;
timeval.tv_usec = 3000000;
int n = 0;
int written = 0;
int readed = 0;
int totalRead = 0;
char buffer[1001];
memset(buffer, '\0', 1001);
written = write(cellFd, "AT+CMGF=1\r\n", 11);
printf("AT+CMGF=1 command sent with result: %d. Waiting for response...\n", written);
while(true)
{
FD_ZERO(&readSet);
FD_SET(cellFd, &readSet);
timeval.tv_sec = 2;
timeval.tv_usec = 0;
n = select(cellFd + 1, &readSet, &writeSet, NULL, &timeval);
if(n == 0)
{
break;
}
else if(n > 0)
{
readed = read(cellFd, buffer + totalRead, 1000 - totalRead);
totalRead += readed;
}
else
{
printf("Error\n");
exit(0);
}
}
if(totalRead > 0)
{
cout << buffer << endl;
}
else
{
printf("No data received\n");
}
totalRead = 0;
readed = 0;
memset(buffer, '\0', 1001);
written = write(cellFd, "AT+CSCS=\"GSM\"\r\n", 15);
printf("AT+CSCS=\"GSM\" command sent with result: %d. Waiting for response...\n", written);
while(true)
{
FD_ZERO(&readSet);
FD_SET(cellFd, &readSet);
timeval.tv_sec = 2;
timeval.tv_usec = 0;
n = select(cellFd + 1, &readSet, &writeSet, NULL, &timeval);
if(n == 0)
{
break;
}
else if(n > 0)
{
readed = read(cellFd, buffer + totalRead, 1000 - totalRead);
totalRead += readed;
}
else
{
printf("Error\n");
exit(0);
}
}
if(totalRead > 0)
{
cout << buffer << endl;
}
else
{
printf("No data received\n");
}
totalRead = 0;
readed = 0;
memset(buffer, '\0', 1001);
written = write(cellFd, "AT+CMGS=\"MY_NUMBER\"\r\n", 24);
printf("AT+CMGS=\"+MY_NUMBER\" command sent with %d result. Waiting for response...\n", written);
while(true)
{
FD_ZERO(&readSet);
FD_SET(cellFd, &readSet);
timeval.tv_sec = 3;
timeval.tv_usec = 0;
n = select(cellFd + 1, &readSet, &writeSet, NULL, &timeval);
if(n == 0)
{
printf("No data\n");
break;
}
else if(n > 0)
{
memset(buffer, '\0', 1001);
readed = read(cellFd, buffer, 1000);
for(int i=0; i<readed; i++)
{
printf("%02x ", buffer[i]);
}
printf("\n");
cout << buffer << endl;
if((*(buffer) == 0x3E) && (*(buffer + 1) == 0x20) && (*(buffer + 2) == 0x0A))
{
written = write(cellFd, "Test\x1A", 5);
printf("SMS text sent with %d result. Waiting for response...\n", written);
}
}
else
{
printf("Error\n");
exit(0);
}
}
The first two commands work fine and returning 'OK' response. Unfortunetly, after sending AT+CMGS command, modem response with 0x0A (line feed) twice, next responsing with 0x3E 0x20 0x0A (> ) (that looks ok). After this sequence, i'm sending text that ends with 0x1A (CTRL-Z), but modem still responding with >. This situation repeats hundreds of times and at the end I got error +CMS ERROR: 305. It looks like:
root#Moxa:/home/SMS# ./SMS
AT+CMGF=1 command sent with result: 11. Waiting for response...
OK
AT+CSCS="GSM" command sent with result: 15. Waiting for response...
OK
AT+CMGS="(SOME NUMBER)" command sent with 24 result. Waiting for response...
>
SMS text sent with 5 result. Waiting for response...
>
[ situation repeats ]
SMS text sent with 5 result. Waiting for response...
+CMS ERROR: 305
What's wrong with this code, how can I fix it?