Quectel EC25 Sending SMS and getting +CMS ERROR 305

Question

This code sends some of SMS messages. But it gives error for some of the messages. It may about some wrong character that GSM module does not recognize like `(. Is there any one can help to fix the code. I am checking if GSM device is attached to ttyUSB2. This is C++ code.

int sendSms(UsbPort &device, string phoneNumber, string message) {

    char buf[MAXBUF] = {0};
    int n;

    if(device.fildes > 0) {
        int max_check = 0;

        if (write(device.fildes, "ATZ\r", 4) < 4) {
            printf("ATZ write error - %s \n", strerror(errno));
            return -1;
        }

        this_thread::sleep_for(chrono::seconds(1));

        if (write(device.fildes, "AT+CMGF=1\r", 10) < 10) {
            printf("AT+CMGF=1 write error - %s \n", strerror(errno));
            return -1;
        }

        if (tcdrain(device.fildes) != 0) {
            perror("tcdrain() error");
            return -1;
        }

        this_thread::sleep_for(chrono::seconds(1));
        bzero(buf, sizeof(buf));
        read(device.fildes, buf, MAXBUF - 1);
        cout << "Buffer-1 = " << buf << endl;

        if (write(device.fildes, "ATE+CSMS=1\r", 11) < 11) {
            printf("ATE+CSMS=1 write error - %s \n", strerror(errno));
            return -1;
        }

        if (tcdrain(device.fildes) != 0) {
            perror("tcdrain() error");
            return -1;
        }

        this_thread::sleep_for(chrono::seconds(1));
        bzero(buf, sizeof(buf));

        if ((n = read(device.fildes, buf, MAXBUF - 1)) > -1) {
            int length = strlen(buf);
            cout << "length = " << length << endl;
            buf[length] = '\0';
            cout << "Buffer-2 = " << buf << endl;
            if (strstr(buf, "+CSMS:") != NULL) { // Ready to send SMS
                cout << "Can send SMS: " + string(buf) << endl;
                // Send SMS
                string data1 = "AT+CMGS=\"" + phoneNumber + "\"\r";
                if (write(device.fildes, data1.c_str(), data1.length()) < data1.length()) {
                    printf("AT+CMGS write error - %s \n", strerror(errno));
                    return -1;
                }
                else {
                    this_thread::sleep_for(chrono::seconds(1));
                    string data2 = message + "\x1A";
                    if (write(device.fildes, data2.c_str(), data2.length()) < data2.length()) {
                        printf("ATE+CSMS=1 write error - %s \n", strerror(errno));
                        return -1;
                    }

                    if (tcdrain(device.fildes) != 0) {
                        perror("tcdrain() error");
                        return -1;
                    }

                    this_thread::sleep_for(chrono::seconds(1));
                    bzero(buf, sizeof(buf));
                    if ((n = read(device.fildes, buf, MAXBUF - 1)) > -1) {
                        int length = strlen(buf);
                        cout << "length = " << length << endl;
                        buf[length] = '\0';
                        cout << "Buffer-2 = " << buf << endl;
                        if (strstr(buf, "OK") != NULL) {
                            cout << message + " sent to : " + telNo + " successfully." << endl;
                            return 0;
                        }
                    }
                    else {
                        cout << message + " sent to : " + telNo + " unsuccessful!" << endl;
                        return -1;
                    }
                }
            }
            else {
                cout << "Error: buf = " + string(buf) << endl;
                return -1;
            }
        }
    }
    return -1;
}

this is the example of which it cannot send sms.

Actually `(` and `)` characters do belong to GSM charset. Could you please edit your question so that the output log is in text form instead of an image? — Roberto Caboni, Feb 09 '21 at 15:11
Please, post the entire output of `sendSMS` function. And, please, specify also: 1) how is `MAX_BUF` defined? Could you print separately the contents of `message` and also the value of `data2.length()`? What happens if you insert a shorted message, let's say the substring before `Alarm`? — Roberto Caboni, Feb 09 '21 at 15:26
Finally: could you post the response of the command `AT+CLAN?`. — Roberto Caboni, Feb 09 '21 at 15:36
We found the problem. It is not about ASCII characters. It is about message longer than it should be. We need to Send Sms as Concatenated SMS. Thanks for your responses. — FSA, Feb 12 '21 at 11:24
It was exactly my assumption, that's why I asked those question in my previous comments. — Roberto Caboni, Feb 12 '21 at 11:30

score 1 · Accepted Answer · edited Feb 13 '21 at 22:20

1

The problem was not about ASCII characters, but about sending a message longer than it should be.

When we use Concatenated SMS it solved our problem. It Send Sms without problem.

AT+CGMF=1
AT+CSCS="GSM"
AT+CSMP=17,167,0,241
AT+CMGS="Number"
> Message <CTRL+Z>

edited Feb 13 '21 at 22:20

Roberto Caboni

7,252
10
25
39

answered Feb 12 '21 at 11:27

FSA

67
9

Quectel EC25 Sending SMS and getting +CMS ERROR 305

1 Answers1