Artema Hybrid communication with c++ on Linux - c++

Question

I am currently trying to integrate a POS system with an Artema Hybrid CC handheld. I am wondering if anyone else has worked on this or something similar.
I can read from the device, that is I receive the ENQ, and send back an ACK in a thread, and I keep it open for reading/writing, but everything I try to write from it simply does nothing.
Here is the code for the function to write the data:
void PayLife::sendPayLifeData(QString data) {
int len = data.length();
int i = 0;
char lrc = 0;
char stx = 0x02;
char etx = 0x03;
char ack = 0x06;
char * bytes;
int ret;
char buffer[132];
bytes = (char *) malloc(sizeof(char) * len + 10);
strcpy(bytes,data.toLatin1().data());
qDebug() << "PayLife Sending data: " << data << " of len " << QString::number(len) <<
" " << " Bytes is: " << bytes ;
while (i < len) {
lrc ^= bytes[i];
i++;
}
/* sprintf(buffer,"%c%c%s%c%c",ack,stx,bytes,etx,lrc);
for (i = 0; i < strlen(buffer); i++) {
printf("c: %X ", buffer[i]);
}
printf(" [[ %s ]] \n", buffer); */
qDebug() << "Starting";
write(this->descriptor,&ack,1);
usleep(100000);
write(this->descriptor,&stx,1);
usleep(100000);
ret = write(this->descriptor,bytes,132);
usleep(100000);
write(this->descriptor,&etx,1);
usleep(100000);
write(this->descriptor,&lrc,1);
qDebug() << "Done";
free(bytes);
}
The data argument is: E11U000008507000099VZ000000
Of course, the documentation is in German, which I don't speak, so this is as far as I have gotten. I've basically got 1 month to implement this then I have to give the device back.
If anyone has any pointers, or some example code that would be awesome.
/jason

Answer 1

The transport protocol looks like something standard, so maybe you should only send len bytes of the data not 132 and include the ETX character in the lrc summing ?
It might be easier and clearer to use QByteArray instead of malloc arrays or QString (QString are for user displayed strings which is not the case here):
void PayLife::sendPayLifeData(const QByteArray & data) {
static const char stx = 0x02;
static const char etx = 0x03;
static const char ack = 0x06;
QByteArray buffer = stx + data + etx;
// Calculate the xor sum on data + etx
char lrc = 0;
for(int i = 1; i < buffer.size(); ++i) {
lrc ^= buffer[i];
}
buffer += lrc;
qDebug() << "Starting";
write(this->descriptor, &ack, 1);
write(this->descriptor, buffer.data(), buffer.size());
qDebug() << "Done";
}
You should also have a look at QSerialDevice, it could allow you to implement the protocol in a more event driven way with signal and slots.