simple serial send/receive problem

Hi,

I’m making a simple network program that uses com1 to send/receive data,

my packet structure is as follows
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
{ D S T <--data load-----------> cs }

D = destination
S = source
T = packet type
cs = check sum
}
The thing is when I send my packet it seems to insert a null character at bit 9 of the packet even thou it's declared as

char packet[16];

Meaning that when I enter 1 - 9 then a letter for the data
it’s received as

packet 1 {??D1234
packet 2 56789w*}

If I send the data packet to HyperTerminal it displays perfectly
so obviously it’s in my receive code... but I have no idea what it is im looking for... :(

Any ideas / thoughts greatly appreciated

Cheers,
Kev

Post a snippet of code.

sorry :)

Code:

---

    if ((cComChar = readcomm()) != 0)  // is a char waiting to be read from port?
      {
         
                if (k <= 15)
                {
                        rxpacket[k] = cComChar; // set first char to that already read
                        k++;
                }else{
                        k = 0;
                }
          rxflag = 1;
          iInput = COM;
          if (iInput == COM)
            {
              //rxpacket[0] = cComChar; // set first char to that already read

              for (iCount = 1 ; iCount < 16 ; iCount++)
                  rxpacket[iCount] = readcomm(); // then read next 15 to make packet

              cDest = rxpacket[1]; // get destination char
              cSource = rxpacket[2]; // get source workstation
              cPktType = rxpacket[3]; // get packet type
             
                          printf("\npacket received: ");
              for (k = 0; k <= 15; k++)
                {
                  printf("%c", rxpacket[k]);
                  j++;
                }
                          printf(" End Packet\n");

---

is how i read in the packet

Cheers,
Kev

Hmm, I can't try your code, so I'm going to have to guess. Here's a reworked version based on what you posted.

Code:

---

for (i = 0; (cComChar = readcomm()) != 0; i++)
{
  rxpacket[i] = cComChar;
  if (i == 15)
  {
    /* 16 bytes received, process complete packet */
    cDest    = rxpacket[1]; /* get destination char  */
    cSource  = rxpacket[2]; /* get source workstation */
    cPktType = rxpacket[3]; /* get packet type        */
    printf("\npacket received: ");
    for (k = 0; k < 16; k++)
    {
      printf("%c", rxpacket[k]);
    }
    i = -1; /* Reset i, this allows use to get a new packet */
  }
}

---

thanks ill have a go at that :)

I would have posted all the code but its near on 700 lines :(

not sure it would have been apprecaited :)

EDIT: Solved

The problem came down to timing :/
I dropped in a wait function after each read from the COM port and low and behold the packets were all present and correct :)

Thanks again for the help :)

Cheers,
Kev