HI, another issue now, im using the VDIP USB device to write to a USB drive.
Im collecting data from another part of the program using
float PosRead[20] and float Reading[20] variables.
im then concating this info to USBtx which is then sent to the function USBwrite (String USBtx)
I now people dont like strings on here but im still learning and this is the only way i can get this info into the USB stick as far as i know.
the code is running and im getting this info back from the serial port
Serial No. 63214563
0 0.00 639.00
1 4.96 639.00
2 9.93 639.00
3 15.02 639.00
4 19.98 639.00
5 25.07 639.00
6 29.91 639.00
7 35.00 639.00
8 40.09 639.00
9 45.06 639.00
10 49.90 639.00
11 54.99 639.00
12 59.95 639.00
13 65.04 639.00
14 70.01 639.00
15 75.10 639.00
16 79.94 639.00
17 84.91 639.00
18 90.00 639.00
The above is array position , Posread, Reading
63214563,0.00,639.00,4.96,639.00,9.93,639.00,15.02,639.00,19.98,639.00,25.07,639.00,29.91,639.00,35.00,639.00,40.09,639.00,45.06,639.00,49.90,639.00,54.99,639.00,59.95,639.00,65.04,639.00,70.01,639.00,75.10,639.00,79.94,639.00,84.91,639.00,90.00,639.00
this iswhat i get from the Serial.println(USBtx) using the code supplied below.
6 is what is returned when i use the last line Serial.println(sizeof(USBtx);
this doesn't seem right, i tried using the dtostrf(Reading[k],6,2,temp) with char temp[6] in a for next loop of k ( k was 19) to convert the float info to strings the concat them to USB but it stopped after 3 lines
e.g
63214563,0.00,639.00,4.96,639.00,9.93,639.00
what am i doing wrong? 
as i said before im a noobie still.
//**************************** Convert dat to string for usb
void USBconv(int x) {
Serial.println("converting!");
Serial.println(x);
Serial.print("Serial No. ");
Serial.println(serialNo);
USBtx += serialNo;
for (int k = 0; k < x; k++) {
Serial.print(k);
Serial.print(" ");
Serial.print(PosRead[k]);
Serial.print(" ");
Serial.println(Reading[k]);
USBtx += ",";
USBtx += PosRead[k];
USBtx += ",";
USBtx += Reading[k];
}
USBwrite(USBtx);
Serial.println(USBtx);
Serial.println(sizeof(USBtx));
}
//******************************usb
void USBwrite(String USBtx) {
int NumBytes = (sizeof(USBtx));
Serial1.print("OPW "); // open file of if not create file
Serial1.print(serialNo);
Serial1.print(".csv");
Serial1.print(" ");
Serial1.print(USBdate, HEX); // set file date
Serial1.print("\r");
delay(100);
Serial1.print("WRF "); // write data to file angle,pressure, for csv formating
Serial1.print(NumBytes);
Serial1.print(USBtx);
Serial1.print("\r");
delay(100);
Serial1.print("CLF "); // close file
Serial1.print(serialNo);
Serial1.print(".csv");
Serial1.print("\r");
delay(100);
}
