I want to do serial port communication with a machine which uses RS232-USB ports. I am using serial port class. I am very new to the concept. In my first Machine interfacing I only had to do the serialport.readLine( to get the readings from the machine and there was no need to send ACK /NAK). but for the new machine interface the document says following things:
The following is an example of the RA500 communication:
Computer :<05h 31h 0dh>
RA500 :1st line of information
Computer :<06h 0dh>
RA500 :2nd line of information
Computer :<06h 0dh>
RA500 :”EOF”<0dh>
What i understood from this is i have to write to comport before reading from it. this is what i am doing in my code:
ACK = "06 0d"; NAK = "15 0d"; str = "05 31 0d";
while (count <= 5)
{
rx = ComPortDataReceived(str);
if (!string.IsNullOrEmpty(rx))
{
str = ACK;
returnReading += rx;
}
else if (string.IsNullOrEmpty(rx)) str = NAK;
count++;
}
private string ComPortDataReceived(string str)
{
string Rx = string.Empty;
string exceptionMessage = string.Empty;
try
{
byte[] bytes = str.Split(' ').Select(s => Convert.ToByte(s, 16)).ToArray();
comPort.Write(bytes, 0, bytes.Length);
Rx = comPort.ReadExisting();
PEHRsLibrary.writeTextFile(DateTime.Now + " RxString :" + Rx);
return Rx;
}
catch(Exception e){}
when i use this code i am receiving empty strings as responce. but if i use comPort.ReadExisting() only without using comPort.Write i am receving a string with all the readings but the probblem is it only gives one line of information and dosnt give 2nd or 3rd line readings.
when i try using comPort.ReadLine() after Write() I am getting Timeout exception.
i dont know what i am doing wrong in this case. I am writing ACk after receving 1st line but not receving 2nd line. Next thing i am gonna try is read() as byte and then convert it to string instead of using ReadExisting(). Any other way i can do this?
