CODEWITHSUNDEEP
windowsdelphi
user295156
user295156

Reputation:

Reading binary data from serial port using Dejan TComport Delphi component

Apologies for this question but I am a bit of a noob with Delphi. I am using Dejan TComport component to get data from a serial port. A box of equipment connected to the port sends about 100 bytes of binary data to the serial port. What I want to do is extract the bytes as numerical values into an array so that I can perform calculations on them.

TComport has a method Read(buffer,Count) which reads DATA from input buffer.

function Read(var Buffer; Count: Integer): Integer;

The help says the Buffer variable must be large enough to hold Count bytes but does not provide any example of how to use this function. I can see that the Count variable holds the number of bytes received but I can't find a way to access the bytes in Buffer.

TComport also has a methord Readstr which reads data from input buffer into a STRING variable.

function ReadStr(var Str: String; Count: Integer): Integer;

Again the Count variable shows the number of bytes received and I can use Memo1.Text:=str to display some information but obviously Memo1 has problems displaying the control characters. I have tried various ways to try and extract the byte data from Str but so far without success.

I am sure it must be easy. Here's hoping.

Upvotes: 2

Views: 9789

Answers (2)

NeoPOS
NeoPOS

Reputation: 136

// I use a timer to read a weight coming in on the Serial Port
// but the routing could also be triggered by OnRXChar (received data event)
// or OnRXBufferFull event.

var
  WeightString: String; //global

procedure TfmUDF.tmScaleTimer(Sender: TObject);
var
  Data: AnsiString;
begin
  ReadStr(Data,Count); //the individual bytes can be read Data[n].....
  WeightData:=WeightData+Data; //just keeps adding the incoming data
end;

Does this help?

Upvotes: 0

Daniel Luyo
Daniel Luyo

Reputation: 1336

In this function 

function Read(var Buffer; Count: Integer): Integer;

The Count parameter is the number of bytes you expect to read. While the function return value is actually read bytes.

If you have a Buffer defined as an array of 100 bytes you can code

x := Read(Buffer, 100);

and if the input is only 70 bytes then x will be 70. That way you can read while x > 0

Upvotes: 2

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