[fpc-pascal] Reading Serial Hex Data

[Bo Berglund]

On Sun, 27 Dec 2020 21:15:03 +0100, Jean SUZINEAU via fpc-pascal
<fpc-pascal at lists.freepascal.org> wrote:

>I think TBlockSerial can work in your console program  context. May be 
>TLazSerial can be more tricky to use in your context, you'll need to use 
>events/callbacks and FCL.

I have struggled with LazSerial in a console program and it just is
not intended for that usage. Won't work. Throws exceptions if run in a
device without a GUI like a Linux server.

But instead I used the built-in serial unit and packaged the whole
reading stuff into a thread that will read the serial line constantly
using the blocking read and supply the data to the main application as
it arrives.
Not a big deal to do and get working. You need a read timeout in the
execute loop so that the thread can detect if it has been commanded to
terminate, that is all I think.

Also, for the OP:
What do you mean by receiving hex data? Are you saying that you
receive byte data as 2-character ASCII hex code?
I.e. every byte you want to receive is represented by *two* characters
in the incoming stream?

In that case if you are not using any delimiters you will probably
soon be out of sync and mixing most and least significant hex
characters in the transmission so that for example 1a 2b 3c could
become ..1 a2 b3 c..

Very dangerous situation. You really must use some kind of delimiter
in the data flow...


-- 
Bo Berglund
Developer in Sweden