[fpc-pascal] Serial to TCP gateway in FPC?

[Bo Berglund]

On Tue, 20 Jun 2017 09:18:50 +0000, Mark Morgan Lloyd
<markMLl.fpc-pascal at telemetry.co.uk> wrote:

>I tend to use the lower-level serial.pp unit. The patches I contributed 
>a couple of years ago specifically added a couple of read-with-timeout 
>functions.
>
Mark, thanks for your input!

I had a look at the serial unit and I found that there are two
overloaded functions SerReadTimeout():

function SerReadTimeout(Handle: TSerialHandle; var Buffer; mSec:
LongInt): LongInt;

function SerReadTimeout(Handle: TSerialHandle; var Buffer: array of
byte; count, mSec: LongInt): LongInt;

In the second of them there is a count argument, presumably indicating
the number of bytes to read from the port. The first is missing this
but sets the value to 1 in the call to ReadFile.

Does this mean that it will only read a single byte and return it
whereas the second version reads the indicated number of bytes and
then returns?
I assume that for both there is a return forced when the timeout
expires.
In both cases the number of actually read bytes are returned in the
result.

Questions:
----------
Do I have to create a thread in order to constantly monitor the state
of the reception?
And I could not find a way to set the comm buffer size, what happens
if I do not check incoming data for a while when there is an inbound
stream. Is there an overflow somewhere?

Anyway it looks promising so far, now I just have to find the proper
TCP client component to use as the far end of the link.
I have used Indy components in the past but I would like something a
bit simpler to use...


-- 
Bo Berglund
Developer in Sweden