[fpc-pascal] USB serial interface

[Marco van de Voort]

> Am Dienstag, 26. Dezember 2006 18:57 schrieb Marco van de Voort:
> > > The best USB-serial Interfaces for Linux are the ones with FTDI Chip
> > > inside. http://www.ftdichip.com/
> > > http://www.ftdichip.com/Products/EvaluationKits/USB-Serial.htm
> >
> > Do they have the same latency as a normal serial port? I've tried several
> > usb-serial ports, and they all have horrible latencies compared to an
> > onboard (or PCI card).
> >
> For me the latency is not (very) important. I do not feel a lack of latency.
> We tried USB converters with prolific chipset and it hangs up then, so FTDI 
> chips would be better. I read also somewhere a lack of latency. May be it is 
> also a question of the Kerneldriver and the driver will improve more in the 
> future.

We mostly use a serial (either using a RS422 converter or straight) to
contact a PIC for the realtime part of our applications. The latency is also
there under Windows, and messes up the realtime aspect of signaling. 
(actually, while I used the converters under Linux, I
haven't latency benchmarked them yet)