Luca Olivetti wrote:
Al 04/07/13 17:24, En/na Mark Morgan Lloyd ha escrit:
In any event, my experience is that USB->serial converters are very poor
for anything that involves accurate timing, and I suspect that
controlling a 485 transceiver in conjunction with one would be
problematic.
Not if the converter manages the rx/tx switching all by itself
I think I asked FTDI about this a couple of years ago, and
was told that their hardware had facilities that would help but
exploiting them would take a non-standard driver.
The ones I used worked with the standard driver: send something, it
automatically enables the transmitter, after the last bit has been
transmitted it goes in high impedance mode ready for listening/receiving.
Yes, but I was considering the case of using an off-the-shelf USB->RS232
device, followed by an RS232->RS485 converter (OP's note of this morning).
A couple of years ago I was reverse-engineering the protocol used by
some HP protocol analysers (so that I could use them for
reverse-engineering protocols...) and my initial hack used a couple of
standard USB devices. Unless I slowed the data stream right down (300
Baud) the driver buffering messed things up to the extent that I
couldn't determine where there were gaps, let alone measure them so I
could work out what the timeouts were.
--
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk
[Opinions above are the author's, not those of his employers or colleagues]
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