[time-nuts] Timelab, two SR620s and losing samples
Poul-Henning Kamp
phk at phk.freebsd.dk
Sun Jan 17 12:45:26 UTC 2016
--------
In message <569B8B2E.5070604 at rubidium.dyndns.org>, Magnus Danielson writes:
>>> I think you should develop that line of thought, to detail why it helps
>>> on GPIB and why not on serial.
>>
>> It's really very simple: RS-232 sends blind, you don't even need to
>> know if there is a receiver or what it does. If the receiver cannot
>> keep op, data is simply lost.
>>
>> GPIB handshakes every byte, so the actions of the receiving end affects
>> the transmitting end - in particular if the receiver cannot keep up.
>
>OK, you where thinking about the flow-control.
>
>You can have RS-232 wired up to do flow-control (hardware-flow-control),
But the important point is you don't have to do that, all you need
is two wires: GND-GND and TXD->RXD
With GPIB that option does not exist, sender and receiver are always
in lock-step.
Therefore, talk-only mode is a big advantage in terms of decoupling
on RS-232 and makes almost no difference on GPIB.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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