[time-nuts] Timelab, two SR620s and losing samples

Poul-Henning Kamp phk at phk.freebsd.dk
Sun Jan 17 07:45:26 EST 2016


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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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