[ntp:questions] ntp server specs

Chris Albertson albertson.chris at gmail.com
Wed Jun 15 20:36:37 UTC 2011


One hundred??

Best to use a decentralized design.  Buy 100 rs442 to rs232 receiver
chips.  You can place then in a box on the back of each of the 100
computers.

The specs say one 442 driver can connect to ten receivers.  So you'd
need a ten port distribution system to drive 10 buses.

Please remind us why you can't use NTP.  It would be less work to buy
a 100 port Eithernet hub.  You can get very good timing with NTP on a
short run of 100BaseT


On Wed, Jun 15, 2011 at 11:44 AM, E-Mail Sent to this address will be
added to the BlackLists <Null at blacklist.anitech-systems.invalid>
wrote:
> David J Taylor wrote:
>> "C BlacK" <rblak at non.net> wrote in message
>>> For our discussion, lets say there are many machine
>>> but the distance is not going to me more that 100ft.
>>
>> Then some top-of-the head sums might be:
>>
>> 100 machines - RS-232 input resistance, guess, 4K,
>>  all 100 in parallel 40 ohms.
>
> A 5v PPS signal with more than 125ma drive?
>  Not likely from a normal TTL chip.
>
> 100 PC RS232 serial ports tied together,
>  fed from one PPS driver?
>
>  I'd think you would have a lot of stray ground currents
>  running around.
>
>  Even if they were isolated RS422/485 receivers,
>   100 in parallel, fed from one PPS driver,
>   seems like it would be problem prone.
>
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-- 

Chris Albertson
Redondo Beach, California



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