[ntp:questions] NTP sever on an isolated Network

David J Taylor david-taylor at blueyonder.neither-this-bit.nor-this.co.uk
Thu Jan 15 08:57:49 UTC 2009


Unruh wrote:
[]
> Yes, but that same manual says that the voltage for the 18PC version
> is 8-30V. It says nothing about the internal voltage being the 4.5 to
> 5.5 V.
> And the 18PC and the 18LVC are different units with different inputs
> and
> outputs.
> The PC is also the one with serial port output and the serial port
> standard
> says that the voltage is -12 to 12V on the serial pins. Now, many
> serial cards
> do accept 0-5V (TTL) which is why the 18LVC works on many serial ports
> without a voltage converter,  but that is out of standard. Does the
> 18PC follow the standard? The manual does not say. Ie, there is
> NOTHING in the manual which
> would allow one to conclude that the actual voltage delivered to the
> unit
> is 5V rather than the 8-30 V that the manual does say that the unit
> requires. You might be right that a) it is the lighter adapter than
> lowers
> the voltage to 5V, and b) that the output does not follow the serial
> port
> standard of -12 to 12V, but I would like something other than your
> speculations to go by.

Bill,

Section 1.4.2 of the manual says that the RS-232 levels sent are 0..+5V 
for the PC version, and from 0..Vcc for the LVC version, where Vcc is the 
supply voltage.

I would be surprised if the internal electronics differed significantly 
between the PC and the LVC.

Cheers,
David 




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