[time-nuts] Trimble Thunderbolt Rs-232 Levels

Hal Murray hmurray at megapathdsl.net
Wed Feb 13 01:04:56 EST 2008


> I think I will apply power to the module and measure the levels from
> the port.  If it is TTL out, I will need to do a level shift anyway
> to give the computer proper voltages to run it's serial port. 

Most RS-232 level shifters also include an inverter.

I'd just plug it in and see if it works.  Especially if it has a DB-9.

Ages ago, RS-232 specs called for 12 V.  I think they updated it to work at 
6V.

In practice TTL signals actually work, at least if you aren't using long 
cables.  All the receiver chips I've checked have had an input threshold at 
roughly the TTL switching level - 2 diode drops above ground.



-- 
These are my opinions, not necessarily my employer's.  I hate spam.






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