On 2014-04-09, E-Mail Sent to this address will be added to the BlackLists <Null@BlackList.Anitech-Systems.invalid> wrote: > On 4/8/2014 2:57 PM, William Unruh wrote: >> On 2014-04-08, <a.everett....@gmail.com> wrote: >>> >>> Also, as previously mentioned, >>> simply feeding a 3.3V or 5V pps output from a GPS receiver >>> into a RS232 port will not work as the voltage levels are different. >>> You will need a simple TTL logic to RS232 converter such as a MAX232 >>> device to convert the PPS output signal to the correct voltage level. >>> >> Actually false form most serial ports these days. While the standard >> says 5V the actuallity is that 3,3 V will trigger it on almost all >> serial ports. Ie, in general it is a non-issue. Note that the fact that >> serial and parallel ports and their interrupts are disappearing from >> almost all computer is probably a bigger problem. > > The current version is TIA/EIA-232-F (circa 1997, last updated 2002?)
And this is irrelevant. The question is not what the standard says but what the serial ports actually handle. Again, does anyone know of a serial port which does NOT handle TTL logic imputs? ><BlockQuote> > Electrical Specification > A logic 0 is represented by a driven voltage between 5 V and 15 V > and a logic 1 of between ?5 V and ?15 V. > At the receiving end, a voltage between 3 V and 15 V represents a 0 > and a voltage of between ?3 V and ?15 V represents a 1. > Voltages between ?3 V are undefined and lie in the transition region. > This effectively gives a 2-V minimum noise margin at the receiver. ></BlockQuote> > > I've used some current TI (RS232-F speced), > that don't switch if the voltage remains positive; > However I have also used some current Maxium that switch at ~ 1.5 V. > > I haven't really seen this change much in the last two years, > however I certainly could be missing out on some modern chipset's RS232 > features. > > _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
