On Wed, 24 Jan 2001, Segfault wrote:

> Hi all,
> 
> I'm trying to make a UPS package I found for FreeBSD (which I used to use
> on a PC) to work on my Mac Quadra 605.
> 
> What the program does is monitor and alter the signal level of specific
> pins of a serial port connected to the UPS.
> 
> >From the source, the various ports monitored or changed are RTS, DTR, RNG
> and other pins (TIOCM_RTS, TIOCM_DTR and TIOCM_RNG respectively).
> However, I don't know which pins are mapped to which. PCs have pins
> labeled as RTS, CTS, DSR, DCD, TxD and RxD but Macs have round serial
> port connectors with pins labeled as HSKo, HSKi, TxD-, RxD-, TxD+, GPi
> and RxD+ instead.

I'm a little confused. I'd expect the UPS to be telling you what is going
on, but RTS and DTR are outputs - i.e. if we're talking about the Mac,
they are outputs from the mac to the UPS. Which seems backwards.

Pin mapping will really depend on the cable you're using, so I'll just go
over which pins NetBSD worries about, and let you deal with your
cable. :-)

HSKo == DTR
HSKi == CTS
GPi  == DCD
TxD+ == unused		Note that TxD+/- form a differential pair
TxD- == TD		which helps get better signals strength
RxD+ == connect this to ground
RxD- == RD		RxD+/- are also a differential pair

> Therefore, I would like to know which pins are mapped to which. For
> example, if I checked the signal level of the pin "RTS", which pin on my
> Mac would actually be checked?

Note: RTS isn't an output on Mac Serial ports.

Here's where I'm confused. Your software should be DRIVING the levels of
output pins, not checking them. :-) I'd expect that you'd really look at
are the inputs.

Take care,

Bill