HP50G and RS232
David
port but not the USB port. How could I 'talk' separately to devices on each
port? Is it a flag setting in conjunction with the OPENIO command or is
there a new command just for the RS232 port?
I have seen in the newsgroup that an adaptor/cable for the new port isn't
available. Is this true? If so how does HP expect owners to use it?
Finally, sorry about the long list of questions, but does anyone know where
I can find more details on this particular implementation of 'RS232' eg
voltages, max data rates, which wire does what?
Many thanks
mats
> [...] but does anyone know where
> voltages, max data rates, which wire does what?
already
http://groups.google.com/group/comp.sys.hp48/browse_thread/thread/7696caf664497657
James M. Prange
> Since the HP50g has an RS232 port does anyone know how to open this specific
> port but not the USB port. How could I 'talk' separately to devices on each
> port? Is it a flag setting in conjunction with the OPENIO command or is
> there a new command just for the RS232 port?
As usual, set flag -33 for "Transfer via IR" and clear flag -33
for "Transfer via wire". For the 50g, with flag -33 clear, flag
-78 determines whether it uses USB or the serial port.
> I have seen in the newsgroup that an adaptor/cable for the new port isn't
> available. Is this true?
Apparently so, at least for now.
> If so how does HP expect owners to use it?
Good question! Well, do you have any skills with electronics
projects? You could always design and build your own cable and
adapter.
> Finally, sorry about the long list of questions, but does anyone know where
> I can find more details on this particular implementation of 'RS232' eg
> voltages,
Definitely not "RS232" compatible; the signal levels at the 50g's
serial port are nominally 0V for 0 bits and +3.3V for 1 bits. You
need to invert, shift, and amplify those for EIA-232 transmission,
and vice versa for reception.
> max data rates,
I guess the same as the 48gII's serial port, 115200 bits per
second, but I don't think that I've seen seen that discussed for
the 50g.
> which wire does what?
See:
http://groups.google.com/group/comp.sys.hp48/browse_frm/thread/7696caf664497657/
In general, try:
http://groups.google.com/groups?as_q=50g&as_oq=RS232+RS-232+serial&as_ugroup=comp.sys.hp48
> Many thanks
Many welcomes
--
Regards,
James
David
But why would HP fit a port that is neither the 'correct' voltage, parity
nor is there a cable or adaptor? What do they expect folks to do with this
connection? I must be missing the point. Is there something coming along is
the 2006 version of HP-IL?
"James M. Prange" <jmpr...@i-is.com> wrote in message
news:96212$44f97c5f$4267eade$10...@123.NET...
James M. Prange
> Thanks for the earlier help on this.
You're welcome.
> But why would HP fit a port that is neither the 'correct' voltage,
Well, probably most people would choose to use the USB and IrDA
ports instead, even if the serial port were the correct voltage
for EIA-232, and making it EIA-232 compatible would cost extra,
so....
But note that for connecting the 50g to other devices which use
the same signal levels (and there are some), the voltage is
correct as is, and otherwise a level-shifter would be needed for
that.
Of course, HP certainly shouldn't be calling it "RS232".
> parity
Huh? As far as I know, the same parity options are available in
the 50g as are available in all previous models with a serial
port. The 49g+ even allows using parity for the IrDA port. Why
would HP remove that?
That said, I don't actually have a 50g, so I can't very well check
whether parity still works. If and when I get a 50g, I'll check
that.
And I never have understood why HP, starting with the 49G, removed
the XON/XOFF software flow control that works so well on the 48
series, so who knows?
> nor is there a cable or adaptor?
Well, I can understand not including it in the package, but I do
think that HP should've at least made it available as an optional
accessory.
> What do they expect folks to do with this
> connection?
My guess is that HP expects this serial port to be used mostly by
professionals, such as surveyors, who (HP hopes) will be willing
to pay a third party to manufacture whatever they need to make the
calculator useful with whatever equipment they want to use it
with.
> I must be missing the point.
Well, at least it seems an improvement over the 49g+; the port is
built-in on the 50g, the remaining problem being that it's up to
the user or a third party to make it more useful.
> Is there something coming along is
> the 2006 version of HP-IL?
<snip>
--
Regards,
James
TW
> professionals, such as surveyors, who (HP hopes) will be willing
> to pay a third party to manufacture whatever they need to make the
> calculator useful with whatever equipment they want to use it
> with.
Yes they are. We plan to do one at the moment we have no cash. Since
we'll begin selling out units in a week or two, in a month or two
you'll have a cable.
TW
James M. Prange
Thanks for the update Tim. I was aware that you guys had (at least
tentative) plans to offer a cable/converter.
I just hope that it will be affordable for us hobbyists who can't
justify it as a business expense.
That said, for those who are skilled in building electronics
projects, building one doesn't seem all that expensive or
difficult. The tricky part would be getting it on a nice neat
little PCB that fits within a connector shell and looking
"professionally manufactured", but something larger that looks
like a prototype would still be functional.
When you have it ready, please post specifications such as the
current draw, whether it includes an automatic powerdown function
when it isn't receiving a valid EIA-232 level signal, and so on.
--
Regards,
James
John H Meyers
> Why would HP fit a port that is neither the 'correct' voltage...
> nor is there a cable or adaptor?
It's the same port that exists on the HP48Gii from this same
calculator series, and is provided by the internal chipset anyway;
a simple "crossover" cable could connect two calcs directly,
and a serial cable for PC
(with a signal converter apparently powered by the PC)
is a standard HP-provided accessory for the 48Gii,
thus providing the only way to transfer files from PC.
For the 49G+, a USB port (and included cable)
provides file transfers (and ROM downloads)
from USB-equipped computers,
so the serial port was dropped and replaced with USB.
In 50G, the original 48Gii serial port was also restored,
for users and third-parties to make use of as they wish,
but since USB (with cable) is already present for file transfers,
adding back the now *optional* port (with battery power
at the connector for cable manufacturers to use)
is as far as HP goes.
This seems much the same as with most DVD players,
which come with basic video/audio cables only;
there are also extra high-def video outputs and
coax/fiber audio outputs, but the DVD player
provides neither cables nor the equipment
to use those extra *optional* ports.
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