RS-232 communication limitations
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Posts: 46,084
Hello all,
I have been reading a lot about the DB9 RS-232 connection between
the BASIC stamp 2 and a PC, and am rather confused. I plan to connect
my BS2sx to my computer via the 'serial' RS-232 port, for both
programming and communicating. With the existing hardware, that is
the RS-232 connection to the stamp advised on the parallax website
and a normal DB9 cable, is it possible to transfer I/O to, say, a c++
program? Also, as a side note, since the stamp runs on 0V to 5V and
true RS-232 runs on +12V to -12V, will I need a voltage converter to
make the initial connection? I know some laptops have problems with
this, and I'm sure all motherboard manufacturers work differently on
this issue, but in general are modern motherboards able to
communicate on 0V to 5V? Thanks again.
Stefan Dorsett
I have been reading a lot about the DB9 RS-232 connection between
the BASIC stamp 2 and a PC, and am rather confused. I plan to connect
my BS2sx to my computer via the 'serial' RS-232 port, for both
programming and communicating. With the existing hardware, that is
the RS-232 connection to the stamp advised on the parallax website
and a normal DB9 cable, is it possible to transfer I/O to, say, a c++
program? Also, as a side note, since the stamp runs on 0V to 5V and
true RS-232 runs on +12V to -12V, will I need a voltage converter to
make the initial connection? I know some laptops have problems with
this, and I'm sure all motherboard manufacturers work differently on
this issue, but in general are modern motherboards able to
communicate on 0V to 5V? Thanks again.
Stefan Dorsett
Comments
RS232 comm with a stamp for programming or just data IO is not
a problem at all - I am doing it everyday (using Linux btw).
Usually you dont need a voltage converter as todays interfaces are
well satisfied with TTL levels (btw RS232 levels are high -3..-12V
and low +3..+12V resp). You need Rx, Tx, DTR and GND from the
serial port to hook up a stamp. DTR is needed to reset the stamp for
programming and is not needed for just data IO (provided you don't
intend to reset the stamp in such cases). ATN is merely the base
of an internal transistor connected to /RST (ATN is positive logic
while /RST is negative logic).
Tx
SIN
Rx
SOUT
DTR
ATN
GND
Vss
or better (better noise resistance)
Tx
SIN
Rx
SOUT
DTR
+--||----ATN
_|_ 100n
---
|100n
GND
+
Vss
The problems which some laptops have ususally could be solved
by turning of the FIFO (I don't know why, but I never heared
of this being a problem with desktops).
Regards
Adrian
levels".
Have a look...
http://www.qsl.net/kf4haz/cables/stamps/
From: "Stefan Dorsett"
> Hello all,
> I have been reading a lot about the DB9 RS-232 connection between
> the BASIC stamp 2 and a PC, and am rather confused. I plan to connect
> my BS2sx to my computer via the 'serial' RS-232 port, for both
> programming and communicating. With the existing hardware, that is
> the RS-232 connection to the stamp advised on the parallax website
> and a normal DB9 cable, is it possible to transfer I/O to, say, a c++
> program? Also, as a side note, since the stamp runs on 0V to 5V and
> true RS-232 runs on +12V to -12V, will I need a voltage converter to
> make the initial connection? I know some laptops have problems with
> this, and I'm sure all motherboard manufacturers work differently on
> this issue, but in general are modern motherboards able to
> communicate on 0V to 5V? Thanks again.
> Stefan Dorsett
I read the documentation today when I was getting my 100nf
capacitors, so hopefully I'll be able to get everything hooked up and
working. If I have any more questions, expect me back here. Thanks
again.
Stefan
--- In basicstamps@yahoogroups.com, "Adrian Schneider"
<adrian.schneider@t...> wrote:
> Hi
>
> RS232 comm with a stamp for programming or just data IO is not
> a problem at all - I am doing it everyday (using Linux btw).
> Usually you dont need a voltage converter as todays interfaces are
> well satisfied with TTL levels (btw RS232 levels are high -3..-12V
> and low +3..+12V resp). You need Rx, Tx, DTR and GND from the
> serial port to hook up a stamp. DTR is needed to reset the stamp
for
> programming and is not needed for just data IO (provided you don't
> intend to reset the stamp in such cases). ATN is merely the base
> of an internal transistor connected to /RST (ATN is positive logic
> while /RST is negative logic).
>
> Tx
SIN
> Rx
SOUT
> DTR
ATN
> GND
Vss
>
> or better (better noise resistance)
>
> Tx
SIN
> Rx
SOUT
> DTR
+--||----ATN
> _|_ 100n
> ---
> |100n
> GND
+
Vss
>
> The problems which some laptops have ususally could be solved
> by turning of the FIFO (I don't know why, but I never heared
> of this being a problem with desktops).
>
> Regards
> Adrian
I got everything and hooked it up, and the stamp 2.0 beta couldn't
find it on either loopback or echo. I thought maybe the cable I was
using may be null modem, so I switched the send and recieve, still
nothing. I've tried using 100nf capacitors as advised, and connecting
straight through. I've tried even turning off FIFO on my desktop. I'm
powering the stamp through a 9V battery connected to VIN and VSS.
Please let me know if you see some sort of problem with my setup, or
if you have any suggestions. Thanks.
Stefan
--- In basicstamps@yahoogroups.com, "Stefan Dorsett"
<tebukuro42@y...> wrote:
> Thanks!
> I read the documentation today when I was getting my 100nf
> capacitors, so hopefully I'll be able to get everything hooked up
and
> working. If I have any more questions, expect me back here. Thanks
> again.
> Stefan
>
> --- In basicstamps@yahoogroups.com, "Adrian Schneider"
> <adrian.schneider@t...> wrote:
> > Hi
> >
> > RS232 comm with a stamp for programming or just data IO is not
> > a problem at all - I am doing it everyday (using Linux btw).
> > Usually you dont need a voltage converter as todays interfaces are
> > well satisfied with TTL levels (btw RS232 levels are high -3..-12V
> > and low +3..+12V resp). You need Rx, Tx, DTR and GND from the
> > serial port to hook up a stamp. DTR is needed to reset the stamp
> for
> > programming and is not needed for just data IO (provided you don't
> > intend to reset the stamp in such cases). ATN is merely the base
> > of an internal transistor connected to /RST (ATN is positive logic
> > while /RST is negative logic).
> >
> > Tx
SIN
> > Rx
SOUT
> > DTR
ATN
> > GND
Vss
> >
> > or better (better noise resistance)
> >
> > Tx
SIN
> > Rx
SOUT
> > DTR
+--||----ATN
> > _|_ 100n
> > ---
> > |100n
> > GND
+
Vss
> >
> > The problems which some laptops have ususally could be solved
> > by turning of the FIFO (I don't know why, but I never heared
> > of this being a problem with desktops).
> >
> > Regards
> > Adrian
be on the wrong pin, so you'll have to swap that
too (with the original DSR line).
So:
Straight through: 3 is TX-Out of PC, TX-In of BS2
2 is RX-In of PC, RX-Out of BS2
4 is DTR-OUT of PC, ATN-IN of BS2
Pin 5 is GROUND, common to both.
With NullModem cable:
Must swap 2 and 3, 6 and 4
--- In basicstamps@yahoogroups.com, "Stefan Dorsett"
<tebukuro42@y...> wrote:
> Ok, so I'm back.
> I got everything and hooked it up, and the stamp 2.0 beta couldn't
> find it on either loopback or echo. I thought maybe the cable I was
> using may be null modem, so I switched the send and recieve, still
> nothing. I've tried using 100nf capacitors as advised, and
connecting
> straight through. I've tried even turning off FIFO on my desktop.
I'm
> powering the stamp through a 9V battery connected to VIN and VSS.
> Please let me know if you see some sort of problem with my setup,
or
> if you have any suggestions. Thanks.
> Stefan
>
> --- In basicstamps@yahoogroups.com, "Stefan Dorsett"
> <tebukuro42@y...> wrote:
> > Thanks!
> > I read the documentation today when I was getting my 100nf
> > capacitors, so hopefully I'll be able to get everything hooked up
> and
> > working. If I have any more questions, expect me back here.
Thanks
> > again.
> > Stefan
> >
> > --- In basicstamps@yahoogroups.com, "Adrian Schneider"
> > <adrian.schneider@t...> wrote:
> > > Hi
> > >
> > > RS232 comm with a stamp for programming or just data IO is not
> > > a problem at all - I am doing it everyday (using Linux btw).
> > > Usually you dont need a voltage converter as todays interfaces
are
> > > well satisfied with TTL levels (btw RS232 levels are high -3..-
12V
> > > and low +3..+12V resp). You need Rx, Tx, DTR and GND from the
> > > serial port to hook up a stamp. DTR is needed to reset the
stamp
> > for
> > > programming and is not needed for just data IO (provided you
don't
> > > intend to reset the stamp in such cases). ATN is merely the base
> > > of an internal transistor connected to /RST (ATN is positive
logic
> > > while /RST is negative logic).
> > >
> > > Tx
SIN
> > > Rx
SOUT
> > > DTR
ATN
> > > GND
Vss
> > >
> > > or better (better noise resistance)
> > >
> > > Tx
SIN
> > > Rx
SOUT
> > > DTR
+--||----ATN
> > > _|_ 100n
> > > ---
> > > |100n
> > > GND
+
Vss
> > >
> > > The problems which some laptops have ususally could be solved
> > > by turning of the FIFO (I don't know why, but I never heared
> > > of this being a problem with desktops).
> > >
> > > Regards
> > > Adrian
on the connector, so it 'knows' it has a cable
connected. Sheesh.
--- In basicstamps@yahoogroups.com, "Allan Lane" <allan.lane@h...>
wrote:
> Well, if it IS null modem, the DTR/ATN line will
> be on the wrong pin, so you'll have to swap that
> too (with the original DSR line).
> So:
> Straight through: 3 is TX-Out of PC, TX-In of BS2
> 2 is RX-In of PC, RX-Out of BS2
> 4 is DTR-OUT of PC, ATN-IN of BS2
> Pin 5 is GROUND, common to both.
>
> With NullModem cable:
> Must swap 2 and 3, 6 and 4
>
> --- In basicstamps@yahoogroups.com, "Stefan Dorsett"
> <tebukuro42@y...> wrote:
> > Ok, so I'm back.
> > I got everything and hooked it up, and the stamp 2.0 beta
couldn't
> > find it on either loopback or echo. I thought maybe the cable I
was
> > using may be null modem, so I switched the send and recieve,
still
> > nothing. I've tried using 100nf capacitors as advised, and
> connecting
> > straight through. I've tried even turning off FIFO on my desktop.
> I'm
> > powering the stamp through a 9V battery connected to VIN and VSS.
> > Please let me know if you see some sort of problem with my setup,
> or
> > if you have any suggestions. Thanks.
> > Stefan
> >
> > --- In basicstamps@yahoogroups.com, "Stefan Dorsett"
> > <tebukuro42@y...> wrote:
> > > Thanks!
> > > I read the documentation today when I was getting my 100nf
> > > capacitors, so hopefully I'll be able to get everything hooked
up
> > and
> > > working. If I have any more questions, expect me back here.
> Thanks
> > > again.
> > > Stefan
> > >
> > > --- In basicstamps@yahoogroups.com, "Adrian Schneider"
> > > <adrian.schneider@t...> wrote:
> > > > Hi
> > > >
> > > > RS232 comm with a stamp for programming or just data IO is not
> > > > a problem at all - I am doing it everyday (using Linux btw).
> > > > Usually you dont need a voltage converter as todays
interfaces
> are
> > > > well satisfied with TTL levels (btw RS232 levels are high -
3..-
> 12V
> > > > and low +3..+12V resp). You need Rx, Tx, DTR and GND from the
> > > > serial port to hook up a stamp. DTR is needed to reset the
> stamp
> > > for
> > > > programming and is not needed for just data IO (provided you
> don't
> > > > intend to reset the stamp in such cases). ATN is merely the
base
> > > > of an internal transistor connected to /RST (ATN is positive
> logic
> > > > while /RST is negative logic).
> > > >
> > > > Tx
SIN
> > > > Rx
SOUT
> > > > DTR
ATN
> > > > GND
Vss
> > > >
> > > > or better (better noise resistance)
> > > >
> > > > Tx
SIN
> > > > Rx
SOUT
> > > > DTR
+--||----ATN
> > > > _|_ 100n
> > > > ---
> > > > |100n
> > > > GND
+
Vss
> > > >
> > > > The problems which some laptops have ususally could be solved
> > > > by turning of the FIFO (I don't know why, but I never heared
> > > > of this being a problem with desktops).
> > > >
> > > > Regards
> > > > Adrian
the ANT/DTR line. Use the jumper for Stamp download and debug. Open the
jumper for normal serial comm. Out of that connector.
Original Message
From: Adrian Schneider [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=0PqtCal0RStV_xCTvBMXgPKglueXybx24e3GZWurSVpnWEnM-swnK8IfsCpe23dWtAm-vHgvxcALhqS2cVqeygZZJHMDFQ]adrian.schneider@t...[/url
Sent: Wednesday, May 14, 2003 3:36 AM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Re: RS-232 communication limitations
Hi
RS232 comm with a stamp for programming or just data IO is not
a problem at all - I am doing it everyday (using Linux btw).
Usually you dont need a voltage converter as todays interfaces are
well satisfied with TTL levels (btw RS232 levels are high -3..-12V
and low +3..+12V resp). You need Rx, Tx, DTR and GND from the
serial port to hook up a stamp. DTR is needed to reset the stamp for
programming and is not needed for just data IO (provided you don't
intend to reset the stamp in such cases). ATN is merely the base
of an internal transistor connected to /RST (ATN is positive logic
while /RST is negative logic).
Tx
SIN
Rx
SOUT
DTR
ATN
GND
Vss
or better (better noise resistance)
Tx
SIN
Rx
SOUT
DTR
+--||----ATN
_|_ 100n
---
|100n
GND
+
Vss
The problems which some laptops have ususally could be solved
by turning of the FIFO (I don't know why, but I never heared
of this being a problem with desktops).
Regards
Adrian
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