SEROUT cable problem?
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Posts: 46,084
Dear friend,
I had some experience, know how to run Stamps II, my current urgent
matter
is to send some ASCII strings to control machine (which accepts ASCII
command, this has been verified by using DOS kermit program
to send character at fixed 19200 N,8,1, mode, or Hyperterm works too)
Now, I have tried to program and sedn ascii code out from the same
RS232 port on the StampII super carrier board, it does not work.
Could you please enlighten what modification I need if I just need stamp
stand alone and send our ASCII strings to machine and one time, done.
I though the machine I want to control will supply negative voltage
to StampII? becaue it hs builtin RS232 jack. Do I need to supply
-12V to StampII board?
When I use DOS kermit.exe program to talk to the machine, I need to use
stright (pin2-pin2, pin3-pin3) null modem cable though (just like the
one
PC to StampII carrier board is hooked up)
thanks,pe
I had some experience, know how to run Stamps II, my current urgent
matter
is to send some ASCII strings to control machine (which accepts ASCII
command, this has been verified by using DOS kermit program
to send character at fixed 19200 N,8,1, mode, or Hyperterm works too)
Now, I have tried to program and sedn ascii code out from the same
RS232 port on the StampII super carrier board, it does not work.
Could you please enlighten what modification I need if I just need stamp
stand alone and send our ASCII strings to machine and one time, done.
I though the machine I want to control will supply negative voltage
to StampII? becaue it hs builtin RS232 jack. Do I need to supply
-12V to StampII board?
When I use DOS kermit.exe program to talk to the machine, I need to use
stright (pin2-pin2, pin3-pin3) null modem cable though (just like the
one
PC to StampII carrier board is hooked up)
thanks,pe
Comments
1) The ATN line (pin 3 of the Stamp) needs to be disconnected.
2) It seems like I have had spotty trouble getting the built-in port to run
over 9600 baud. This may be a limitation of the way the port works to get
the - voltage. Long cables might contribute to this.
3) Is it possible the machine doesn't supply -12V?
The ATN line resets the Stamp during programming. Disconnect it while trying
to use the serial port. If you don't want to modify the board, try modifying
the cable or making a small adapter that you can plug in and remove.
The way the port works is it swings the -12V from the external device's
transmitter and routes it back to the Stamp's transmitter. So the swing
is -12V to 5V. This has three ramifcations. First, if the device doesn't
have a transmitter then there may be no -12V available. Second, anything the
device sends to the Stamp gets sent back to the sender (echo). Third, only
half duplex communications are possible.
Personally, I'd use a MAX232 connected to another pin. This chip uses
capacitors to generate +/- supplies from a single 5V supply (not quite
+/-12V in all cases, but within spec).
Regards,
Al Williams
AWC
* Read 8 channels of pulse input with the new PAK-VII.
http://www.al-williams.com/awce/pak7.htm
>
Original Message
> From: pwang@d... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=m1bgyVJrE32dVNCYjyt8-tHfT_IxSURWHHoM3gSG4kGKu3O8Wa49TQE4LcFQbPXo2gdU6SF3RG2ViU2bE885]pwang@d...[/url
> Sent: Tuesday, March 14, 2000 9:22 AM
> To: basicstamps@eGroups.com
> Subject: [noparse][[/noparse]basicstamps] SEROUT cable problem?
>
>
> Dear friend,
> I had some experience, know how to run Stamps II, my current urgent
> matter
> is to send some ASCII strings to control machine (which accepts ASCII
> command, this has been verified by using DOS kermit program
> to send character at fixed 19200 N,8,1, mode, or Hyperterm works too)
>
> Now, I have tried to program and sedn ascii code out from the same
> RS232 port on the StampII super carrier board, it does not work.
> Could you please enlighten what modification I need if I just need stamp
> stand alone and send our ASCII strings to machine and one time, done.
> I though the machine I want to control will supply negative voltage
> to StampII? becaue it hs builtin RS232 jack. Do I need to supply
> -12V to StampII board?
>
> When I use DOS kermit.exe program to talk to the machine, I need to use
> stright (pin2-pin2, pin3-pin3) null modem cable though (just like the
> one
> PC to StampII carrier board is hooked up)
> thanks,pe
>
>
>
> eGroups.com Home: http://www.egroups.com/group/basicstamps/
> http://www.egroups.com - Simplifying group communications
>
Thank you very much for your reply.
> 1) The ATN line (pin 3 of the Stamp) needs to be disconnected.
I used voltage meter to check continuity, the pin3 of StampII, does
not connect to super carrier board RS232 jack pin4 (why? Just out of the
box, should they be connected, anyway I can download program to Stamp
from PC)
> 2) It seems like I have had spotty trouble getting the built-in port
to run
> over 9600 baud. This may be a limitation of the way the port works to
get
> the - voltage. Long cables might contribute to this.
I thought it will work at 19200 that's why I bought it.
> 3) Is it possible the machine doesn't supply -12V?
I'll ahve to check.
`
> The ATN line resets the Stamp during programming. Disconnect it while
trying
> to use the serial port. If you don't want to modify the board, try
modifying
> the cable or making a small adapter that you can plug in and remove.
>
> The way the port works is it swings the -12V from the external
device's
> transmitter and routes it back to the Stamp's transmitter. So the
swing
> is -12V to 5V. This has three ramifcations. First, if the device
doesn't
> have a transmitter then there may be no -12V available. Second,
anything the
> device sends to the Stamp gets sent back to the sender (echo). Third,
only
> half duplex communications are possible.
Yes, I am going to stand-alone send ASCII text out of Stamp, so it is
one way.
>
> Personally, I'd use a MAX232 connected to another pin. This chip uses
> capacitors to generate +/- supplies from a single 5V supply (not quite
> +/-12V in all cases, but within spec).
Great, this seems a good way, but which pin on Stamp?
Same SEROUT command?
athanks,pe
> Regards,
>
> Al Williams
> AWC
> * Read 8 channels of pulse input with the new PAK-VII.
> http://www.al-williams.com/awce/pak7.htm
>
>
>
> >
Original Message
> > From: pwang@d... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=MoQwc_YK7R0m3V2YJtZGbFaCsPV1QALXTYWusRHy-1mOAauhtRzv8vab0Sw4gTJettfcOLre4L8R3A]pwang@d...[/url
> > Sent: Tuesday, March 14, 2000 9:22 AM
> > To: basicstamps@eGroups.com
> > Subject: [noparse][[/noparse]basicstamps] SEROUT cable problem?
> >
> >
> > Dear friend,
> > I had some experience, know how to run Stamps II, my current urgent
> > matter
> > is to send some ASCII strings to control machine (which accepts
ASCII
> > command, this has been verified by using DOS kermit program
> > to send character at fixed 19200 N,8,1, mode, or Hyperterm works
too)
> >
> > Now, I have tried to program and sedn ascii code out from the same
> > RS232 port on the StampII super carrier board, it does not work.
> > Could you please enlighten what modification I need if I just need
stamp
> > stand alone and send our ASCII strings to machine and one time,
done.
> > I though the machine I want to control will supply negative voltage
> > to StampII? becaue it hs builtin RS232 jack. Do I need to supply
> > -12V to StampII board?
> >
> > When I use DOS kermit.exe program to talk to the machine, I need to
use
> > stright (pin2-pin2, pin3-pin3) null modem cable though (just like
the
> > one
> > PC to StampII carrier board is hooked up)
> > thanks,pe
> >
> >
> box, should they be connected, anyway I can download program to Stamp
> from PC)
The carrier board probably connects ATN through a capacitor. If that is
true, then you should be OK on this count. The capacitor (which looks open
at DC) prevents the line from holding the Stamp in reset, but does allow the
programming software to pulse the reset pin.
>
> > 2) It seems like I have had spotty trouble getting the built-in port
> to run
> > over 9600 baud. This may be a limitation of the way the port works to
> get
> > the - voltage. Long cables might contribute to this.
> I thought it will work at 19200 that's why I bought it.
The Stamp supports 19200, but if memory serves, I have had spotty trouble
running port 16 over 9600 baud. As a guess, the capacitance of a long cable
might cause problems because of the -12V scheme.
>
> > 3) Is it possible the machine doesn't supply -12V?
> I'll ahve to check.
If the machine only receives, it is possible that it doesn't provide a
transmitter and if that were true, you'd have a problem.
> Yes, I am going to stand-alone send ASCII text out of Stamp, so it is
> one way.
Well, that is from your point of view. But, for example, suppose the device
echos characters back or sends some other information back. This could cause
your transmission to drop out as it loses its source of -12V.
> >
> > Personally, I'd use a MAX232 connected to another pin. This chip uses
> > capacitors to generate +/- supplies from a single 5V supply (not quite
> > +/-12V in all cases, but within spec).
> Great, this seems a good way, but which pin on Stamp?
> Same SEROUT command?
Any pin you want. Just specify the pin # instead of 16 in SEROUT.
Regards,
Al Williams
AWC
*Floating point math for the Stamp, PIC, SX or any microcontroller at
http://www.al-williams.com/awce
> I need to use stright (pin2-pin2, pin3-pin3) null modem
> cable though (just like the
> onePC to StampII carrier board is hooked up)
That is a modem cable, not a null modem cable. You would in fact need a
null modem adapter (3-2,2-3) to talk between the stamp and the machine.
Can you communicate with the machine with _only_ pins 2,3,and 5 connected?
Maybe the machine requires a flow control pin as well. Test the voltage
levels on other pins too. Be sure you are using the non-inverted baud
mode for 19200 baud:
SEROUT 16,32,[noparse][[/noparse]stuff]
And be sure "stuff" is really the ASCII strings you want, by previewng them
to a debug window on the PC.
-- Tracy Allen
Electronically Monitored Ecosystems
http://www.emesystems.com
Yes, that will make a big difference!
In the old days we would say that the PC was DTE (Data Terminal Equipment).
That makes the carrier board DCE (Data Comm Equipment). If you are using a
straight cable to connect to the PC to the device it is also DCE.
DTE <-> DCE = Straight cable
DTE <-> DTE = Cross cable (Null modem)
DCE <-> DCE = Cross cable (Null modem)
The trick part is getting a cross cable that will also fool all the flow
control, etc. As Tracy mentioned, try hooking up 2,3,5 and no other pins on
the PC and see if you can still get it to talk. A breakout box is most
useful in this case. If it won't work, you can often wire the flow control
together. In otherwords, connect RTS and CTS or the same side just to fool
the device.
Sorry I missed that one.
Regards,
Al Williams
AWC
* Microcontroller Projects with Basic Stamps:
http://www.al-williams.com/awce/sbook.htm
>
Original Message
> From: Tracy Allen [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=EqNMY7TO0sTqqow-EhGcRqFvWd-F-1qU65KmqZkVsbk7bAwE2Me4QRr6Q3KxmDqmUF-cixtosh2z_aLx5A]emesys@c...[/url
> Sent: Tuesday, March 14, 2000 10:54 AM
> To: INTERNET:basicstamps@eGroups.com
> Subject: [noparse][[/noparse]basicstamps] SEROUT cable problem?
>
>
> > When I use DOS kermit.exe program to talk to the machine,
> > I need to use stright (pin2-pin2, pin3-pin3) null modem
> > cable though (just like the
> > onePC to StampII carrier board is hooked up)
>
> That is a modem cable, not a null modem cable. You would in fact need a
> null modem adapter (3-2,2-3) to talk between the stamp and the machine.
> Can you communicate with the machine with _only_ pins 2,3,and 5
> connected?
> Maybe the machine requires a flow control pin as well. Test the voltage
> levels on other pins too. Be sure you are using the non-inverted baud
> mode for 19200 baud:
> SEROUT 16,32,[noparse][[/noparse]stuff]
> And be sure "stuff" is really the ASCII strings you want, by
> previewng them
> to a debug window on the PC.
>
> -- Tracy Allen
> Electronically Monitored Ecosystems
> http://www.emesystems.com
>
>
>
>
>
>
> eGroups.com home: http://www.egroups.com/group/basicstamps
> http://www.egroups.com - Simplifying group communications
>
>
>