5V serial port

  • Thread starter Thread starter Russ Du Preez
  • Start date Start date
R

Russ Du Preez

Hi all,

I am using a scanner attached to my handheld. The handheld is a ce.net
4.2 device.

I can read from devices not needing 5V fine. How do I enable the 5V on
the device?

Thanks,
Russ
 
The only one that could possibly tell you how (and if) the port supports TTL
is the OEM. Ask them. It typically requires a physical change to the
board.
 
"the 5V on the device", huh? What makes you think that there's some sort of
5V on every serial port? Many devices allow for their power to be supplied
from 5V on the ring indicator (RI), pin of the serial port, but that's *not*
part of RS-232 or any other standard; it's a de facto way of doing it. How
you make that happen for a given device, it should be obvious, is going to
vary from device to device, as Chris said. If you need to work with all
RS-232 devices, you'll have to forget about powering from a pin on the
serial port. Your PC, for example, doesn't provide 5V.

Paul T.
 
Well, I think it's clear from Paul and Chris's replies that you need to be
more clear on the following issues:

1) What do you mean by 5V (e.g. Power supply rail on the RI pin or some
other pin? TTL level signals instead of the RS2-32 levels? Something else we
haven't considered? )

2) What specific device are you using? As the others have pointed out. There
is no standard for any of this so, if the device supports it at all, the
device vendor would have to document how to do it.
 
If your CE device does not provide 5V on the pin that your scanner needs,
you will have to furnish that voltage from an external power supply -- or
connection. Such powering is not standard (though RS-232 and "standard"
is/are a little oxymoronic), so it is up to you and your vendor to agree on
how this is done.

Just to add to what Chis, Paul and Steve have said.

Dick

--
Richard Grier, MVP
Hard & Software
Author of Visual Basic Programmer's Guide to Serial Communications, Fourth
Edition,
ISBN 1-890422-28-2 (391 pages, includes CD-ROM). July 2004, Revised March
2006.
See www.hardandsoftware.net for details and contact information.
 
Thanks Chris,

The OEM does supply an API that enables TTL on the port.
Thanks again!!

Russ
 
Hi All,

Thanks for all the comments.
You guys are right, many devices using RS232 are powered externally.
Using an external device that needs to be powered by a handheld is a
little "oxymoronic" ;)

Due to the fact that we are usually governed by buerocratic
organisations or rather sales teams that say we are the experts, and
can do all things for all men (without the controlling influence, that
they apparently have).
I am glad that atleast we have OEM's that are proactive for cases like
these.

I think that the OEM's that develop the external devices should come
back to earth and rethink their entire solution.

Thanks again.
Russ
 
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