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'[EE] Help on cable selection'
2005\02\23@145839 by Padu

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Hi,

I need to connect the device I'm developing to a PC using a serial port. Right now, on my development board I have a PCB DB9 female, that makes the PC connection using a standard DB9 male - DB9 female 1-to-1 cable.

The thing is my device is too small to have a PCB DB9 female, so I was thinking of other types of connection. I'm only using the Rx and Tx lines (do I need to have a cable with more than 2 wires?) so I was thinking of a smaller connector in the device (RJ11 for example) and providing a RJ11 male to DB9 female cable with my device, but I couldn't find such cable on mouser. Is this so out of the normal that I'll have to customize a cable for this application or do you know a manufacturer that makes such a cable (or one that uses similar small sized connector on one side of the cable)

TIA

Padu

2005\02\23@150625 by Bob Blick

face picon face
Padu writes:

> I'm only using the Rx and Tx lines
> (do I need to have a cable with more than 2 wires?)

You'll need ground as well.

> smaller connector in the device (RJ11 for example) and providing a RJ11
> male to DB9 female cable with my device, but I couldn't find such cable on
> mouser.

You can get shells that have DB9 on one end and RJ11 female on the other.

Cheers,

Bob


2005\02\23@152055 by Herbert Graf

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face
On Wed, 2005-02-23 at 11:56 -0800, Padu wrote:
> Hi,
>
> I need to connect the device I'm developing to a PC using a serial port. Right now, on my development board I have a PCB DB9 female, that makes the PC connection using a standard DB9 male - DB9 female 1-to-1 cable.
>
> The thing is my device is too small to have a PCB DB9 female, so I was thinking of other types of connection. I'm only using the Rx and Tx lines (do I need to have a cable with more than 2 wires?) so I was thinking of a smaller connector in the device (RJ11 for example) and providing a RJ11 male to DB9 female cable with my device, but I couldn't find such cable on mouser. Is this so out of the normal that I'll have to customize a cable for this application or do you know a manufacturer that makes such a cable (or one that uses similar small sized connector on one side of the cable)

There was an earlier thread on something similar to this.

Beyond what is available there is something else you need to consider
when using other connectors: what will people do?

For example: if you use an RJ11 connector you have to be prepared for
people to plug your device into a phone line (can your device handle 100
+ volts AC?)

Other connectors have similar problems. I'm not saying NOT to consider
other connectors, only to consider how "inventive" people will be with
what you plug your product into.

TTYL

-----------------------------
Herbert's PIC Stuff:
http://repatch.dyndns.org:8383/pic_stuff/

2005\02\23@154108 by redtock8

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Hi Padu,
I do this all the time. I use a DB9 to RJ45
adapter and a CAT5 patch cable. You need RX,TX,GND.
I buy the adapter at Frys for a couple of bucks
Fry's pn: 2402340, it's made by Pan Pacific.
Albert
=================================
DXTron Technology Inc
Atlanta, Ga
PCB Assembly
TH and SMT
PCB Design
PIC Chip Programming
Systems Design and Programming
=================================
spam_OUTredrock8TakeThisOuTspamdxtron.com
http://www.dxtron.com
=================================
{Original Message removed}

2005\02\23@155729 by Padu

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From: "Herbert Graf"
> For example: if you use an RJ11 connector you have to be prepared for
> people to plug your device into a phone line (can your device handle 100
> + volts AC?)

What I like about the RJ11 idea is:
1) small size
2) cable easily available (if not a direct one, then a standard serial cable
with an RJ11-DB9 adapter
What I don't like about the RJ11 for my application is:
1) Agreeing with you, the capability of plugging the device to non-intended
sources, and no, I guess my device would explode if plugged to 100v ac :-)
2) Not too small size for my enjoyment
3) Somehow I don't think RJ11 has a "snug" fit. I think it is fragile and it
will break with time, but that's only my impression.

The device is a GPS receiver and I want to provide a PC communication link.
One idea would be using what is already on the market, for example the
Garmin eSeries cable, but I cannot find the female connector to include into
my device.

I have a voice recorder in my hands right now. It connects to the PC using a
USB connection instead serial cable. On one end of the cable, there is a
regular USB male connector, but on the other end, there is a very small
(USB?) connector. That connector size would be perfect for my application.
Can I use a USB miniature connector (4 pins?) in a custom cable to carry
serial data? Is that a good idea?

Another idea would be using another type of small connector (DIN-8?) and
provide a custom cable, but I still don't know what are the costs involved
with custom cables.

2005\02\23@170421 by John J. McDonough

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----- Original Message -----
From: "Bob Blick" <.....bblickKILLspamspam@spam@sonic.net>
Subject: Re: [EE] Help on cable selection


> You can get shells that have DB9 on one end and RJ11 female on the other.

DEC (the now-defunct Digital Equipment Corp) used to have such a thing ...
well, almost.  They had an RJ11-like connector and DB9, or maybe it was DB25
...it was a while back, shell with an RJ type jack.  They had the tab offset
so it wasn't an honest RJ11, probably to avoid Herbert's problem.  The tab
prevented it from going into a phone jack.

How about a mouse connector?  That is essentially a serial connector anyway.

--McD


2005\02\23@173856 by Robert Rolf

picon face
You could also use a 3.5 mm stereo headphone plug/jack.
You'd have to make your own adapter, but we've been using them
for years on our experimental stimulators, with good success.
Put PC Tx on ring so you'll never get tx-tx collision when
inserting.

redtock8@dxtron wrote:

{Quote hidden}

> {Original Message removed}

2005\02\23@175250 by Mike Hord

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> I have a voice recorder in my hands right now. It connects to the PC using a
> USB connection instead serial cable. On one end of the cable, there is a
> regular USB male connector, but on the other end, there is a very small
> (USB?) connector. That connector size would be perfect for my application.
> Can I use a USB miniature connector (4 pins?) in a custom cable to carry
> serial data? Is that a good idea?

Not the worst; if your device can handle serial port levels, it can surely
handle USB signal levels.

Of course, now you've given your users a device that will let them plug their
USB-based MP3 player/digital camera/whatever into a serial port.  But that's
their problem.  ;-)

Mike H.

2005\02\23@175833 by Jinx

face picon face
> I'm only using the Rx and Tx lines (do I need to have a cable with
> more than 2 wires?)

Adding ground would be good. You could use a small stereo jack
if you wanted

> Other connectors have similar problems. I'm not saying NOT to
> consider other connectors, only to consider how "inventive" people
> will be with what you plug your product into.

I have this internal dialogue a lot. "What if someone ....." Well, I
reckon if you label it clearly and permanently, they ignore that label
at their peril. There has to be some sort of responsibility on the user

2005\02\23@180448 by Padu

picon face
From: "John J. McDonough"
> How about a mouse connector?  That is essentially a serial connector
anyway.
>
> --McD


That's not a bad idea, but it also brings the custom cable issue. Os is
there a PS/2 to DB9 cable? I like the size of the PS/2 and I believe PCB
connectors should be really easy to find.

2005\02\23@185005 by Russell McMahon

face
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> That's not a bad idea, but it also brings the custom cable issue. Os
> is
> there a PS/2 to DB9 cable? I like the size of the PS/2 and I believe
> PCB
> connectors should be really easy to find.

A PS2 connector is arguably a bit delicate for non expert users, or
when used often. Alignment is not obvious to the uninitiated and
connector damage is possible.


       RM

2005\02\23@201850 by Robert Rolf

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Jinx wrote:

>>I'm only using the Rx and Tx lines (do I need to have a cable with
>>more than 2 wires?)
>
>
> Adding ground would be good. You could use a small stereo jack
> if you wanted
>
>
>>Other connectors have similar problems. I'm not saying NOT to
>>consider other connectors, only to consider how "inventive" people
>>will be with what you plug your product into.
>
>
> I have this internal dialogue a lot. "What if someone ....." Well, I
> reckon if you label it clearly and permanently, they ignore that label
> at their peril. There has to be some sort of responsibility on the user

It's also not that hard to choose wisely.
Gnd is gnd, Rx is one of the data lines, and Tx is USB 5V so
that a misconnected cable will at best just barely power the USB
device.

Robert
It's hard to make things foolproof because fools are so ingenious.


2005\02\23@203801 by Mark Rages

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On Wed, 23 Feb 2005 15:39:00 -0700, Robert Rolf <.....Robert.RolfKILLspamspam.....ualberta.ca> wrote:
> You could also use a 3.5 mm stereo headphone plug/jack.
> You'd have to make your own adapter, but we've been using them
> for years on our experimental stimulators, with good success.
> Put PC Tx on ring so you'll never get tx-tx collision when
> inserting.
>

My old digital camera came with this type of cable.  You might be able
to find a bunch on the surplus market for very cheap.

Otherwise, use an 8-pin mini-din in the pinout used by old Macs and
some video equipment. (sony dxc-950 at least). MCM electronics sells a
DB-9 to minidin-8 cable for this one.

Regards,
Mark
markrages@gmail
--
You think that it is a secret, but it never has been one.
 - fortune cookie

2005\02\23@205247 by Jinx

face picon face
> > at their peril. There has to be some sort of responsibility on the user
>
> It's also not that hard to choose wisely.
> Gnd is gnd, Rx is one of the data lines, and Tx is USB 5V so
> that a misconnected cable will at best just barely power the USB
> device.
>
> Robert
> It's hard to make things foolproof because fools are so ingenious.

Not EE, but highlights the issue of user responsibility - from today's
local paper, man dies after accidentally drinking a glass of caustic

http://www.nzherald.co.nz/index.cfm?c_id=1&ObjectID=10112417

I'm not saying the man was a fool. Perhaps foolish, certainly unwise,
given that he knew he had impairments. Apparently the victim of his
own misadventure, which some might call rough justice. A serviceman
friend of mine told me once he did a call-out to a place and found
battery equipment that had 3-pin mains plugs for high-amp12V
connections. No wonder the Darwin Awards and Fire Brigade keep
going

2005\02\23@233424 by Dwayne Reid

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At 01:55 PM 2/23/2005, Padu wrote:
>From: "Herbert Graf"
> > For example: if you use an RJ11 connector you have to be prepared for
> > people to plug your device into a phone line (can your device handle 100
> > + volts AC?)
>
>What I like about the RJ11 idea is:
>1) small size
>2) cable easily available (if not a direct one, then a standard serial cable
>with an RJ11-DB9 adapter
>What I don't like about the RJ11 for my application is:
>1) Agreeing with you, the capability of plugging the device to non-intended
>sources, and no, I guess my device would explode if plugged to 100v ac :-)
>2) Not too small size for my enjoyment
>3) Somehow I don't think RJ11 has a "snug" fit. I think it is fragile and it
>will break with time, but that's only my impression.

I've seen a RJ11 used this way before and at least one version seemed OK:
both inner conductors were ground, the outer conductors were TX & RX.

I saw another version that used a RJ-12 (6 pins): pins 1 & 6 were TX, pins
2 & 5 were RX, pins 3 & 4 were ground.

Finally, my Brady label maker (TLS2200) uses a RJ-22 (4 pin handset
connector) with both outside pins ground, the inner pins were TX & RX.  The
smaller connector size made it impossible to plug in a regular RJ-11 or
RJ-12 telco cord.

dwayne

--
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2005\02\24@085530 by ?J=2E_Pe=F1a?=

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> The thing is my device is too small to have a PCB DB9 female, so I was
> thinking of other types of connection. I'm only using the Rx and Tx lines
> (do I need to have a cable with more than 2 wires?) so I was thinking of
> a smaller connector in the device (RJ11 for example) and providing a RJ11
> male to DB9 female cable with my device, but I couldn't find such cable
> on mouser. Is this so out of the normal that I'll have to customize a
> cable for this application or do you know a manufacturer that makes such
> a cable (or one that uses similar small sized connector on one side of
> the cable)

Many networking/telecom products use an RJ45 as serial connector. So you
use a standard UTP patch and an adapter like:

http://www.pccables.com/01910.htm

Saludos,
                                       HoraPe
---
Horacio J. Peña
horapespamspam_OUTcompendium.com.ar
@spam@horapeKILLspamspamuninet.edu

2005\02\24@111434 by Support - KF4HAZ

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www.qsl.net/kf4haz/cables/stamps/
This is the solution I use for the "Basic Stamp".
You will need a minimum of 3 conductors, RX TX and Gnd.

----- From: "Padu" <padu@
Hi,

I need to connect the device I'm developing to a PC using a serial port. Right now, on my development board I have a PCB DB9 female, that makes the PC connection using a standard DB9 male - DB9 female 1-to-1 cable.

The thing is my device is too small to have a PCB DB9 female, so I was thinking of other types of connection. I'm only using the Rx and Tx lines (do I need to have a cable with more than 2 wires?) so I was thinking of a smaller connector in the device (RJ11 for example) and providing a RJ11 male to DB9 female cable with my device, but I couldn't find such cable on mouser. Is this so out of the normal that I'll have to customize a cable for this application or do you know a manufacturer that makes such a cable (or one that uses similar small sized connector on one side of the cable)

TIA

Padu

2005\02\24@192753 by Bob Ammerman

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You will need a minimum of 3 conductors: TX, RX and Ground.

Bob Ammerman
RAm Systems

2005\02\24@200957 by Padu

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From: "Bob Ammerman"

> You will need a minimum of 3 conductors: TX, RX and Ground.
>
> Bob Ammerman



That's correct, and we've decided on using a mini firewire to db9 cable. I
didn't know that, but the cable company we make other types of cable here
will manufacture for less than 5 bucks (on a 500 batch).



2005\02\25@154847 by Peter L. Peres

picon face


> That's correct, and we've decided on using a mini firewire to db9 cable. I
> didn't know that, but the cable company we make other types of cable here
> will manufacture for less than 5 bucks (on a 500 batch).

I hope you mark your cables clearly.

Peter

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