Comments
RS232 DB25 to DB9 converter. The original pinout for RS232 was developed for a 25 pins sub D connector. Since the introduction of the smaller serial port on the IBM-AT, 9 pins RS232 connectors are commonly used. A 10Base-T Cross-over swaps TD and RD.That is, swap pins 1 and 3 as well as pins 2 and 6, on one end of the cable. AT&T 258A wiring is comparable to T568B.
- edited 2003-09-14 - 02:18:00Yea, It's call an OHM METER. Would that be CHINA STANDARD or KOREA STANDARD
or JAPAN STANDARD or CANADIAN STANDARD or USA STANDARD ?
Original MessageFrom: Christian Wentz [noparse][[/noparse]mailto:cwentz86@h...]
Sent: Saturday, September 13, 2003 7:19 PM
To: [email protected]
Subject: [noparse][[/noparse]basicstamps] serial cable color coding
Would anyone happen to know of a resource that lists the standard serial
cable color coding?
_________________________________________________________________
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Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ - edited 2003-09-14 - 02:27:00I don't think there is a standard, but an old tech who used to work for
me would do them (at least the first 10) in resistor color code, black,
brown, red, etc.
Al Williams
AWC
* Control 8 servos at once: http://www.al-williams.com/pak8.htm
>Original Message> From: Christian Wentz [noparse][[/noparse]mailto:cwentz86@h...]
> Sent: Saturday, September 13, 2003 6:19 PM
> To: [email protected]
> Subject: [noparse][[/noparse]basicstamps] serial cable color coding
>
>
> Would anyone happen to know of a resource that lists the
> standard serial
> cable color coding?
>
> _________________________________________________________________
> Send and receive larger attachments with Hotmail Extra Storage.
> http://join.msn.com/?PAGE=features/es
>
>
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> [email protected]
> from the same email address that you subscribed. Text in the
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>
> - edited 2003-09-14 - 02:28:00There is no general standard for wire color on PC cabling, with the
exception of marking pin 1 on ribbon cables, and the color of power
supply and fan wiring. Everything else is probably gonna be factory or
manufacturer specific.
What Jim is trying to say is that because everyone has a different color
code, you need to use an ohm meter or continuity tester to figure out
what color wire goes to which pin on the cable that you have.
> Yea, It's call an OHM METER. Would that be CHINA STANDARD or KOREA STANDARD
> or JAPAN STANDARD or CANADIAN STANDARD or USA STANDARD ?
> Would anyone happen to know of a resource that lists the standard serial
> cable color coding? - edited 2003-09-14 - 02:34:00It may depend on if they use the metric or US color code as well? <grin>
And don't get me started on the metric versus US electricity.
> I don't think there is a standard, but an old tech who used to work for
> me would do them (at least the first 10) in resistor color code, black,
> brown, red, etc.
> > Would anyone happen to know of a resource that lists the
> > standard serial
> > cable color coding? - edited 2003-09-14 - 04:15:00In a message dated 9/13/2003 6:27:55 PM Pacific Daylight Time,
alw@a... writes:
I don't think there is a standard, but an old tech who used to work for
me would do them (at least the first 10) in resistor color code, black,
brown, red, etc.
Al Williams
AWC
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
I do the same, and think it is a good idea. If you are consistent with this
method, at least one knows number 1 through 10
[noparse][[/noparse]Non-text portions of this message have been removed] - edited 2003-09-14 - 05:03:00I do not think the color coding of cables is arbitrarily.
If you look a telephoneman splicing hundreds of wires , they follow
a color code scheme.
Perhaps there is an ANSI standard (they have standards for almost
everythinng). - edited 2003-09-14 - 16:23:00If you are a telephone man, with a 50-pair telephone
cable, you'd better have a standard for what pair
of wires goes where. If you're installing a
50 foot 8-wire cable between a PC and a Modem, you have
a lot more lattitude.
If you are installing an 'RS-232' 'Standard' cable
(ansi standard RS-232, RS-232b, RS-232c) well:
You could install a DB25 with all pins connected,
all pins defined -- but I don't think they spec
the color.
You could install a DB25 with only the common 8
lines -- RX,TX, CTS,RTS, DCD,DTR,DTS, and Ground.
Oops, forgot 'RI' (ring) used by the PC as IRQ input.
Or you could do DB9. Or you could do RJ45 (like
DEC and Stallion did). Or you could do 'three-wire'
(TX, RX and Ground).
The point is: the RS-232 'Standard' came out so
early that it's evolved quite a lot, and been
used in MANY form factors. It's amazing
that it's as portable, and still works, as it is.
There IS a specification, but I really don't think
it calls out wire colors.
--- In [email protected], 'Albert Catano'
<acatano2002@y...> wrote:
> I do not think the color coding of cables is arbitrarily.
> If you look a telephoneman splicing hundreds of wires , they
follow
> a color code scheme.
> Perhaps there is an ANSI standard (they have standards for almost
> everythinng). - edited 2003-09-14 - 18:02:00Well I would think there would be a standard ! if nothing more than just pin
to color standard ! But I can't find anything. I have used wire color to pin
numbers, but can't find the chart, and it wasn't specific to rs232.
Larry Gaminde
Original MessageFrom: 'Bill Boyer' <daweasel@s...>
To: 'Basic Stamp List' <[email protected]>
Sent: September 13, 2003 6:28 PM
Subject: RE: [noparse][[/noparse]basicstamps] serial cable color coding
> There is no general standard for wire color on PC cabling, with the
> exception of marking pin 1 on ribbon cables, and the color of power
> supply and fan wiring. Everything else is probably gonna be factory or
> manufacturer specific.
>
> What Jim is trying to say is that because everyone has a different color
> code, you need to use an ohm meter or continuity tester to figure out
> what color wire goes to which pin on the cable that you have.
>
>
> > Yea, It's call an OHM METER. Would that be CHINA STANDARD or KOREA
STANDARD
> > or JAPAN STANDARD or CANADIAN STANDARD or USA STANDARD ?
>
> > Would anyone happen to know of a resource that lists the standard serial
> > cable color coding?
>
>
>
> To UNSUBSCRIBE, just send mail to:
> [email protected]
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
> - edited 2003-09-15 - 02:00:00Now I lay me down to sleep
With a roll of cable at my feet
If I should die before I wake
White, Blue, Orange, Green, Brown, Slate.
Original MessageFrom: 'Allan Lane' <allan.lane@h...>
To: <[email protected]>
Sent: Sunday, September 14, 2003 8:23 AM
Subject: [noparse][[/noparse]basicstamps] Re: serial cable color coding
> If you are a telephone man, with a 50-pair telephone
> cable, you'd better have a standard for what pair
> of wires goes where. If you're installing a
> 50 foot 8-wire cable between a PC and a Modem, you have
> a lot more lattitude.
>
> If you are installing an 'RS-232' 'Standard' cable
> (ansi standard RS-232, RS-232b, RS-232c) well:
> You could install a DB25 with all pins connected,
> all pins defined -- but I don't think they spec
> the color.
>
> You could install a DB25 with only the common 8
> lines -- RX,TX, CTS,RTS, DCD,DTR,DTS, and Ground.
> Oops, forgot 'RI' (ring) used by the PC as IRQ input.
>
> Or you could do DB9. Or you could do RJ45 (like
> DEC and Stallion did). Or you could do 'three-wire'
> (TX, RX and Ground).
>
> The point is: the RS-232 'Standard' came out so
> early that it's evolved quite a lot, and been
> used in MANY form factors. It's amazing
> that it's as portable, and still works, as it is.
> There IS a specification, but I really don't think
> it calls out wire colors.
>
>
> --- In [email protected], 'Albert Catano'
> <acatano2002@y...> wrote:
> > I do not think the color coding of cables is arbitrarily.
> > If you look a telephoneman splicing hundreds of wires , they
> follow
> > a color code scheme.
> > Perhaps there is an ANSI standard (they have standards for almost
> > everythinng).
>
>
> To UNSUBSCRIBE, just send mail to:
> [email protected]
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>
> - edited 2003-09-15 - 02:01:00As Allan and others have said, there is not a standard for wire colors.
Each factory lot will use the same color sequence, but different
factories/lots will vary. We use a M-F DB9 cable for a commercial
device, by cutting the cable at one end, discarding the connector, and
wiring the cable to our circuits, using a few hundred per year. We try
to buy from the same place, but periodically check the colors and pins
to avoid circuit disasters. We like and use black cables from Jameco,
to match our black instrument cases.
Dennis
Original MessageFrom: Allan Lane [noparse][[/noparse]mailto:allan.lane@h...]
Sent: Sunday, September 14, 2003 8:24 AM
To: [email protected]
Subject: [noparse][[/noparse]basicstamps] Re: serial cable color coding
If you are a telephone man, with a 50-pair telephone
cable, you'd better have a standard for what pair
of wires goes where. If you're installing a
50 foot 8-wire cable between a PC and a Modem, you have
a lot more lattitude.
If you are installing an 'RS-232' 'Standard' cable
(ansi standard RS-232, RS-232b, RS-232c) well:
You could install a DB25 with all pins connected,
all pins defined -- but I don't think they spec
the color.
You could install a DB25 with only the common 8
lines -- RX,TX, CTS,RTS, DCD,DTR,DTS, and Ground.
Oops, forgot 'RI' (ring) used by the PC as IRQ input.
Or you could do DB9. Or you could do RJ45 (like
DEC and Stallion did). Or you could do 'three-wire'
(TX, RX and Ground).
The point is: the RS-232 'Standard' came out so
early that it's evolved quite a lot, and been
used in MANY form factors. It's amazing
that it's as portable, and still works, as it is.
There IS a specification, but I really don't think
it calls out wire colors.
--- In [email protected], 'Albert Catano'
<acatano2002@y...> wrote:
> I do not think the color coding of cables is arbitrarily.
> If you look a telephoneman splicing hundreds of wires , they
follow
> a color code scheme.
> Perhaps there is an ANSI standard (they have standards for almost
> everythinng).
To UNSUBSCRIBE, just send mail to:
[email protected]
from the same email address that you subscribed. Text in the Subject
and Body of the message will be ignored.
Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/ - edited 2003-09-15 - 02:31:00Speaking of that, does anyone still make a cable with removeable shells?
Most everything I see has molded ends, which means you have to chop off
one end and put on a fresh connector if you need to make a custom cable.
> As Allan and others have said, there is not a standard for wire colors.
> Each factory lot will use the same color sequence, but different
> factories/lots will vary. We use a M-F DB9 cable for a commercial
> device, by cutting the cable at one end, discarding the connector, and
> wiring the cable to our circuits, using a few hundred per year. We try
> to buy from the same place, but periodically check the colors and pins
> to avoid circuit disasters. We like and use black cables from Jameco,
> to match our black instrument cases. - edited 2003-09-15 - 16:08:00Bad -- Black -- 0
boys -- Brown -- 1
race -- Red -- 2
our -- Orange -- 3
young -- Yellow -- 4
girls -- Green -- 5
behind -- Blue -- 6
victory -- Violet -- 7
garden -- Gray -- 8
walls -- White -- 9
Above is a non-bawdy version of the resistor
numbering color sequence, which DOES NOT apply
(necessarily) to RS-232. ('Bad boys rape our
young girls, but violet gives willingly' is
the 'PG-13' version)
Note that CAT-5 cable has Orange/Orange-Stripe,
Blue/Blue-Stripe, Green/Green-Stripe,
Brown/Brown-Stripe. This CAN be used for
RS-232 also.
--- In [email protected], 'Stephen H Chapman'
<chapman@t...> wrote:
> Now I lay me down to sleep
> With a roll of cable at my feet
> If I should die before I wake
> White, Blue, Orange, Green, Brown, Slate.
>
>Original Message> From: 'Allan Lane' <allan.lane@h...>
> To: <[email protected]>
> Sent: Sunday, September 14, 2003 8:23 AM
> Subject: [noparse][[/noparse]basicstamps] Re: serial cable color coding
>
>
> > If you are a telephone man, with a 50-pair telephone
> > cable, you'd better have a standard for what pair
> > of wires goes where. If you're installing a
> > 50 foot 8-wire cable between a PC and a Modem, you have
> > a lot more lattitude.
> >
> > If you are installing an 'RS-232' 'Standard' cable
> > (ansi standard RS-232, RS-232b, RS-232c) well:
> > You could install a DB25 with all pins connected,
> > all pins defined -- but I don't think they spec
> > the color.
> >
> > You could install a DB25 with only the common 8
> > lines -- RX,TX, CTS,RTS, DCD,DTR,DTS, and Ground.
> > Oops, forgot 'RI' (ring) used by the PC as IRQ input.
> >
> > Or you could do DB9. Or you could do RJ45 (like
> > DEC and Stallion did). Or you could do 'three-wire'
> > (TX, RX and Ground).
> >
> > The point is: the RS-232 'Standard' came out so
> > early that it's evolved quite a lot, and been
> > used in MANY form factors. It's amazing
> > that it's as portable, and still works, as it is.
> > There IS a specification, but I really don't think
> > it calls out wire colors.
> >
> >
> > --- In [email protected], 'Albert Catano'
> > <acatano2002@y...> wrote:
> > > I do not think the color coding of cables is arbitrarily.
> > > If you look a telephoneman splicing hundreds of wires , they
> > follow
> > > a color code scheme.
> > > Perhaps there is an ANSI standard (they have standards for
almost
> > > everythinng).
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > [email protected]
> > from the same email address that you subscribed. Text in the
Subject and
> Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> >
> >
> >
> > - edited 2003-09-15 - 18:31:00I collect these.
There are many variations on the Bad boys... I have also heard Bad Beer
Rots Our Young Guts but Vodka Goes Well.
Bad Betty runs over your garden but Violet Gray won't
Billy Brown Revives On Your Gin, But Values Good Whisky
Better Be Ready, Or Your Great Big Venture Goes West
Black Beetles Running On Your Garden Bring Very Good Weather
The one about batman is unrepeatable but the clean version is
Batman Bests Robin On Yonder Gotham Bridge; Very Good, Will Get
Superman Next
Al Williams
AWC
* Add floating point math to your Stamp program:
http://www.al-williams.com/pak1.htm
>Original Message> From: Allan Lane [noparse][[/noparse]mailto:allan.lane@h...]
> Sent: Monday, September 15, 2003 10:09 AM
> To: [email protected]
> Subject: [noparse][[/noparse]basicstamps] Re: serial cable color coding
>
>
> Bad -- Black -- 0
> boys -- Brown -- 1
> race -- Red -- 2
> our -- Orange -- 3
> young -- Yellow -- 4
> girls -- Green -- 5
> behind -- Blue -- 6
> victory -- Violet -- 7
> garden -- Gray -- 8
> walls -- White -- 9
>
> Above is a non-bawdy version of the resistor
> numbering color sequence, which DOES NOT apply
> (necessarily) to RS-232. ('Bad boys rape our
> young girls, but violet gives willingly' is
> the 'PG-13' version)
>
> Note that CAT-5 cable has Orange/Orange-Stripe,
> Blue/Blue-Stripe, Green/Green-Stripe,
> Brown/Brown-Stripe. This CAN be used for
> RS-232 also.
>
> --- In [email protected], 'Stephen H Chapman'
> <chapman@t...> wrote:
> > Now I lay me down to sleep
> > With a roll of cable at my feet
> > If I should die before I wake
> > White, Blue, Orange, Green, Brown, Slate.
> >
> >Original Message> > From: 'Allan Lane' <allan.lane@h...>
> > To: <[email protected]>
> > Sent: Sunday, September 14, 2003 8:23 AM
> > Subject: [noparse][[/noparse]basicstamps] Re: serial cable color coding
> >
> >
> > > If you are a telephone man, with a 50-pair telephone
> > > cable, you'd better have a standard for what pair
> > > of wires goes where. If you're installing a
> > > 50 foot 8-wire cable between a PC and a Modem, you have
> > > a lot more lattitude.
> > >
> > > If you are installing an 'RS-232' 'Standard' cable
> > > (ansi standard RS-232, RS-232b, RS-232c) well:
> > > You could install a DB25 with all pins connected,
> > > all pins defined -- but I don't think they spec
> > > the color.
> > >
> > > You could install a DB25 with only the common 8
> > > lines -- RX,TX, CTS,RTS, DCD,DTR,DTS, and Ground.
> > > Oops, forgot 'RI' (ring) used by the PC as IRQ input.
> > >
> > > Or you could do DB9. Or you could do RJ45 (like
> > > DEC and Stallion did). Or you could do 'three-wire'
> > > (TX, RX and Ground).
> > >
> > > The point is: the RS-232 'Standard' came out so
> > > early that it's evolved quite a lot, and been
> > > used in MANY form factors. It's amazing
> > > that it's as portable, and still works, as it is.
> > > There IS a specification, but I really don't think
> > > it calls out wire colors.
> > >
> > >
> > > --- In [email protected], 'Albert Catano'
> > > <acatano2002@y...> wrote:
> > > > I do not think the color coding of cables is
> arbitrarily. If you
> > > > look a telephoneman splicing hundreds of wires , they
> > > follow
> > > > a color code scheme.
> > > > Perhaps there is an ANSI standard (they have standards for
> almost
> > > > everythinng).
> > >
> > >
> > > To UNSUBSCRIBE, just send mail to:
> > > [email protected]
> > > from the same email address that you subscribed. Text in the
> Subject and
> > Body of the message will be ignored.
> > >
> > >
> > > Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
> > >
> > >
> > >
> > >
>
>
> To UNSUBSCRIBE, just send mail to:
> [email protected]
> from the same email address that you subscribed. Text in the
> Subject and Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/ - edited 2003-09-15 - 18:42:00Could you send me the R or X versions off list.
Larry Gaminde
Original MessageFrom: 'Al Williams' <alw@a...>
To: <[email protected]>
Sent: September 15, 2003 10:31 AM
Subject: RE: [noparse][[/noparse]basicstamps] Re: serial cable color coding
> I collect these.
>
> There are many variations on the Bad boys... I have also heard Bad Beer
> Rots Our Young Guts but Vodka Goes Well.
>
> Bad Betty runs over your garden but Violet Gray won't
>
> Billy Brown Revives On Your Gin, But Values Good Whisky
>
> Better Be Ready, Or Your Great Big Venture Goes West
>
> Black Beetles Running On Your Garden Bring Very Good Weather
>
> The one about batman is unrepeatable but the clean version is
> Batman Bests Robin On Yonder Gotham Bridge; Very Good, Will Get
> Superman Next
>
> Al Williams
> AWC
> * Add floating point math to your Stamp program:
> http://www.al-williams.com/pak1.htm
>
>
> >Original Message> > From: Allan Lane [noparse][[/noparse]mailto:allan.lane@h...]
> > Sent: Monday, September 15, 2003 10:09 AM
> > To: [email protected]
> > Subject: [noparse][[/noparse]basicstamps] Re: serial cable color coding
> >
> >
> > Bad -- Black -- 0
> > boys -- Brown -- 1
> > race -- Red -- 2
> > our -- Orange -- 3
> > young -- Yellow -- 4
> > girls -- Green -- 5
> > behind -- Blue -- 6
> > victory -- Violet -- 7
> > garden -- Gray -- 8
> > walls -- White -- 9
> >
> > Above is a non-bawdy version of the resistor
> > numbering color sequence, which DOES NOT apply
> > (necessarily) to RS-232. ('Bad boys rape our
> > young girls, but violet gives willingly' is
> > the 'PG-13' version)
> >
> > Note that CAT-5 cable has Orange/Orange-Stripe,
> > Blue/Blue-Stripe, Green/Green-Stripe,
> > Brown/Brown-Stripe. This CAN be used for
> > RS-232 also.
> >
> > --- In [email protected], 'Stephen H Chapman'
> > <chapman@t...> wrote:
> > > Now I lay me down to sleep
> > > With a roll of cable at my feet
> > > If I should die before I wake
> > > White, Blue, Orange, Green, Brown, Slate.
> > >
> > >Original Message> > > From: 'Allan Lane' <allan.lane@h...>
> > > To: <[email protected]>
> > > Sent: Sunday, September 14, 2003 8:23 AM
> > > Subject: [noparse][[/noparse]basicstamps] Re: serial cable color coding
> > >
> > >
> > > > If you are a telephone man, with a 50-pair telephone
> > > > cable, you'd better have a standard for what pair
> > > > of wires goes where. If you're installing a
> > > > 50 foot 8-wire cable between a PC and a Modem, you have
> > > > a lot more lattitude.
> > > >
> > > > If you are installing an 'RS-232' 'Standard' cable
> > > > (ansi standard RS-232, RS-232b, RS-232c) well:
> > > > You could install a DB25 with all pins connected,
> > > > all pins defined -- but I don't think they spec
> > > > the color.
> > > >
> > > > You could install a DB25 with only the common 8
> > > > lines -- RX,TX, CTS,RTS, DCD,DTR,DTS, and Ground.
> > > > Oops, forgot 'RI' (ring) used by the PC as IRQ input.
> > > >
> > > > Or you could do DB9. Or you could do RJ45 (like
> > > > DEC and Stallion did). Or you could do 'three-wire'
> > > > (TX, RX and Ground).
> > > >
> > > > The point is: the RS-232 'Standard' came out so
> > > > early that it's evolved quite a lot, and been
> > > > used in MANY form factors. It's amazing
> > > > that it's as portable, and still works, as it is.
> > > > There IS a specification, but I really don't think
> > > > it calls out wire colors.
> > > >
> > > >
> > > > --- In [email protected], 'Albert Catano'
> > > > <acatano2002@y...> wrote:
> > > > > I do not think the color coding of cables is
> > arbitrarily. If you
> > > > > look a telephoneman splicing hundreds of wires , they
> > > > follow
> > > > > a color code scheme.
> > > > > Perhaps there is an ANSI standard (they have standards for
> > almost
> > > > > everythinng).
> > > >
> > > >
> > > > To UNSUBSCRIBE, just send mail to:
> > > > [email protected]
> > > > from the same email address that you subscribed. Text in the
> > Subject and
> > > Body of the message will be ignored.
> > > >
> > > >
> > > > Your use of Yahoo! Groups is subject to
> > http://docs.yahoo.com/info/terms/
> > > >
> > > >
> > > >
> > > >
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > [email protected]
> > from the same email address that you subscribed. Text in the
> > Subject and Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
>
>
>
> To UNSUBSCRIBE, just send mail to:
> [email protected]
> from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
> - edited 2003-09-16 - 01:05:00Just remember, B is blue, while black is K on alot of diagrams.
> I collect these.
>
> There are many variations on the Bad boys... I have also heard Bad Beer
> Rots Our Young Guts but Vodka Goes Well.
>
> Bad Betty runs over your garden but Violet Gray won't
>
> Billy Brown Revives On Your Gin, But Values Good Whisky
>
> Better Be Ready, Or Your Great Big Venture Goes West
>
> Black Beetles Running On Your Garden Bring Very Good Weather
>
> The one about batman is unrepeatable but the clean version is
> Batman Bests Robin On Yonder Gotham Bridge; Very Good, Will Get
> Superman Next
RS232 serial cable layout
Almost nothing in computer interfacing is more confusing than selecting the right RS232 serial cable. These pages are intended to provide information about the most common serial RS232 cables in normal computer use, or in more common language “How do I connect devices and computers using RS232?”
RS232 serial connector pin assignment
Db25 Pinout Colors Meaning
The RS232 connector was originally developed to use 25 pins. In this DB25 connector pinout provisions were made for a secondary serial RS232 communication channel. In practice, only one serial communication channel with accompanying handshaking is present. Only very few computers have been manufactured where both serial RS232 channels are implemented. Examples of this are the Sun SparcStation 10 and 20 models and the Dec Alpha Multia. Also on a number of Telebit modem models the secondary channel is present. It can be used to query the modem status while the modem is on-line and busy communicating. On personal computers, the smaller DB9 version is more commonly used today. The diagrams show the signals common to both connector types in black. The defined pins only present on the larger connector are shown in red. Note, that the protective ground is assigned to a pin at the large connector where the connector outside is used for that purpose with the DB9 connector version.
The pinout is also shown for the DEC modified modular jack. This type of connector has been used on systems built by Digital Equipment Corporation; in the early days one of the leaders in the mainframe world. Although this serial interface is differential (the receive and transmit have their own floating ground level which is not the case with regular RS232) it is possible to connect RS232 compatible devices with this interface because the voltage levels of the bit streams are in the same range. Where the definition of RS232 focused on the connection of DTE, data terminal equipment (computers, printers, etc.) with DCE, data communication equipment (modems), MMJ was primarily defined for the connection of two DTE’s directly.
Db9 To Db25 Pinout
DEC MMJ pinout
RS232 DB25 to DB9 converter
The original pinout for RS232 was developed for a 25 pins sub D connector. Since the introduction of the smaller serial port on the IBM-AT, 9 pins RS232 connectors are commonly used. In mixed applications, a 9 to 25 pins converter can be used to connect connectors of different sizes. As most of the computers are equipped with the DB9 serial port version, all wiring examples on this website will use that connector as a default. If you want to use the example with a DB25, simply replace the pin numbers of the connector according to the conversion table below.
DB9 | DB25 | Function |
---|---|---|
1 | 8 | Data carrier detect |
2 | 3 | Receive data |
3 | 2 | Transmit data |
4 | 20 | Data terminal ready |
5 | 7 | Signal ground |
6 | 6 | Data set ready |
7 | 4 | Request to send |
8 | 5 | Clear to send |
9 | 22 | Ring indicator |
RS232 serial loop-back test plugs
The following RS232 connectors can be used to test a serial port on your computer. The data and handshake lines have been linked. In this way all data will be sent back immediately. The PC controls its own handshaking. The first test plug can be used to check the function of the RS232 serial port with standard terminal software. The second version can be used to test the full functionality of the RS232 serial port with Norton Diagnostics or CheckIt.
RS232 loop-back test plug for terminal emulation software
DB9 | DB25 | Function | ||
---|---|---|---|---|
1 + 4 + 6 | 6 + 8 + 20 | DTR | ⇒ | CD + DSR |
2 + 3 | 2 + 3 | Tx | ⇒ | Rx |
7 + 8 | 4 + 5 | RTS | ⇒ | CTS |
RS232 loopback test plug for Norton Diagnostics and CheckIt
DB9 | DB25 | Function | ||
---|---|---|---|---|
1 + 4 + 6 + 9 | 6 + 8 + 20 + 22 | DTR | ⇒ | CD + DSR + RI |
2 + 3 | 2 + 3 | Tx | ⇒ | Rx |
7 + 8 | 4 + 5 | RTS | ⇒ | CTS |
Testing occurs in a few steps. Data is sent on the Tx line and the received information on the Rx input is then compared with the original data.
The signal level on the DTR and RTS lines is also controlled by the test software and the attached inputs are read back in the software to see if these signal levels are properly returned. The second RS232 test plug has the advantage that the ring-indicator RI input line can also be tested. This input is used by modems to signal an incoming call to the attached computer.
RS232 null modem cables
The easiest way to connect two PC’s is using an RS232 null modem cable. The only problem is the large variety of RS232 null modem cables available. For simple connections, a three line RS232 cable connecting the signal ground and receive and transmit lines is sufficient. Depending of the software used, some sort of handshaking may however be necessary. Use the RS232 null modem selection table to find the right null modem cable for each purpose. For a Windows 95/98/ME Direct Cable Connection, the RS232 null modem cable with loop back handshaking is a good choice.
RS232 null modem cables with handshaking can be defined in numerous ways, with loop-back handshaking to each PC, or complete handshaking between the two systems. The most common null modem cable types are shown here.
Simple RS232 null modem without handshaking (Null modem explanation)
Connector 1 | Connector 2 | Function | ||
---|---|---|---|---|
2 | 3 | Rx | ⇐ | Tx |
3 | 2 | Tx | ⇒ | Rx |
5 | 5 | Signal ground |
RS232 null modem with loop back handshaking (Null modem explanation)
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Db25 Pinout Colors Types
Connector 1 | Connector 2 | Function | ||
---|---|---|---|---|
2 | 3 | Rx | ⇐ | Tx |
3 | 2 | Tx | ⇒ | Rx |
5 | 5 | Signal ground | ||
1 + 4 + 6 | – | DTR | ⇒ | CD + DSR |
– | 1 + 4 + 6 | DTR | ⇒ | CD + DSR |
7 + 8 | – | RTS | ⇒ | CTS |
– | 7 + 8 | RTS | ⇒ | CTS |
Db25 Pinout Diagram
RS232 null modem with partial handshaking (Null modem explanation)
Connector 1 | Connector 2 | Function | ||
---|---|---|---|---|
1 | 7 + 8 | RTS2 | ⇒ | CTS2 + CD1 |
2 | 3 | Rx | ⇐ | Tx |
3 | 2 | Tx | ⇒ | Rx |
4 | 6 | DTR | ⇒ | DSR |
5 | 5 | Signal ground | ||
6 | 4 | DSR | ⇐ | DTR |
7 + 8 | 1 | RTS1 | ⇒ | CTS1 + CD2 |
RS232 null modem with full handshaking (Null modem explanation)
Connector 1 | Connector 2 | Function | ||
---|---|---|---|---|
2 | 3 | Rx | ⇐ | Tx |
3 | 2 | Tx | ⇒ | Rx |
4 | 6 | DTR | ⇒ | DSR |
5 | 5 | Signal ground | ||
6 | 4 | DSR | ⇐ | DTR |
7 | 8 | RTS | ⇒ | CTS |
8 | 7 | CTS | ⇐ | RTS |