UTP ethernet cable (10 base T & 100 base T, twisted pair)
---------------------------------------------------------
A normal cable is connected pin to pin, with RJ-45 Male Plug pin numbers
twisted pairs on pins 1/2, 3/6, 4/5 and 7/8. as seen from the front.
/ /
A crossover (or "cascade") cable /_ _ _ _ _ _ _ _ _ /
crosses over the 1/2 & 3/6 pairs | # # # # # # # # | /
(ie. connect pin 1 at one end to | 8 1 | /
pin 3 at the other, the same for |____ ____|/
pins 2 & 6, the rest pin to pin. |_______|/
Crossover (1x3 & 2x6) end of cascade
Normal connections, pin to pin. cable. (Other end is normal)
Signal Pin Colour(s) 1x3 Pin Colour(s) Twist.pairs
TxData+ 1 Orange/white ---. ,--- 2x6 1 Green/white --. 1
TxData- 2 Orange X ---. ,--- 2 Green --' 2
RxData+ 3 Green/white ---' `--- \ / 3 Orange/white -------.
unused 4 Blue X 4 Blue --. 4 | 3
unused 5 Blue/white / \ 5 Blue/white --' 5 | 6
RxData- 6 Green ---' `--- 6 Orange -------'
unused 7 Brown/white 7 Brown/white --. 7
unused 8 Brown 8 Brown --' 8
When using UTP wiring to carry 2 wire telephone connections, connect
'phone line A (red) to RJ-45 pin 4, & phone line B (green) to pin 5.
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Telephone cables
BT431A plug BT ---------------- RJ-11 Plug pin
/ / standard pin / / numbers /
/ / numbering / /_ _ _ _ _ _ _ /
|\/_ _ _ _ _ _ _ / | # # # # # # | /
| | # # # # # # | / | 6 1 | /
| | 1 6 | / |__ __|/
\|_____________|/ |_______|/
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RS232 cable, normal 25 pin (DB25), 9 pin (DB9) & some RJ45 pinouts
------------------------------------------------------------------
________________________________________ ___________
( 1 2 3 4 5 6 7 8 9 10 11 12 13 ) ( 1 2 3 4 5 )
DB25 \ 14 15 16 17 18 19 20 21 22 23 24 25 / \ 6 7 8 9 / DB9
`------------------------------------' `-------'
Front views of a plug (or the back of a socket, ie. the side the cable is
attached to). The other views are a left to right mirror image of this.
DB9 DB25
Pin Pin Signal assignment DCE DTE Asserted
------------------------------------------------------------------------------
N/A 1 FRM (Frame ground) -- ---
1 8 DCD CD (Data Carrier Detect) out -> in High high = mark = -ve
2 3 RXD RD (Receive Data) out -> in Low low = space = +ve
3 2 TXD TD (Transmit Data) in 4 20 DTR TR (Data Terminal Ready) in 5 7 GND SG (Signal Ground) -- --- Equipment, eg. modems.
6 6 DSR DR (Data Set Ready) out -> in High
7 4 RTS RS (Request To Send) in 8 5 CTS CS (Clear To Send) out -> in High eg. computers, terminals
9 22 RI (Ring Indicator) out -> in High and most printers.
Connect pin to pin between DTE & DCE, or a "null modem" between two DTEs:
DB9 DB25 | Null Modem: DB9 DB25
Pin Pin Signal assignment | Cross connect Pins Pins
----------------------------------------+-----------------------------------
N/A 1 FRM (Frame ground) | Frame ground N/A 1 - 1
1 8 DCD CD (Data Carrier Detect) | DSR+DCD x DTR 6+1 x 4 6+8 x 20
2 3 RXD RD (Receive Data) | RXD x TXD 2 x 3 3 x 2
3 2 TXD TD (Transmit Data) | TXD x RXD 3 x 2 2 x 3
4 20 DTR TR (Data Terminal Ready) | DTR x DSR+DCD 4 x 6+1 20 x 6+8
5 7 GND SG (Signal Ground) | GND - GND 5 - 5 7 - 7
6 6 DSR DR (Data Set Ready) | DSR+DCD x DTR 6+1 x 4 6+8 x 20
7 4 RTS RS (Request To Send) | RTS x CTS 7 x 8 4 x 5
8 5 CTS CS (Clear To Send) | CTS x RTS 8 x 7 5 x 4
9 22 RI (Ring Indicator) | No connection No connection
RJ45 pin -> 1 2 3 4 5 6 7 8
Alcatel console (DCE) RXD RTS N/C TXD GND CTS N/C RI
Cisco console (DTE) CTS DTR TXD GND GND RXD DSR RTS
Sun Netra 120, v100 (DTE) RTS DTR TXD GND GND RXD DSR CTS
Annex term serv (DTE) RTS DTR TXD DCD RXD GND DSR CTS
Magma serial card (DTE) RTS TXD RXD DTR CTS DSR GND DCD
or may be reversed... DCD GND DSR CTS DTR RXD TXD RTS
3com 3CDSG8 managed switch (DTE) DCD RXD TXD DTR GND DSR RTS CTS
A "roll cable" (reversed order of pins, connecting 1-8, 2-7, 3-6, 4-5)
works as an RJ45 null modem cable for Sun Netras & V100s, and Ciscos.
RS232 Electrical Specs. 1 = high = mark = -ve voltage
_ _ ___ _ 0 = low = space = +ve voltage
____/|\___/ \_/ \_/ \_____ Idle state is 1. Data is sent
Idle | 1 1 0 1 0 0 1 0 | Idle as a start bit (0), data bits
| +--Data bits--+ | LS first, and stop bit(s) (1)
Start Stop 'K' = 0x4B = 01001011 binary.
The requirements for a driver (output) and receiver (input) are simple:
1. A receiver may present a load ranging from 3000 ohm to 7000 ohm,
and expects signals to swing from above +3 volt to below -3 volt.
2. A driver must have an output resistance of at least 300 ohm and present a
swing of above +5 volt to below -5 volt to a receiver. Open circuit driver
voltage is as high as +-25v, but must drop to +-15 with receiver load.
Most receiver chips switch in the range of 0.5 to 2 volt. (Still within RS232
specs.) It all of them did we could drive them from circuits that swing only
down to ground, but some must be driven below ground. One serial port board
tested used a 75174 based receiver which needed a voltage swing down to -1v.
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For HP plotters use MODE 9600,N,8,1,P; RS-232-C serial cable pin outs are:
25-pin to 25-pin cable 25-pin to 9-pin cable
Plotter Computer Plotter(DB25) Computer(DB9)
FRM 1----1 FRM RTS 4----1 DCD
TXD 2----3 RXD TXD 2----2 RXD
RXD 3----2 TXD RXD 3----3 TXD
GND 7----7 GND CTS+DSR 5+6--4 DTR
DTR 20--5+6 CTS+DSR GND 7----5 GND
CTS+DSR 5+6--20 DTR DTR 20--6+8 DSR+CTS
DCD 8----7 RTS
Posted in: Configuration