FAQ / Cable configuration



	  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.
_______________________________________________________________________________

				Telephone cables
	 BT431A plug BT		----------------       RJ-11 Plug pin
     /	/ standard pin /			     /	  numbers   /
    /  /   numbering  /				    /_ _ _ _ _ _ _ /
    |\/_ _ _ _ _ _ _ /				    | # # # # # # |  /
    | | # # # # # # |  /			    | 6		1 | /
    | | 1	  6 | /				    |__		__|/
     \|_____________|/				       |_______|/

_______________________________________________________________________________

      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.
______________________________________________________________________________

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