
January 4, 1996

When I received my cable from Elek-Tek I first tested it on a PC.
Using PC-Link software from a friend I verified that it worked.
When I tried the serial port on my Sparc station I was totally
unsuccessful in getting any character I/O to occur. Using a
RS-232 break-out-box I came up with the following wiring
arrangement that worked:

	<- Sparc	PC-LINK cable ->

	 2 --------------------- 2	(TD - Transmitted Data)		->

	 3 --------------------- 3	(RD - Received Data)		<-

	 4 ---- N.C.	 +----+- 4	(RTS - Request To Send)		->
			 |    |
	 5 ---- N.C.	 |    +- 5	(CTS - Clear To Send)		<-
			 |
	 7 --------------------- 7	(SG - Signal Ground)
			 |
	20 -------------------- 20	(DTR - Data Terminal Ready)	->
			 |
	24 --------------+		(ETC - Ext Transmitter Clock)	->


	Don't bother with any of the other RS-232 lines.

According to the RS-232 specifications pin 24 is labeled "(E)TC"
which I assume means extra. transmitter clock. On the Sparc's
that I have tested, this line is at a constant -12v. This is fortunate
because without this voltage source, the circuit inside the
cable does not function.

SUN3 NOTE:
The old (ancient) sun3 machines have different signals and pin 24 does
not generate -12v. I have had no luck getting Sun 3's to work with my
Elek-Tek cable.

- Ken Stauffer (kstauffer@attmail.com)
