At 07:02 PM 7/16/2000 +0200, you wrote:
>Hi everyone,
>
>I was wondering how long the console cable of my VAX 4000/300 can be... I
>want to hook it to a terminal in my room, which is about 50 meters away from
>my VAX. Is this possible? I think it is, but I just want to be sure :)
>
>--Rink

Well, I've got a MicroVax 3300, and I've had success using the 
'differential' over cat5 cabling to RS-232.

I have a pinout for the vax of:

1 -> Ready Out
2 -> TX+
3 -> TX-
4 -> RX-
5 -> RX+
6 -> Ready In

Normally, you tie the RX- and TX- together to make a ground. What I did is 
use 3 pair of a Cat5 cable to make the link as follows

Vax             RJ-45           DB-25

1               Orange          20
2               Green           2
3               green/white     7
4               blue/white      7
5               Blue            3
6               orange/white    6&8

Pin 7 on the DB-25 is the common tie point for RX-/TX-.

Note that this wiring scheme puts RX+ and RX- on one twisted pair, which 
cuts down on interference. Same for TX+/TX- of course.  This let me go from 
~90 feet w/o errors on flat satin cable @ 9600 to 150+ Feet on Cat5 at 19200.

Also, the slower you go on RS-232, the farther you can go. The oft-quoted 
50 feet spec is for 9600 Baud.

Trivia for the Microvax 3300 (maybe other KA640's?)
On the back of the control/status panel that sits in front of the KA640 is 
a thumbwheel. This thumbwheel sets the baud rate for the console, up to 
38400. 19200 works very well for me, and the console speed is MUCH nicer.
Not to mention which, if you're a security fanatic, who thinks to connect 
to a VAX at anything other than 9600?

In case you have no handy sticker, here are the thumbwheel settings:

0       300 Baud
1       600
2       1200
3       2400
4       4800
5       9600
6       19200
7       38400


Good Luck
Paul Tice
ptice@p2.net
lpt1@cyber-wizard.com