hook-up of PC as DEC VT220 terminal to Micro-Vax II

hook-up of PC as DEC VT220 terminal to Micro-Vax II

Post by luke j. schippe » Tue, 14 Oct 1997 04:00:00



I have a Micro-Vax II which was located elsewhere before and I used my
PC to work with the system, by use of Modems and Pro-Com - it worked
fine.
I now have the Micro-Vax at my site and want to also be able to use my
PC as a terminal of the Micro-Vax II, thus direct hard-wired, but
thusfar I have not been able to come up with correct pin layout-cable
connection (e.g. like a null-modem) to make this happen.
At the PC end, I know I must 'fool' my PC by jumpering pins 4 and 5, and
also jumper pins 6, 8 and 20 and, if necessary, reverse 2 and 3 in the
cable. However, my Micro-Vax still does not want to listen to my PC.
On the Micro-Vax I am using the DHV-11 async. controller.

Anybody out there who can shed some light on this for me
Much appreciated

 
 
 

hook-up of PC as DEC VT220 terminal to Micro-Vax II

Post by V. M. Ha » Mon, 20 Oct 1997 04:00:00



   I have a Micro-Vax II which was located elsewhere before and I used my
   PC to work with the system, by use of Modems and Pro-Com - it worked
   fine.
   I now have the Micro-Vax at my site and want to also be able to use my
   PC as a terminal of the Micro-Vax II, thus direct hard-wired, but
   thusfar I have not been able to come up with correct pin layout-cable
   connection (e.g. like a null-modem) to make this happen.

If you can find one, take a straight-through cable assembly and combine it with a
null-modem adaptor, gender to fit.

   At the PC end, I know I must 'fool' my PC by jumpering pins 4 and 5, and
   also jumper pins 6, 8 and 20 and, if necessary, reverse 2 and 3 in the
   cable. However, my Micro-Vax still does not want to listen to my PC.
   On the Micro-Vax I am using the DHV-11 async. controller.

At the PC end, tell your comms program to ignore the modem control leads (Kermit
works). Your PC is probably much faster than the uVAX (unless it is a ca. 1981
IBM-PC) so the control leads won't help, anyway.

   Anybody out there who can shed some light on this for me
   Much appreciated

-- Mark
--
-- Mark
   NetBSD Lives!!

 
 
 

1. Micro VAX II > VT220


For the console terminal, you need to connect up to the 9-pin
connector (which is not compatible with a PC's 9 pin serial
port). You may be getting some kind of error message there.

The 9-pin is wired like this (or it may need to be nulled,
this is taken from a VT220 manual)

1 - Protective ground
2 - Transmit data
3 - Receive data
4 - Request to send (RTS)
5 - Data terminal ready (DTR)
6 - Data set ready (DSR)
7 - Signal ground

So your cable shoul be either

9-pin    25pin
2--------2
3--------3
7--------7

or
2--------3
3--------2
7--------7

as a minimum. I don't have a uVaxII of my own any more,
so can't test this directly.

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