From: John E. Malmberg [wb8tyw@qsl.net]
Sent: Monday, August 09, 1999 1:34 AM
To: Info-VAX@Mvb.Saic.Com
Subject: Re: need help with serial connection, etc

Juergen Kortgen wrote in message <37ADF0F0.31E4445F@informatik.uni-kl.de>...
>Hello,
>
>if you have time to make your own cable, check out this:
>I recently checked the connections from serial line out pins to MMJ:
>
>PC  MMJ      with MMJ-build up:
>1    1         +--+
>2    2         |  |
>3    5       +-+  +--------+
>4    6       | 1 2 3 4 5 6 |
>5    3       +-------------+
>6
>7
>8
>9
>

The above is missing the required "Receive Ground" signal connection.

The MMJ connector has two independent signal grounds.  When adapting it to
an RS-232 connector of any variety, they must be tied together.

In this case, you must connect both pins 3 and 4 from the MMJ  to pin 5 of
the PC-AT 9 pin connector.

See Topic MISC1 in the OpenVMS FAQ at http://www.openvms.digital.com and
other places.

-John
Who is tired of troubleshooting intermittent serial communications problems
because of this common wiring error.