28 Nov
2013
28 Nov
'13
7:21 a.m.
On Thu, Nov 28, 2013 at 7:02 AM, Paul Koning <paulkoning at comcast.net> wrote:
On Nov 27, 2013, at 10:09 PM, Al Kossow <aek at bitsavers.org> wrote:
Some standard PDP-11 SLU interface supports RS-422 differential signaling.
http://www.bitsavers.org/pdf/dec/qbus
EB-23144-18_QbusIntrfs_1983.pdf
See manual page 266 (PDF page 276) and manual pages 285-286 (PDF pages
295 -296) for an example of how this works on the DLV11-J.
The M8189 PDP-11/23 SLU interface is similar.
Don't forget rx and tx are actually differential receivers and
drivers. Tie rx- (7) to ground (9) on the 10 pin connector.
I'm puzzled. RS232 is single ended, not differential. It does need a ground
reference, of course, so you have to make sure the signal ground wire is connected
properly.