sio2pc versus P:R: Connetion

[suspicious_milk]

lets make this perfectly clear...

you must use an Atari specific rs232 cable...

you can then use industry standard null modem adapter attached to the end of that cable...

you can not use standard cable from ibm pc it is not wired correctly

you can not put the adapter directly into the 850/pr/mio.... the pins are wired completely wrong for that purpose and will translate incorrectly

 

the horse must always be in front of the carriage otherwise kaboom!

 

Perfect. Thank You.

[flashjazzcat]

It's been quite a journey to get here. I've been looking for a working wiring plan for a year and have received about half a dozen different suggestions. The Doctor's definitive advice should be carved in stone some place.

[suspicious_milk]

Ha, yeah. Thanks FJC, I've read thru a lot of threads and there's a bit of contradicting info & trial/error. Of course, had I re-read this very thread my last question I had was already addressed :-[ BillC's suggestion on looking up DTE/DCE was most informative.

[_The Doctor__]

The long explanation why

 

x086 PC db9 MALE(pins stick out shield surrounds) pin/function 1/dcd 2/rxd 3/txd 4/dtr 5/gnd 6/dsr 7/rts 8/cts 9/ri plugs into pc case to shield hood/braid

Atari PR db9 MALE(pins stick out shield surrounds) pin/function 1/dtr 2/dcd 3/txd 4/rxd 5/gnd 6/dsr 7/rts 8/cts 9/nc plugs into pr no shield

 

you can see these will not match up when plugged in with only pins 5-8 match, adding an adapter before the cable really scrambles the pinout further making it totally useless

 

both cables end up with db25 the exact same way

both db25 MALE(pins stick out shield surrounds) pin/function 2/txd 3/rxd 4/rts 5/cts 6/dsr 7/gnd 8/dcd 20/dtr 22/ri

 

since both end with the same industry standard db25 you can add whatever adapter you want from the db25 on...

 

ps db9 null cable tie pins 6 and 1 together on the db9s and connect to pin 4.. on the atari this will tie dsr dtr and rcv it effectively kills receiving of data

 

that is why it's best to keep cx87 (850 PR MIO) standard cable and adapt from db 25 on... But you can easily make a custom cable now from the above

pinouts,

 

now this is where most people get lost.... male pinouts go from left to right top to bottom and female pinouts go from right to left top to bottom

male 1 2 3 4 5

6 7 8 9

 

female 5 4 3 2 1

9 8 7 6

 

when you turn them to face each other 1 goes into 1 etc etc. till 9 into 9 a perfect line up

 

db 25 same thing

 

male 1 2 3 4 5 6 7 8 9 10 11 12 13

14 15 16 17 18 19 20 21 22 23 24 25

 

female 13 12 11 10 9 8 7 6 5 4 3 2 1

25 24 23 22 21 20 19 18 17 16 15 14

 

many times if you forget this the cable gets wired reversed 2 becomes 12.... etc... you can see what that does...

Edited March 8, 2014 by _The Doctor__

[flashjazzcat]

Well it wasn't the pin numbering in my case but the copious information sure is appreciated. I'll be double-checking my cable against this later. Thanks again!