RS-232 Information This is a LONG message..... 1 2 3 4 5 6 7 . . . . . . . . . . . . . 14 15 16 17 18 19 etc., looking at connector pins of M100 Defintions of pin assignments for RS-232: na means "common, or not assigned" DCE means "data communications equipment" ie the modem. DTE means the "terminal" 1. earth ground na 2. transmit data to DCE 3. receive data to DTE 4. request to send to DCE 5. clear to send to DTE 6. data set ready to DTE 7. logic ground na 8. carrier detect to DTE 9. reserved na 10. reserved na 11. unassigned na 12. second carrier detect to DTE 13. second clear to send to DTE 14. second transmit data to DCE 15. transmit clock to DTE 16. second receive data to DTE 17. receive clock to DTE 18. unassigned na 19. second request to send to DCE 20. data terminal ready to DCE 21. signal qual. detect to DTE 22. ring detect to DTE 23. data rate select to DCE 24. transmit clock to DCE 25. unassigned na (second means "secondary") "BASIC 8" Pins 1-7, 20 are used in the M100 connector. To connect M100 to M100: 1 & 7: are grounds, and stay as is. 2 & 3: swap these. 4 & 6: swap these. 5 & 20: swap these. pin(t) from to pin(m) ------ ---- ---- ------ 1 ground ground 1 2 term modem 3 3 modem term 2 4 term modem 6 5 modem term 20 6 modem term 4 7 ground ground 7 20 term modem 5 These are the only pins used by the M100 to communicate. (I tried configuring my Northstar to be a "term"inal instead of a "modem", and this works with proper handshaking. UNFORTUNATELY, most printer manufacturers use these signals IMPROPERLY! If you have an 8251 instead of an 8251A USART, then you CANNOT be assured of proper handshaking. The 8251 will stop in the middle of a character, while the 8251A does not. Thus, you will LOSE part or all of a character if you attempt to tie to an 8251, if in the middle when DTR or DSR is changed by the M100, which it will do. I found out the hard way, and now have 8251A's in my Northstar, which allow 9600 baud operation.) Additional note, this worked with my Northstar, but may not work with your particular arrangement. Be warned! I hope this has been help to SOMEONE out there! If you find that I have made a mistake here, please feel free to comment, correct, chastise, or whatever is appropriate! I can be reached at ID [74405,1177] or 619-690-3475 or 4545 if you have any questions on this. No guarantees on answers, though..... ...rowlfe... (uploaded 17 AUG 84 @ 2130 PDT)