rk@bigbroth.UUCP (rohan kelley) (05/15/89)
I'm trying to make a direct connect between a bell tech 386/25 and a 3b2/400. The port on the 386 is an ace intelligent port board with 8 modular ports and on the 3b2 an enhanced port board. I'm trying to construct a modular null modem cable. This is the wiring diagram I've come up with, but haven't tried it yet. Does anybody know if this is correct? 386/ace board 3b2/enhanced ports board 1 G <-----------------------------------------> G 2 CTS <------| |-----------> CTS | | 3 TDXO<......|........\/------------|-----------> TDXO | /\ | 4 DTR <------|------\/ \/..........|...........> DTR | /\ /\ | 5 RXDO<------|-----/ \/ \.........|............> RXDO | /\ | 6 DCD <......|......./ \-----------|------------> DCD | | 7 G <------|----------------------|------------> G | | 8 RTS <------| |------------> RTS What I'm trying to say is: G 1 to 1 G CTS 2 tie to 8 (plug) TDXO 3 to 5 RXDO DTR 4 to 6 DCD RXDO 5 to 3 TDXO DCD 6 to 4 DTR G 7 to 7 G RTS 8 tie to 2 (plug) Neither the 386 or 3b2 have DSR (RS232 pin 6) which is usually tied to DTR. Is it needed? ======================================================================= Rohan Kelley -- UNIleX Systems, Inc. (Systems and software for lawyers) UUCP: ...{gatech!uflorida,ucf-cs}!novavax!bigbroth!rk (office) novavax!mdlbrotr!rk (home) ATTmail: attmail!bigbroth!rk 3365 Galt Ocean Drive, Ft. Lauderdale, FL 33308 Phone: (305) 563-1504 "Go first class or your heirs will" -somebodyelse =======================================================================
julian@bongo.UUCP (julian macassey) (05/16/89)
In article <433@bigbroth.UUCP>, rk@bigbroth.UUCP (rohan kelley) writes: > I'm trying to make a direct connect between a bell tech 386/25 and > a 3b2/400. The port on the 386 is an ace intelligent port board > with 8 modular ports and on the 3b2 an enhanced port board. > > I'm trying to construct a modular null modem cable. This is the > wiring diagram I've come up with, but haven't tried it yet. Does > anybody know if this is correct? > > What I'm trying to say is: > > G 1 to 1 G > CTS 2 tie to 8 (plug) > TDXO 3 to 5 RXDO > DTR 4 to 6 DCD > RXDO 5 to 3 TDXO > DCD 6 to 4 DTR > G 7 to 7 G > RTS 8 tie to 2 (plug) > > Neither the 386 or 3b2 have DSR (RS232 pin 6) which is usually tied to > DTR. Is it needed? What you have is not recognisable by me. Here is my RS-232 memory jogger file. This may help some people. The Following are Various RS-232 Configurations. DB-25 25 Pin Std Connector Pin # 1 Ground (Protective Ground) (Optional) 2 Transmit Data (TXD) 3 Receive Data (RXD) 4 Request To Send (RTS) 5 Clear To Send (CTS) 6 Data Set Ready (DSR) 7 Ground (Signal Ground) 8 Data Carrier Detect (DCD) 9 + Testing Voltage 10 - Testing Voltage 11 No Connection 12 Speed Mode Indication (CI) 13 No Connection 14 No Connection 15 Transmit Clock 16 No Connection 17 Receive Clock 18 Make Busy/Analog Loop (CN) 19 No Connection 20 Data Terminal Ready (DTR) 21 Remote Digital Loop (RDL) 22 Ring Indicator (CE) 23 Speed Select - Originate (CH) 24 Clock Out 25 Test Mode (TM) DB-9 9 Pin Std Connector Pin # 1 Data Carrier Detect (DCD) 2 Receive Data (RXD) 3 Transmit Data (TXD) 4 Data Terminal Ready (DTR) 5 Ground (GND) 6 Data Set Ready (DSR) 7 Request To Send (RTS) 8 Clear To Send (CTS) 9 Ring Indicator (CE) (RI) DB9 to DB25 RS-232 Adaptor DB9 DB25 1 DCD 8 2 RXD 3 3 TXD 2 4 DTR 20 5 GND 7 6 DSR 6 7 RTS 4 8 CTS 5 9 RI 22 SHELL GND 1 Standard RS-232 Cable DB25 DB25 1 GND 1 2 TXD 2 3 RXD 3 4 RTS 4 5 CTS 5 6 DSR 6 7 GND 7 8 DCD 8 20 DTR 20 22 RING IND 22 (optional for answer modems) Minimum RS-232 Cable (OK for some slow devices) DB25 DB25 2 TXD 2 3 RXD 3 7 GND 7 Null Modem Simple (Using DB25 Connectors, see above for conversion to DB9) This Null Modem connector is equivelent to Black Box Model ME202B. It is used for conecting terminals to mainframes and UUCP connections. A B 1---------1 2---------3 3---------2 7---------7 4| 4| Note: | Means, pins are jumpered 5| 5| together. - means pins wired to other connector. 6| 6| 8| 8| 20| 20| Null Modem with control (With this cable, turning off a terminal should disconnect the line. recommended for use with terminals logged into mainframes.) A B 1---------1 2---------3 3---------2 4---------5 Note: | Means, pins are jumpered 5---------4 together. - means pins wired 7---------7 to other connector. 6|-------20 8| 20--------|6 |8 References: AT&T Unix-PC Communications Management Manual. Toshiba T1100P Users Manual EIA RS-232C (Oct 1969) Bell System Tech Ref Data Set 212A END -- Julian Macassey, n6are julian@bongo ucla-an!denwa!bongo!julian n6are@wb6ymh (Packet Radio) n6are.ampr.org [44.16.0.81] voice (213) 653-4495
mrb1@cbnewsh.ATT.COM (maurice.r.baker) (05/17/89)
In article <205@bongo.UUCP>, julian@bongo.UUCP (julian macassey) writes: > In article <433@bigbroth.UUCP>, rk@bigbroth.UUCP (rohan kelley) writes: > > I'm trying to make a direct connect between a bell tech 386/25 and > > a 3b2/400. The port on the 386 is an ace intelligent port board > > with 8 modular ports and on the 3b2 an enhanced port board. > > > > I'm trying to construct a modular null modem cable. This is the > > wiring diagram I've come up with, but haven't tried it yet. Does > > anybody know if this is correct? > > > > What I'm trying to say is: > > > > G 1 to 1 G > > CTS 2 tie to 8 (plug) > > TDXO 3 to 5 RXDO > > DTR 4 to 6 DCD > > RXDO 5 to 3 TDXO > > DCD 6 to 4 DTR > > G 7 to 7 G > > RTS 8 tie to 2 (plug) > > > > Neither the 386 or 3b2 have DSR (RS232 pin 6) which is usually tied to > > DTR. Is it needed? > > What you have is not recognisable by me. Here is my RS-232 memory jogger > file. > > This may help some people. > ( Handy listing of DB9 and DB25 pinouts deleted) It does not appear recognizable because both of these (ACE and 3B2) use 8-pin modular connectors........similar to the ones on a telephone cord, but with 8 pins. Besides being cheaper than DB-25 hardware (less labor intensive and material costs), they take up much less "real estate" in the machine or on I/O boards. A lot of RS-232 interfacing these days seems to be 3-wire "Hayes Smartmodem" kind of stuff anyhow, and they were able to boil 99% of all RS-232 interfacing down to 8 basic leads. DSR went by the wayside for modular plugs......according to the Bell Tech manual: "DSR is the modem equivalent of DTR. In common usage, it is redundant since modern modems are assumed to be functional when they are turned on". Likewise, RI was excluded in lieu of the Hayes-like response codes available for digestion in software. Now, I'm NOT saying that these RS-232 lines don't have any uses....quite the contrary, just sharing an explanation with you. Please don't flame me --- I miss them too, sometimes, when confined to the 8-pin modular connectors and/or I/O ports which ignore them! For the ACE side, here are the "official pinouts" (from the ACE manual): SHIELD 1 CTS 2 TXD 3 DTR 4 RXD 5 DCD 6 GND 7 RTS 8 For the 3B2 EPORTS side, the list is the same. (Incidentally, the 3B2 Expanded I/O board is identical, too, except that it does not support RTS/CTS). Reference sources are AT&T 3B2 Computer Enhanced Ports Manual, 305-441 ---and--- AT&T 3B2 Computer Expanded Input/Output Capability Manual, 305-530. When viewing the socket on the I/O board(s), pin numbering as indicated below: ^^^^^^ Pin 1 ---> ------ |: | |: --| |: --| |: | Pin 8 ---> ------ I thought that this information would be a useful addition to Julian's list of RS-232 interfacing facts. As to the original question, yes......it looks like your null modem cable should work fine. Don't forget the little "flying lead" with lug is protective ground (Pin 1) attached to the post on the 3B2 frame by each I/O jack. I suppose a precise interpretation of "Protective (Frame) Ground" in the RS-232 standard required AT&T to not rely on ground continuity through pin 1 and the I/O board connections into the mainframe. One thing to watch out for, though, when working with these little 8-pin beasties: there are 2 kinds of cables. Both have 8-pin modular plugs on the ends, but one variety has the pins wired identically (Pin 1 to 1, Pin 2 to 2, etc.) and the other has the pins flipped (Pin 1 to 8, Pin 2 to 7, and so forth). The former is known as a D8W distribution cord, and has uses in the telephone industry. The latter seems to be more commonly available (it's the kind Bell Tech includes with the ACE card, for example) and is meant for use with pre-assembled modular jack/DB-25 adaptors. From the ACE book again, here's the pinouts for these common adaptors: "Standard Terminal Adaptor" (Attaches to DTE) Modular DB-25 Female ------- ------------ SHIELD 1 SHIELD 1 CTS 2 RTS 4 TXD 3 RXD 3 DTR 4 DCD 8 RXD 5 TXD 2 DCD 6 DTR 20 GND 7 GND 7 RTS 8 CTS 5 ......................................................................... "Standard Modem Adaptor" (Attaches to DCE) Modular DB-25 Male ------- ---------- SHIELD 1 SHIELD 1 CTS 2 CTS 5 TXD 3 TXD 2 DTR 4 DTR 20 RXD 5 RXD 3 DCD 6 DCD 8 GND 7 GND 7 RTS 8 RTS 4 An easier way to make your null modem cable might be to conenct a terminal adaptor to a modem adaptor, and then plug in modular cables to the 3B2 and ACE cards. I might suggest including an inexpensive DB-25 equipped RS-232 LED "tester" in between the two adaptors ---- it's cheap (less than $10) and makes trouble-shooting much easier. Of course, a protocol analyzer at this point is the ultimate debugging tool, but costs a bit more :-) Our stockroom, for example, contains all sorts of externally-identical modular-to-DB25 adaptors (none marked in any distinguishable fashion). As always, the final test is to pop the thing open (screws or press fit) and see what's inside. A final question for all the net-readers out there: Who chose these pinouts? Why did the make these specific assignments? In particular, why didn't they make the physical placement symmetrical with the electrical signals (i.e., SHIELD/GND on 1/8, CTS/RTS on 2/7, TXD/RXD on 3/6, and DTR/DCD on 4/5 for example) so that a "flip cable" would act like a null modem and a D8W type cable would connect stuff 1:1 ??? Seems like that would have been really handy. Hope this helps with your RS-232 puzzles..............and I'll be watching for more discussion on the subject. M. Baker homxc!mrb1