modular null modem pinout?
julian macassey
julian at bongo.UUCP
Tue May 16 12:11:34 AEST 1989
In article <433 at bigbroth.UUCP>, rk at 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 at bongo ucla-an!denwa!bongo!julian
n6are at wb6ymh (Packet Radio) n6are.ampr.org [44.16.0.81] voice (213) 653-4495
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