Pdp11/93 rs232 pinouts

[Roe]

Does anyone have pin descriptions for the 9-pin DB-style RS232 connectors on a pdp11/93 rear bulkhead unit? It's got one standard DB-25 for the console, 7 (I know this is the wrong term) DB-9 male connectors (for the rest of the simulated DL-11s), a two-digit LED display, and a dipswitch for baud rate on the console port.

Before I start with the multimeter, can anyone point me at a pinout of these DB9s?

Thanks.

 

[nigwil]

The DB-25 is the console port, and I expect a DTE pinout (I don't recall it being anything surprising, I connected a terminal and it worked). The other ports are DE-9's and usual DEC pinout for that style.

http://www.pdp-11.nl/pdp11-93startpage.html

 

[Roe]

And what is the usual DEC pinout for a DE9 connector?

 

[Uniballer]

I can't think of anyplace else DEC used DE9 connectors (because of the connector-conspiracy-driven MMJ debacle). Pin 5 is signal ground. TxD is either pin 2 or 3 (use your voltmeter to find out: it will be at a negative voltage relative to signal ground). RxD is also either pin 2 or 3 (i.e. the one not being driven).

Link to PC pinouts for these connectors, but DEC might be reversed...

 

[cruff]

I made a cable to connect my 11/73 in a BA23 (that formerly held a VAXstation 3200) to a VT220, it has a DE9 on the VAX console bulkhead. It is wired like so:

[FONT=Courier New]DE9    DB25
2 ----- 3
3 ----- 2
7 ----- 7
        4-5
        6-8-20
8-9
[/FONT]

 

[Roe]

I made a cable to connect my 11/73 in a BA23 (that formerly held a VAXstation 3200) to a VT220, it has a DE9 on the VAX console bulkhead. It is wired like so:

[FONT=Courier New]DE9    DB25
2 ----- 3
3 ----- 2
6 ----- 7
        4-5
        6-8-20
8-9
[/FONT]

Are you sure about the pin 6->7 connection? I found docs for a microvax port, it indicates pin 5 is ground...

 

[gslick]

Are you sure about the pin 6->7 connection? I found docs for a microvax port, it indicates pin 5 is ground...

http://www.bitsavers.org/pdf/dec/vax/630/MP02071_630QB_Mar85.pdf

Page 85 of the PDF, KA630 Function Select / SLU Module schematic.

Pin 1 - Chassis Ground
Pin 2 - SLU Output / Transmit Data
Pin 3 - SLU Input / Receive Data
Pin 4 - no connection
Pin 5 - +12V Fused (through a 750 ohm series resistor)
Pin 6 - no connection
Pin 7 - Signal Ground (through a 100 ohm series resistor shared with Pin 8)
Pin 8 - Signal Ground (through a 100 ohm series resistor shared with Pin 7)
Pin 9 - no connection

I haven't verified myself that the 11/93 bulkhead panel uses the same pinout for its DB9 connectors.

 

[gslick]

I just took a look at a 70-27975-01 11/93 SLU panel that I have and these are the pinouts that I found.

SLU 1 - SLU 7 - DB9
Pin 1 - Chassis Ground
Pin 2 - SLU Output / Transmit Data
Pin 3 - SLU Input / Receive Data+
Pin 7 - Signal Ground
All other pins No Connection

Console - DB25
Pin 1 - Chassis Ground
Pin 2 - SLU Output / Transmit Data
Pin 3 - SLU Input / Receive Data+
Pin 4 - connected to Pin 6
Pin 6 - connected to Pin 4
Pin 7 - Signal Ground
Pin 20 - +12V Fused (through a 750 ohm series resistor)
All other pins No Connection

All of the Receive Data- signals (J1-7, J1-17, J1-27, J1-37, J2-27, J2-37, J2-47, J2-57) are connected to Signal Ground.

There is a P6KE15CA TransZorb transient voltage suppressor between each TD and RD+ signal and Signal Ground, plus another one between Signal Ground and Chassis Ground (17 of those total).

 

[cruff]

Are you sure about the pin 6->7 connection? I found docs for a microvax port, it indicates pin 5 is ground...

Just looked again, it is on pin 7, not 6.