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Cannot connect Linux to VAXstation 4000/90 (cougar) via RS-232

B

blabsxar

Member
Joined
May 9, 2017
Messages
11
Location
Sao Paulo, Brazil
Hi!

I recently got a beautiful and likely functional VAXstation 4000/90 (cougar). When I turn it, leds turn on and off and it makes a beautiful sound at the end of the initialization process. It then turns off all leds, hence indicating no error. Although everything seems fine, I cannot show the console prompt connecting a Linux machine to the VAX. I rechecked configuration:

S3 switch is at the console position (up), a null modem cable is connected between Linux machine and the VAX. I have already tested the cable between one Linux and one BSD machine and it looks fine. I'm trying to connect to the machine using command:

Code: 
cu -l /dev/ttyS0 9600

This is *exactly* the command I'm using to connect to the BSD machine. The VAXstation 4000/90 manual says the baudrate is 9600 and that is what I'm using. Unfortunatelly, there doesn't seem to exist any other indicator to tell me if I'm having any problem with my configuration.

Do you have a clue?

Thanks!
 
I've connected to my 4000/60 from macOS using a Keyspan USA-19HS USB to serial adapter and a suitable cable, which of course, I can't find right at the moment. I'll try to dig it up and report on the details.
 
I use a DEC H8571-J and a MMJ cable (crimped myself, standard rollover). Works fine with `minicom` under Linux and `cu` under OpenBSD. I've used it with ISA/PCI/PCIe RS-232 ports as well as a no-name USB -> RS-232 cable with a Prolific chip inside.

What are you using to go from RS-232 to MMJ?
 
I'm actually connecting to the DB25 plug. I use a standard serial cable that I cut to make it cross-over (null modem). It works pretty fine if I use it between two Linux machines. The DB25/DB9 adapter also works because I tested it with a VT520 terminal. A picture of the cable I'm using follows:

c.jpg

After talking to the guy who sold me (who told me everything was working fine) showed a picture of the cable he was using:

index.jpg

Can it be a totally different cable? Is it non-standard? What's the difference between the MMJ connector and the DB25?

Thanks!
 
I can connect using a MMJ cable, the H8571-B (J?), a null modem adapter and my USA-19HS attached to my Mac at 9600 baud, no parity using Kermit.
 
blabsxar said:
I'm actually connecting to the DB25 plug. I use a standard serial cable that I cut to make it cross-over (null modem). It works pretty fine if I use it between two Linux machines. The DB25/DB9 adapter also works because I tested it with a VT520 terminal. A picture of the cable I'm using follows:

View attachment 42928

After talking to the guy who sold me (who told me everything was working fine) showed a picture of the cable he was using:

View attachment 42929

Can it be a totally different cable? Is it non-standard? What's the difference between the MMJ connector and the DB25?

Thanks!
Click to expand...

I believe the RS232 console can ONLY be accessed thru the rear panel MMJ port when the enable switch on the front panel is in the UP position.

The DB25 port is a different port (for a printer) and is not wired into the console. So you need a DEC MMJ serial cable (looks like an RJ11 phone connector, but not the same) to DB9, etc cable.

I use this: https://www.stonewallcable.com/bc16e-eq-dec-cable plus one of these: https://www.stonewallcable.com/h8571-j-eq-dec-modular-adapter

which are basically DEC BC16E cable and a DEC H8571-J adapter. You might find actual DEC parts on Ebay (I searched and found some, but they wanted more $$ than buying from Stonewall).
 
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AK6DN said:
I believe the RS232 console can ONLY be accessed thru the rear panel MMJ port when the enable switch on the front panel is in the UP position.
Click to expand...

This is correct, the manual for the 4000/60 is quite clear that the rear MMJ port is the alternate console port, which is not connected to the DB25 port in any way. Confusingly they are named:

MMJ: Printer/Communications port (TTA3: in VMS)
DB25: Communications/Printer port (TTA2: in VMS)
 
AK6DN said:
I believe the RS232 console can ONLY be accessed thru the rear panel MMJ port when the enable switch on the front panel is in the UP position.

The DB25 port is a different port (for a printer) and is not wired into the console. So you need a DEC MMJ serial cable (looks like an RJ11 phone connector, but not the same) to DB9, etc cable.

I use this: https://www.stonewallcable.com/bc16e-eq-dec-cable plus one of these: https://www.stonewallcable.com/h8571-j-eq-dec-modular-adapter

which are basically DEC BC16E cable and a DEC H8571-J adapter. You might find actual DEC parts on Ebay (I searched and found some, but they wanted more $$ than buying from Stonewall).
Click to expand...

Thats about right. The install manual is here:-

http://manx-docs.org/collections/mds-199909/cd1/vax/vaxoginb.pdf

and you do need an mmj connector...
 
cruff said:
This is correct, the manual for the 4000/60 is quite clear that the rear MMJ port is the alternate console port, which is not connected to the DB25 port in any way. Confusingly they are named:

MMJ: Printer/Communications port (TTA3: in VMS)
DB25: Communications/Printer port (TTA2: in VMS)
Click to expand...

You are right, guys. The guy who sold me the equipment was also wrong. He rechecked and he was connecting the machine with a DEC terminal with a MMJ-MMJ cable. I'm going to take one with him today's afternoon and see if it works.

The manual also says about the DB25 port:

Used primarily to connect an
asynchronous communications
device such as a modem,
through an RS232 cable. The
secondary use is to attach a
printer or hardcopy terminal.
Click to expand...

which is kind of confusing as well...
 
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As stated above, yup, that's your problem :) I've got the crimp die and ends for making MMJ cables, but it looks like there's a link for premade ones. I don't know if I have any spare MMJ -> RS-232 adapters. You can make your own, there are a few resistors you need to go from MMJ to RS-232 (IIRC, MMJ is a differential arrangement).
 
Hi!

That was the problem: it worked pretty fine after I used the MMJ cable to connect to a VT 520 terminal (which also has a MMJ port). Why wouldn't DEC just have a DB9 or DB25 for serial communication? To force people use their own proprietary stuff?

Also, do you have details on the MMJ to RS-232 conversion? A quick search for "MMJ DB9 pinout" on the web shows me simple diagrams. A page that has some information is this: https://www.lammertbies.nl/comm/cable/dec-mmj.html

Thanks again, guys.
 
AK6DN said:
I use this: https://www.stonewallcable.com/bc16e-eq-dec-cable plus one of these: https://www.stonewallcable.com/h8571-j-eq-dec-modular-adapter

which are basically DEC BC16E cable and a DEC H8571-J adapter. You might find actual DEC parts on Ebay (I searched and found some, but they wanted more $$ than buying from Stonewall).
Click to expand...

The MMJ adapters are one of those things that can be expensive when you need one and cheap when you don't. I was watching some original DEC H8571-A adapters on eBay for a long time with no takers before I finally grabbed 8 of them for around $3.50 each, including shipping. Most of them still in original sealed bags. These are 25-pin female connectors. Not always what I need, but I have plenty of 25-pin / 9-pin adapters and gender changers if I need something else. I have a 16 MMJ port DECserver 300. Too bad I don't have 16 VT100s to hook up to it. :)
 
gslick said:
What crimp tool and die set do you use? I wouldn't mind being able to make up my own MMJ cables on demand when necessary.
Click to expand...

Paladin Crimpall 8000 frame, Paladin 2067 "DEC-MMJ" die. Excellent frame, lots of die options. They show up used on popular auction sites for a good price fairly often.
 
gslick said:
DEC H8220 is a package of 50 DEC MMJ connectors. Those still seem to be available from a few places.
Click to expand...
I don't know if they're the least expensive, but I got a bag of 50 of those at https://www.ebay.com/itm/262227271837?_trksid=p11400.c100710.m-1&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D41050%26meid%3D61b8ab0fbdc34ec9b7d08a085441c1e4%26pid%3D100710%26rk%3D2%26rkt%3D2%26sd%3D162291819594&ul_noapp=true . Quality is good, and the plastic in them has not yet become brittle.

DEC H8240 (17-00721-01) is a 1000-foot spool of 6 conductor flat BC16E cable. Anyone have a source for that if you wanted to build cables with original DEC branded cable?
Click to expand...
I ordered a spool of this https://www.ebay.com/itm/1-000-ft-Spool-6-Conductor-26-Gauge-Flat-Cable/162291819594?hash=item25c958a44a:g:-L0AAOSwiONYNMbh back in April, 2017 with hopes that it would work OK for making up MMJ cables. It works great for that, but I was shocked to find the spool is actually labeled as being from Digital Equipment Corp.
 
zamp said:
I ordered a spool of this https://www.ebay.com/itm/1-000-ft-Spool-6-Conductor-26-Gauge-Flat-Cable/162291819594?hash=item25c958a44a:g:-L0AAOSwiONYNMbh back in April, 2017 with hopes that it would work OK for making up MMJ cables. It works great for that, but I was shocked to find the spool is actually labeled as being from Digital Equipment Corp.
Click to expand...

Is the cable labeled as DECconnect cable on the itself? Or was the Digital Equipment Corp label on the spool or on a tag? In the listing photo I just see the SPECTRA STRIP tag and don't see any printing on the cable itself.

With that listing for 1000-feet at $85 shipped that would work out to around $1 for a 10-foot cable. That's not so bad if you plan on making a lot of them.
 
gslick said:
Is the cable labeled as DECconnect cable on the itself? Or was the Digital Equipment Corp label on the spool or on a tag? In the listing photo I just see the SPECTRA STRIP tag and don't see any printing on the cable itself.
Click to expand...
I just dug out the spool and took a picture:
spool.jpg
The lower two labels are ones I applied (yes, I act a little OCD pretty often). The top one is what came on the spool and reads "DIGITAL EQUIPMENT CORP. H8240 QTY: 1 DATE 5191". That's the exact part number you were looking for.

There was only one thing off about the order. The spool I received looked exactly like the one in the eBay auction, including the dirty, off-white tape that is applied around the spool to hold on that yellow tag. And it seemed to have been applied a long time ago and over time exuded some messy goo on a few turns of the outer layer of cable. I pulled that nasty tape off and used some Goo Gone to clean up the outer layer (again, OCD?). But other buyers can do whatever they like about that slight mess, including trying to ignore it.
 
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