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

  1. #1
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    Default Cannot connect Linux to VAXstation 4000/90 (cougar) via RS-232

    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!

  2. #2

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    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.

  3. #3
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    Default

    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?

  4. #4
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    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!

  5. #5

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    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.

  6. #6
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    Quote Originally Posted by blabsxar View Post
    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 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...odular-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).
    Last edited by AK6DN; January 9th, 2018 at 11:05 PM.

  7. #7

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    Quote Originally Posted by AK6DN View Post
    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.
    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)

  8. #8
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    Quote Originally Posted by AK6DN View Post
    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...odular-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).
    Thats about right. The install manual is here:-

    http://manx-docs.org/collections/mds...x/vaxoginb.pdf

    and you do need an mmj connector...
    Dave
    G4UGM

    Looking for Analog Computers, Drum Plotters, and Graphics Terminals

  9. #9
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    Quote Originally Posted by cruff View Post
    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)
    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.
    which is kind of confusing as well...
    Last edited by blabsxar; January 10th, 2018 at 10:52 AM.

  10. #10
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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).

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