[plug] [OT] Maitec Linx UPS Serial Interface

[Ryan]

On Sat, 2005-02-05 at 12:34 +1000, Rider Hunt - Sunshine Coast wrote:
> Hello
>  
> We have an old Maitec Linx 1400 VA UPS (but still operational) which
> has a serial peripheral interface port which we have not used for some
> years. We believe your company has done work on it in the past.

We are a Linux Users' Group based in Perth, however you are correct,
there has been some discussion on this list about it :)

For anyone angry at the OT, these UPS units are brilliant old Australian
made beasts, and I have about 6 Debian servers plugged into 2 of them -
near enough? :)  I still haven't managed to interface them however - I
lost interest in that a long time ago :(

> We are now setting up a new system and it is my desire to interface
> the UPS with the server to enable an orderly shutdown in the event of
> a power failure.

My last correspondence regarding these from several sources indicated
the serial port is for interfacing relay I/O and not for RS-232
communications.

A tentative pin-out I received:

Pin2 Mains Fail N/O Contact
Pin1 Mains Fail N/C Contact
Pin3 Alarm N/O Contact
Pin6 Alarm N/C Contact
Pin 7 Alarm Common Contact
Pin4 Linx ShutDown Input
Pin9 Linx ShutOn  Input
Pin 8/5 Not Connected

Someone then provided me these ideas:

=====================================

Therefore:
    N/O Contact means Normally Open Switch Circuit from that pin to the
Common.
    N/C means Normally Closed Switch.

So Pin1 to 7 would normally be a short circuit when the Mains has
failed. Alternatively Pin2 to 7 would normally be a open circuit when
the Mains has failed.

If one therefore wrote to Pin1 and read from Pin7 the values would match
when the Mains failed; and not match othwerwise.

To test this all one needs is a multi meter to check the pin to pin
connectivity in the various operational states.

To test pins 4 and 9 it is a matter of writing to the pins (maximum
voltage according to the sheet is 3.5V) with a pulse of 300ms minimum
duration. I don't image however that you wish to turn it off from inside
software; a bit like pulling one's own power point out.

=====================================

I have an 800 and 1400 Linx (http://gallery.slowest.net/maitec-linx),
but have not tried any of the above.  The people who reported this
obtained a circuit diagram for a 500 and 1000 Linx.  Providing they
maintained this configuration it should apply to all 1500 models and
below. 

With regards to software/hardware setup for the above, I'm assuming
you'd have to roll-your-own to monitor the serial ports, however someone
else on the list will have more of a clue than me in this area.  There
are messages in the PLUG archive you have probably seen with nice PIC
based ideas and pretty ASCII art explaining it :)
(http://www.cantech.net.au/plug/2002-10/msg00606.html)

I have also seen previously (on a page that is now dead) a command set
from Linx units.  It appeared that there was some kind of terminal
server card available with a serial interface.  You could login to the
unit and issue commands.  If you are game, chuck a serial cable on and
have a play with minicom/hyperterminal via a serial port you don't
highly value - you never know what you might find :)  I think such cards
were for 3000+ series, but all models have modular card slots and might
accept such a card.

These (http://www.alandelectronics.com.au/) folk in Queensland also
reportedly service Maitec units, so they'll probably have _some_ idea
how they work.

HTH,

Ryan