RE: Control of ventilation system

["Hawes,Timothy Edward \(GEG\)" <haweste@xxxxxxxxxxxxxxx>]

Hi Martin,

It's not a very elegant solution, but one that may work and avoid you
having to interpret the signals on the connection cable. Hack the
supplied keypad and replace (or wire-out) the push-buttons with relay
contacts. You then connect the coil part of each relay to an output of
the Logo/Web Brick/NetIOM etc. so that energising the relay closes the
contact and the ventilation control panel thinks you've pushed the
button with your finger.

If you can wire out the push-button contacts and still keep the
faceplate intact then you get the best of both worlds - local control
*and* an automation interface. If you can't keep both, maybe you could
make your own local faceplate with push-buttons and use those as inputs
to your new controller so you don't lose the local controls.

The other alternative is to completely scrap the controls provided with
the unit and build your own interface to control the motors, fans etc. I
might be inclined to hack the control panel buttons before attempting
this one though :-)

HTH,

Tim.


> -----Original Message-----
> From: Martin Howell
>
> Hi Tim,
>
> Thanks for the offer.  The unit has a hard wired control
> panel, connected via 4 core cable to the control PCB inside
> the main housing.
> The only diagram I have shows the connections as:-  +12v;
> GND; HI; LO, and I don't have a circuit diagram of the main
> system board.  The control panel has buttons to
> increase/decrease the fan speed and temperature, and some
> sealed electronics which I can't get to, which I presume send
> an encoded signal along the HI/LO connections when the
> buttons are pressed.  The only thing I can think of at the
> moment is to put a scope on the signal connections and see
> what is going on, but i was hoping someone else had already
> done it, lazy sod that I am  :-)
>
> Martin