Re: Control of ventilation system

[Martin Howell <martin.howell@xxxxxxxxxxxx>]

Hi Tim,

Good plan, I'm certainly not averse to a bit of hacking if that's the
only solution, they are membrane buttons and shouldn't be too hard to
connect up to.  The complete DIY approach is probably a non starter as
the system does have some sensors and other stuff to monitor excessively
low temps; blocked filters and overheating, so I would lose them if I
went down this route.  I will probably try putting the silly-scope on
the signal cables, it may be easier than it seems!  Thanks again

Martin

Hawes,Timothy Edward (GEG) wrote:

>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
>>
>>
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