PLC for home automation?

[Ken Moore]

You could use the second pole to make the two coils toggle and be energized on every other pulse. However, you also need a "one shot" feature, other wise unless you are very fast, the relay will cycle several times before you release the push button.

Your best bet may be to use some sort of hand-off-auto arrangement.

 

[elevmike]

Another note:

Antor,

If you use the scheme I described in my previous post, this will allow you to use the room switch to force the lights off regardless of the PLC & Occupancy Sesnor. In most cases this will suffice, as the PLC will turn off the lights by energizing the relay coil, and turn on the lights by dropping the relay coil. So if the relay coil is off due to a PLC or panel failure the lights will go ON, and the switch would be used to force them OFF. When the PLC resumes operation, the lights will remain off until you place the room switch to the off position.

Like is said, in most cases this is exactly what the owner wants, because it will allow him to trun the lights off regardless of occupancy. However this requires an ON/OFF switch, (not a momentary button).

 

[WireGuy1950]

I am attaching a couple of PDF's on single coil bistable relay you could use to energize your power relays.

 

[raviv]

Long time no update!

Well... the good news is that I am almost finally done. I've gone with the equipment above and programmed a very flexible rules engine in C++ that runs in the DL205. In essence, it understands wall switches, pushdowns, presence detectors, etc. as inputs and can operate a variety of outputs, at this point all connected via relays and then to light bulbs.

I'll will post a pic of the work-in-progress area in which all fuses, relays, PLC, etc. are installed to give you an idea of the size of the installation.

I have one question though: although I've stress-tested the DL205 program I've written, I still want to be able to operate the house even if the PLC fails, crashes or is simply dead.

I've decided to install pushdown buttons instead of switches in the walls, each time you press the pushdown button, the PLC detects the pulse and acts accordingly (e.g. sending 24 VDC to the appropriate relay). The problem with this approach is that I cannot connect the pushdown buttons to the relays directly should the PLC be dead, as the relays are not latching relays.

So the question is:

1. Do you know of any good AND SMALL latching relay (operated by a pulse, not continous 24 VDC volt.)? I went with the RS6N-DE 6-in-a-card relays as the densitity of relays per space is pretty good.

2. Do you know of a simple, high density (64 ins and 64 outs; or 32 ins and 32 outs) DIN mounted device that can translate 24 VDC pulses into 24 VDC states? That would be a simple way of simulating a latching relay putting this device before the relay coils.

What I am trying to achieve is a way of being able to use pushdown buttons (that output a 24 VDC pulse when pressed) to control the lights-switching relays.

Thank you in advance!

STEP RELAY