help with simple interface circuit

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- johanwagener
  
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posted
17 years ago

Wed, Mar 28, 2007 6:45 AM

I have the following scenario. I have to do an automated blinds installation. The control circuit for the blinds consists of the following: A microcontroller which switches on two relays for up and down, a single motor does the up and down. Two limit switches input to the micro to prevent the rail from moving too far. The actual control consist of 3 buttons. Which supplies three 12vdc signals back to the microcontroller. Up, Down and Stop.

The problem I am having is that I need to integrate this into my homeautomation device. It is a dynalite relay module. From which I normally use two relays. One for up and one for down. Usually the blinds I use only has neutral, a live for up and a live for down. So the cabling have been done already. I've only got 3 wires running to the blinds and I need to make this control circuit run with this.

Any suggestions for a circuit?

I've been thinking of using a relay which is wired common to 12V normally closed to stop and normally open to up and then another relay (or a double pole) with the common to 12V, normally closed to stop and normally open to down.

The only problem I can see is that the stop signal will be sent to the micro the whole time.

Otherwise I am going to have to reprogram the micro. It is an MDT and I don't carry any knowledge that type.

Thank you

Johan

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- petrus bitbyter
  
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posted
17 years ago

Wed, Mar 28, 2007 6:32 PM

schreef in bericht news: snipped-for-privacy@n59g2000hsh.googlegroups.com...

Guess that micro has nothing else to do but polling that UP/DOWN/STOP switches. So if it sees "STOP" most of the time, who cares? The micro will check whether the motor has been stopped and continue its polling. It will not get tired or complain.

If you realy want to simulate the original buttons, you can do so using a spdt and a dpdt relais. See below. Named them X and Y respectively. (Only the contacts drawn, use fixed font.)

|+12V | | | o \ x \ o \o | | +-------+ | | | | +-+ | | | | o o \ y1 \ y2 \ \ o \o o \o | | | | | | | | | | | | | | | | Stop Down Up

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petrus bitbyter

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- ehsjr
  
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posted
17 years ago

Thu, Mar 29, 2007 2:41 AM

You have 3 wires to the blind operating motor. Go simple. Lose the ucontroller, use the limit switches to stop the motor, and do this:

+12 -------+-------------------------+ | | +---o o---+ \ RY1-1 o---[Motor]---o RY1-2 \ +---o o---+ | | Gnd -------+-------------------------+ | Dynalite +12 --------[RY1]-----------+

When your automation controller tells the blinds to open, the dynalite relay will energize RY1, which is installed at the blinds motor location, and the blinds will open. The limit switch will stop the motor. When the automation controller tells the blinds to close, the dynalite will drop the +12 on the line, so RY1 will drop and the blinds will close. The other limit switch will stop the motor.

If the ucontroller is physically located at the motor location, you already have power there. If the power is there and you have thre additional wires for control, just ignore the stop line, and run the dynalite signal to a relay. Use the N/O & N/C points of the relay for close and open. Again, the limit switchs stop the motor.

If you really want to complicate your life, use your automation controller to select several different relays, each of which selects a different tap on a voltage divider, and send that voltage on one wire to the blinds assembly. Detect the voltage and use it to determine how far to open the blinds.

Ed