HOME › Forums › Input/Output › EZIOxx › EZIO2X4 – How to use I3/I4 as simple "dry contacts"

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  • Anonymous
    Inactive
    December 18, 2012 at 6:24 pm
    Post count: 31
    #40355

    Hi everyone,

    I’m a programmer with a minimal electrical theory background. I’ve read several posts here that all give me some clues as to how to use these inputs as a simple “dry contact” switch but I’m just not getting it. Can someone explain exact wiring to make this happen reliably? Do I need a pullup resistor in this case? For discussion purposes, assume I have a simple switch that is closing/opening the circuit.

    Thanks!
    Daniel

    Anonymous
    Inactive
    December 18, 2012 at 8:15 pm
    Post count: 192
    #43924

    Yes a pull up would be needed.
    Connect a 10,000 Ohm 1/4 Watt resistor from I3 to +5 volts and a 10,000 Ohm 1/4 watt resistor from I4 to +5.
    Then connect the dry contact switch from I3 and Ground and the other dry contact switch from I4 and Ground.

    A 4,700 Ohm resistor would also be fine for the pull up resistors.

    Anonymous
    Inactive
    December 19, 2012 at 5:01 pm
    Post count: 31
    #43925

    Thanks for the explanation, BLH! Makes sense. So really, any reasonably high resistor (>4k) should provided the needed resistance to do the job here? That’s how I’m interpreting this.

    Anonymous
    Inactive
    December 19, 2012 at 5:48 pm
    Post count: 192
    #43926

    4.7K maybe a good choice. Is about a 1 mA load on the five volt supply rated at 20 mA and isn’t so high a real long wire length would effect how low it went when the contacts are closed.

    Anonymous
    Inactive
    December 20, 2012 at 7:08 pm
    Post count: 31
    #43927

    Thanks BLH. I didn’t see your message until today and ended up buying some 10K resistors while out yesterday. They did the trick. Do you see this size of resistor causing trouble with I3/I4 and a dry contact at the end of a ~500′ 18 guage wire run? (i.e. ~1000′ total wire to and from the end point).

    Anonymous
    Inactive
    December 20, 2012 at 8:14 pm
    Post count: 192
    #43928

    1000′ of #18 stranded copper wire. Is about 6.51 Ohms and solid #18 is 6.39 Ohms on a chart I found.
    No problem.

    Anonymous
    Inactive
    December 20, 2012 at 8:48 pm
    Post count: 31
    #43929

    Excellent, thank you for clarifying that!

    In the event that anyone from SHN is watching this thread:

    I believe I understand enough about this to see why I have to manually install the resistors “out in the field” (i.e. it preserves maximum control for me between the contradictions of analog vs. digital operation on these inputs). I really think you should at least include and ship the 2 resistors with the product. I don’t keep a stock of resistors on hand and had to go to town to pick them up. Meanwhile (prior to installing them), the constant INSTEON network chatter on IN3/IN4 opening and closing was enough to cause serious issues on my network that is otherwise noise-free and flawless. I even had cases where the EZIO itself appeared to “disappear” and magically do things on its own (i.e. output 1 on, etc.). 🙁

    Things appear to be working great now…

    Anonymous
    Inactive
    December 20, 2012 at 9:09 pm
    Post count: 192
    #43930

    Since the I3/I4 inputs can be set to analog. They have no pull up resistors on them. So an internal one is not in the design.
    I have seen posts indicating if you do not use I3/I4 to wire them to the ground pin to prevent the chatter and constant Insteon broadcasts.
    Folks using an ISY controller would also see constant chatter if the Analog/Digital Inputs of any EZIO model with them left them floating.

    Anonymous
    Inactive
    December 20, 2012 at 9:43 pm
    Post count: 31
    #43931

    Good point on the ground connection, I did come across that at one point.

    Anonymous
    Inactive
    June 21, 2013 at 4:50 pm
    Post count: 31
    #43932

    I’m the original poster of this thread and I’m back with a new but very related question… I’m enabling my first analog sensor on I4 (ATS2000a temperature sensor). I connected it per the diagram to I4 and I removed the pull-up resistor I previously had on the input (to keep it from bouncing around when it was unused). Everything works perfectly and I’m reading accurate temperatures. The problem is that I have a simple dry contact device connected to I3 per the method described in this thread. Even with the pullup resistor on I3, it’s bouncing around because *both* I3 and I4 are switched into analog mode. Is there a recommended approach that I can use to keep I3 functioning like a dry contact when I3/I4 are enabled as analog inputs?

    Anonymous
    Inactive
    June 21, 2013 at 5:08 pm
    Post count: 31
    #43933

    In other words, when an analog input is running in analog mode is there a way to tune the alarm settings so that it effectively behaves like a digital input?

    Anonymous
    Inactive
    June 21, 2013 at 9:02 pm
    Post count: 1001
    #43934

    The default value of 0 for both trip points is likely the cause. Adjust the trip points so that neither is at the actual On or Off values. The trip points should be values that occur as the analog input voltage is moving from On to Off and Off to On, not at the either point. Also remember that in digital mode GND is On. In analog mode GND is Off so the trip point for On to Off should not be 0. Perhaps the On to Off would be 20 and the Off to On would be 100. The Off to On value depends on the voltage applied by the pullup resister . The Off to On trip point should be below the value established by the pullup resister. .

    Anonymous
    Inactive
    June 21, 2013 at 9:35 pm
    Post count: 31
    #43935

    Thanks for the response and helpful info!

    With I3/I4 in analog mode and otherwise factory defaults (0 for both alarm trip points), I did a query on AN1 to peek the analog value of the input that has a dry contact attached to it with the pullup resister in place. The analog value queries as 1023. Based on what you said about GND being Off in analog mode, would this suggest that my contact is currently open?

    Anonymous
    Inactive
    June 21, 2013 at 11:18 pm
    Post count: 1001
    #43936

    Yes

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