Ive attached a normal PIR motion sensor to a URC contact sensor. One would think when motion sensed, the contact closure on the motion sensors opens, the URC sensor detects this, thus executing the macro. Not so.

If i unplug the URC sensor, my meter clearly shows me the motion sensor is working: no motion = closed circuit. motion = open circuit. Perfect. Just as it should. If i plug URC sensor in, the state is ALWAYS open.

Turns out the URC contact sensor outputs 5.6v ! This apparently is mucking up the contact sensor in the motion sensor. Think I on the right track here lol.

So, what I need to do is add some resistors or something to the URC sensor to stop the 5+volts from going back to the motion sensor. I have no idea what that formula is or what parts are needed.

Figured this was up Ernie's ally lol. Ideas?

Can’t you just put a diode in?

Is the PIR an actual relay contact or a semiconductor switch?

Buzz has got it.
The URC is suppose to put out a voltage, that is the trigger when a contact opens or closes for the URC to see. The motion sensor you have chosen does not have the proper contacts for you to use (by the sound of it).

So you asked for it, here is the Ernie reply: What make and model motion sensor are you using!!! Doh...

You need a dry contact PIR or we can figure out a way to incorporate relay triggered by PIR and then C. and N.O. or N.C. contacts would tie into your URC.
Your choice.

Right. I cannot figure out from your description what the HELL components you are talking about. For instance, the motion sensors I'm aware of are dry contacts that can be wired as open until sensing (NO = normally open, or NC = normally closed) or closed until sensing. You'd wire power from a supply through that relay and on to the next thing... which is a contact sensor? What's a contact sensor? Do you mean a URC SEN-CCLS Contact Closure Sensor?

A contact closure sensor would output a voltage, just as yours does. It would sense when this voltage has been shorted by a motion sensor. It might be able to be set up to detect the relay closing, or the relay opening. The normal method would be to have the motion sensor close its dry contacts.

Mario neatly sidestepped the brand and model issue by describing what you should be using but offering no details.

3p, It was suggested by a fellow URC'r to add a 1amp diode between the URC sensor and motion sensor. That would stop the voltage from going back to the motion sensor. No idea if that will work but thats what I am going to try first.

Yes Ernie, its a URC SEN-CCLS Contact Closure Sensor.

The sensor is just a normal Bosch PIR. No idea if its a relay contact or a semiconductor switch, Buzz. I will have to find the part number.

I figured if a security panel can sense if the contact closure on a motion sensor, the URC sensor would as well. Nope.

The diode is a whopping 29 cents. Worth trying. We'll see if I can smell smoke lol.

You're not understanding what these components do.

On Page 1 of the SEN-CCLS manual, it says

This is what we have been talking about.

So how does it do that? The SEN-CCLS outputs a voltage. THAT'S HOW IT DOES WHAT IT DOES.

That voltage is applied to a set of dry contacts. In civilian terms, a set of dry contacts is a switch. So the voltage goes to a switch. When the switch is thrown, the SEN-CCLS gives an output. It can be set up to do something when the switch closes (NO) or when the switch opens (NC).

It's up to you to determine if this output is something you can use to do what you want.

What you don't want to do is to put a diode into this circuit anywhere.


A semiconductor switch is more expensive than a relay, so I'm going to guess there's a relay in that unit.


Yes, it will, but it does so by sending a voltage to the contacts. You're thinking it does something else.

Read the manuals of the different stuff you have and you'll be able to figure out how to wire this.

Was thinking you would give me a fish instead of teaching me to fish lol.

A contact sense port will put out a current limited voltage (probably using a series resistor) and this voltage will collapse to zero when a sensed relay contact is closed.

You can use a high impedance Voltmeter to measure the sense voltage because the series resistor is essentially zero compared to the Voltmeter's high input impedance (implying no current and zero voltage drop across the series resistor). If you use a low impedance (cheap) Voltmeter, there may be enough current to result in a voltage drop across that series resistor -- resulting in a lower Voltage indication than when using the high impedance meter.

A "semiconductor switch" could be a simple transistor. While this is significantly cheaper than a relay, there are certain disadvantages: First, this transistor is polarity sensitive. If the contact sense voltage is the wrong polarity, the transistor will not switch ON. One could work around this (for a range of voltages) with some clever biasing techniques. Second, the series resistor used to protect the "relay" transistor, will result in a voltage drop that may frustrate a sense device that is expecting a voltage closer to zero. Third, the junction voltage of the transistor may not be close enough to zero to satisfy the contact sense input.

The PIR could also use a "Solid State Relay" (these cost well under a dollar in quantity). Solid State Relays (you may also find these described as "Solid State Switch") are not polarity sensitive, but similar to the transistor, there is a "junction voltage" that might frustrate the contact sense input.

---

Inserting a diode in this circuit will make things worse. If the sense voltage is DC and the diode is inserted in the wrong direction, there will be no current. In the other direction the diode junction voltage drop will set the minimum voltage to be sensed by the port. If the PIR uses a solid state switch, the junction voltages will sum and establish a higher sense voltage for the port to deal with.

All the answers are here except those to be gotten by reading the PIR manual. So why is it that people have an attitude when I ask for model numbers? That's all that's missing from doing Ranger Home's work for him.

The posts I've seen from Ranger Home in the past tell me he knows how to figure this out.

I'm flying mostly blind, but here is the outline of a scheme to try. I'm assuming that the PIR uses a semiconductor switch, but the observation in the first post that you could observe the PIR switching with a multimeter makes me wonder because I don't know what you measured (Volts? Ohms? Current?).

Anyway, start with an external power supply of 5V and insert a current limiting resistor. At the junction of this resistor and the PIR, connect a potentiometer across the PIR. Send the wiper of the potentiometer to the sensor port and adjust the potentiometer such that it correctly responds to the PIR state. You'll need to select the current limiting resistor such that nothing burns up and the PIR semiconductor switch turns ON (there are minimum current considerations).

I'd start with a 220 Ohm current limit and a 2K potentiometer. Again, I'm flying blind.

Which is why I encourage, yea, exhort Ranger Home to read the instructions and follow them.

Bad assumption, I think

You're totally right.
The thread title says "stop voltage."
Then

So... that seems to be a resistance measurement. The only measurement that he didn't hint at is current.


Start with the freakin' instructions for each component you've got. Call the factory and ask questions. You still haven't given us the power (via brand and model number) to do your work for you. This leads us to ride off in every direction all at the same time, such as:

buzz's method here is very interesting but WAY too wonky and unnecessary. NOBODY makes PIRs that are any more difficult than ON and OFF states, unless they have timers built in. Timers are just retarded switches, so they add no need for further technology except waiting.

RTFM. Two times. Think. Sketch out a circuit. Check it against the manuals. Wire it up temporarily on your bench. Make it work. Come back and tell us what you worked out.

Its the Bosch Blue Line Gen2 PIR

[Link: us.boschsecurity.com]

I could ascertain nothing from the manual. I read it before posting here. If I just need to get a different sensor I will!

As a quick reality check have you forced a "contact closure" with a piece of wire to verify that your macro could work if external circuit conditions are favorable?