A16v3 low voltage inputs

[jaydubnz]

Hi guys,

I have PIR sensors all over the house connected to an old alarm system. The voltage on the NO contacts are between 1.5v to 3v, which I think is too low for the digital inputs 1 to 16 to register as ON.
I know I can connect to the 5 analog inputs, which does detect the low voltage, but I have ~15 sensors. Is there a way to make these low voltage PIR sensors detectable on digital inputs 1 to 16? Without using a ton of dry contact relays haha

Thank you in advance!

[admin]

use a 3v relay is easiest way.

[jaydubnz]

Thanks admin. So i need to get 15 relays? No easier way?

[twostar]

I have PIR sensors all over the house connected to an old alarm system. The voltage on the NO contacts are between 1.5v to 3v, which I think is too low for the digital inputs 1 to 16 to register as ON.

The inputs are dry-contact, there shouldn't be any voltage on them.  Do the sensors have EOL resistors which could be presenting a voltage on the input?

[jaydubnz]

I have PIR sensors all over the house connected to an old alarm system. The voltage on the NO contacts are between 1.5v to 3v, which I think is too low for the digital inputs 1 to 16 to register as ON.

The inputs are dry-contact, there shouldn't be any voltage on them.  Do the sensors have EOL resistors which could be presenting a voltage on the input?

Hey, yes they do!
I just read the PIR manual and it says it supports up to 24V DC for the input and output.
I'm quite a noob at all this stuff, I'm assuming the EOL resistors are lowering the output voltage down to 1.5v. 
Might replacing them with a lower ohm rating increase voltage to 12v? Is this a good idea, or would it cause a lot of power draw and heat / fry my alarm panel board? hehe

thank you!

[twostar]

You need to remove the EOL resistors entirely, a dry-contact input can only have two states, either open-circuit (open) or short-circuit (closed).  The EOL resistors are putting a voltage across the input that shouldn't be there.

[jaydubnz]

You need to remove the EOL resistors entirely, a dry-contact input can only have two states, either open-circuit (open) or short-circuit (closed).  The EOL resistors are putting a voltage across the input that shouldn't be there.

Thanks, I just tried taking off the EOL resistors. 
Now it goes from 0 to 8v. So close! 

But still not triggering the digital input on the Kincony board. :~)
I guess I have to buy some relay modules

Thanks again for your help!

[Michaelmur]

You need to remove the EOL resistors entirely, a dry-contact input can only have two states, either open-circuit (open) or short-circuit (closed).  The EOL resistors are putting a voltage across the input that shouldn't be there.

I think I'm having the same problem...Been working at this for days.. 
I bought the KC868-A16 because I have about 10 LD2410 sensors that I wanted to connect. The LD2410 has an OUT pin that outputs 3.x volts when someone is detected, and LOW when they are not.  The 1-8, 9-16 pins are all registering about 10v and don't react to the LD2410's 3.3v output. 

Do I need to attach 16 relays to close the input pins?

thanks

[twostar]

The LD2410 has a TTL output (or at least a 3.3V output) meant for interfacing to Arduinos, it's not meant to be fed into a dry-contact input which relies on pulling the input down to GND to light the optocoupler LEDs.  You could do something like creating a battery of MOSEFT switches to perform the conversion, but that'd require custom circuitry.  Another option which would require surgery on the KC868 is to bypass the optocouplers and feed the LD2410 output directly into the PCF8574 inputs, but then you're losing the protection on the inputs that the optocouplers give you.

You could try asking on somewhere like EEVBlog to see if anyone has any ideas.