Connecting PIR to ADI Ocelot

dominicv

Good evening Folks,

I apologize for some of my questions as they will certainly reveal my lack of expertize and knowledge in this field.

So lets go, I am trying to connect a PIR to my ADI Ocelot, SECU 16, card.

The SECU 16 is a configurable 8 input, which can be either, 8 Supervised input ( On/Off ) , 4 to 20 mA input or Analog input and 8 output.

Normally I would connect any On/Off type device like a switch,1 wire to an input and the other wire to ground this thrue a 1k Ohm resistor.

How can I connect the PIR since it only has 1 output wire.

Thanks for your assistance.

Regards

Confused Dom:nerd:

Franklin

The PIR provides power when it 'sees' movement so your input will have 0 or ~5v depending on movement or not.

Mike Green

Without more information about the SECU 16 card, it's difficult to say what you need. The PIR sensor produces a logic output where a low logic level is close to 0V (ground), usually between 0.3V and 0V. A logic high level is close to the supply voltage (Vdd) of the device which can be anywhere from 3.3V to 5V. The logic high output would be between Vdd-0.3V and Vdd. Usually in this situation, you'd use an NPN switching transistor like a 2N2222A or 2N3904. You'd connect the base of the transistor through a 3.3K resistor to the PIR output, the emitter of the transistor to ground (both on the PIR and the SECU 16 card), and the collector of the transistor through a 330 Ohm resistor to the Supervised input.

dominicv

Thanks Mike,

I think I understand.

I guess all these types of sensors weither they be motion, temperature or light intensity only provide logic hi or lo, depending on their state, in order for them to act as a switching device a transistor is required.

You mention the 2N2222, is this type of transistor available in a chip type package where you may have several 2N2222 in one package.

Thanks guys,

Dom:nerd:

Mike Green

You can use any NPN switching transistor for this sort of task. I'm sure they come in little SMT packages as singles or arrays. Depending on how the SECU 16 is designed, you might be able to connect the PIR directly to it or you might be able to use a non-inverting open-drain (or open-collector) buffer array. First thing is to look at the SECU 16's specifications.

dominicv

Good afternoon Mike,

The following is a brief overview of the SECU 16, if you are interested in finding out more, this is their site address : www.appdig.com/

Introduction
The SECU-16™ module allows 8 inputs and 8 low-current relay outputs to be added to an ADICON™ control system. The inputs may be supervised (switch closure), analog, or 4-20mA.

Specifications
Power: Input Voltage 9 - 12V DC or AC
Input Current Max 200mA

Inputs: 8 2-wire inputs, Analog (0 – 5VDC) or Supervised

Outputs: 8 Relay outputs 24VDC, 0.5 Amp

Dimensions: 5.5”W x 3.25”L x 1.38”D

Operating
Temperature: 0ºC to 70ºC



Setup

Remove the SECU-16™ top cover.
Connect the power supply to the two screw terminals labeled POWER.
Connect the COM A and COM B terminals to the ADICON™ bus (see Figure 1).



Figure 1. Typical Wiring Diagram

Three types of inputs may be used on the SECU-16™, supervised, analog, and 4-20mA. A supervised input is a passive, non-current supplying input such as a relay or switch. An analog input provides a varying voltage such as a light sensor. Input types are controlled by the jumpers as shown Table 1.

Jumpers P2 – P9 control the type if inputs used. P2 controls input 1, P3 controls input2, etc.
Input Type
P2 – P9
Supervised
2-3
4-20mA
1-2
Analog
Off

Table 1. Jumper Settings


Jumper 1&2 Jumper 2 & 3 No Jumper

To use an input as a supervised input a 1K Ohm resistor (supplied) must be placed across the input as shown in Figure 2.



The reason I am looking for several NPN 2N2222 in a single package is because I have purchased several motion detectors and light sensors which will all require to be mounted.



Thanks Mike for your assistance.



Dom:nerd:

Mike Green

It looks like the switching transistor solution may not work. It looks like they're expecting an isolated contact closure and an ordinary switching transistor won't supply that. The safest way to do this would be with a reed relay with a 5V coil or with an optocoupler. Either would provide the isolation and the contact closure (reed relay) or equivalent (optocoupler). With the optocoupler, the connection may be polarity sensitive and it would only work connected one way. The PIR could provide enough current at 5V for the optocoupler to turn on, but may not be able to provide enough for the reed relay. I've seen some 5V coil reed relays that will operate at 12mA to 15mA coil current which the PIR should be able to supply.

Look in the DigiKey or Mouser on-line catalogs for reed relays and see what's available with a 5V coil.

dominicv

Good evening Mike,

Further to your recent response, I was able to locate a schematics from Scary Terry, showing an assembly where the Parallax PIR was used.

Is the following pretty much what you had in mind, the RLY-470 needs to be replaced since it is no longer available, I could use a reed relay instead, I found one with a 10 mA required current with built in diode.

Does all this make sense, I would'nt no better.

Dom

Mike Green

Yes, that's what I had in mind.

dominicv

Mike, I thank you very much for your assistance.

To you and your family.

Merry Xmass and Happy New-Year.

Dom from Canada eh!