Software that can read all devices ouputs

I have a system like this in my off-grid cabin but like many other posters mentioned it's customized for my particular setup and hardware.  All the data is collected and uploaded to a central server where it can be viewed/graphed over time via a web application.  The system consists of the following:

1. Odroid U3 arm board (much more powerful than a Pi) as the central controller.
2. Motion software running on controller monitors 4 security cameras and uploads images to web when motion detected.
3. Controller reads all modbus values from Classic 150/WhizBangJr over ethernet to provide SOC, in/out amps, voltages, etc.
4. Controller attached to an arduino Due via usb serial which reads three temperature sensors (inside, outside, utility room) and controls eight relays to turn specific loads on and off (i.e. water pump, fridge, inverter).
5. Uploads to server with Sprint 3G modem and Cradlepoint router.
6. Local web application runs on controller and allows control of relays and cameras as well as displaying real-time data.
6. Remote web application runs on central server and allows viewing of camera images, real-time data, and historical data.

So basically I can remotely monitor everything I need, including images from security cameras.  Everything runs linux and all the code except the arduino code is in python.  The data is stored in MongoDB which handles time series data better than a relational database.

The entire remote system draws about 50W including the controller, four cameras, arduino, relays, and 3G modem.

The one thing it currently lacks is the ability to manipulate the relays remotely or take a snapshot from one of the cameras.  I'm currently working on v2 which will have that capability.  The main differences in V2 are:

1. Uses MQTT as a messaging protocol so will have two way communication between the controller at the cabin and central server.
2. Uses an Odroid XU4 (8 core, 2GB ram, usb 3, gigbit ethernet ) as the controller ($75).
3. Uses latching relays so relay coils consume no power.
4. Uses Arduino Mega with ethernet shield.  The arduino has a MQTT client so I don't have to write my own protocol to communicate over serial like the previous version, it will just send and receive MQTT messages like everything else.
5. Added some PIR sensors to the arduino that will be placed near the cameras.  Hopefully this will allow me to eliminate some false positives generated by using strictly image based motion detection.
6. Wrote a native Android application that will display data and control relays, cameras, etc.  This replaces the local web application.

So that's my current and in progress solution to data collection and system control.  The v1 system has been running for about two years and has performed flawlessly.  I'm usually only at the cabin on weekends so it's great to be able to monitor everything remotely.

Yes, the Odroid can read the state of a switch using one of the digital inputs on the connected arduino.  For example, in the v2 system, the PIR sensors are just switches that close when motion is detected.  The v2 system can query any of the digital or analog input pins via an MQTT command sent to the arduino or you could program the arduino to send an MQTT command when the switch state changes.  For example, when the PIR sensors detect motion the arduino sends an MQTT message that it was triggered and another message when motion is no longer detected.  As I mentioned, I'm going to hopefully use this to improve the motion detection of the security cameras and I have a siren and flashing light I may connect as well to ideally act as a deterrent to would be thieves.

If the switch is actually switching something and thus carrying a voltage on the switched circuit you'd want to either use resistors and create a voltage divider to bring the voltage down to the arduino's input voltage of 5V or use some type of transistor or optoisolater.

As for the internet and firewall, I basically wrote two different web applications, one for the local network and another for the internet.  Version 2 will have the android app for the local network and a web application for the internet.  In v2, the odroid will run a local MQTT server which is bridged with an MQTT server on the internet server so all messages are received in both places and can be sent from inside or outside the firewall.  It greatly simplifies the transfer of data and I won't have to write any code to pass data between the two locations.  

The current system would require updating the arduino code to add a message sending trigger but the idea with version 2 is to specify a range of inputs that will send an mqtt message when the state has changed so when adding something new I can just hook it up to one of the free digital inputs.  I wired up 8 digital and 6 analog inputs to be usable as general purpose inputs.  Currently the PIR sensors use 2 of the 8 digital inputs.

The arduino's ehternet shield also has a micro sd card reader so I have the code read a lot of the configuration information from the sd card on startup.  So if I need to change the ip address or add another PIR sensor I can just update an .ini file on the sd card and the arduino will recognize it as a special type of sensor and send the corresponding messages as appropriate.  For example, if I add a 3rd PIR sensor I just need to connect the sensor and add the corresponding pin number to the config file on the sd card.  No reprogramming required.

In v2 the arduino and the odroid aren't physically connected, other than being on the same network.  So when the arduino sends an MQTT message like a PIR sensor being triggered, code on the odroid receives the message and can then start capturing video or snapshots from the cameras, switch a relay to activate the siren, etc.  Eventually I hope to have it send a text message to my phone with a snapshot from the camera also so I can determine the source of the motion.

With the current system I can go to the web application and see snapshots taken every second from the cameras when they detect motion.  I have a lot of pictures of birds flying in front of the cameras and spiders building webs.  At night the IR leds in the cameras attract flying insects which then attracts the spiders.  That's why I'm adding the PIR sensors to hopefully reduce false positives.

Here's a blog post with some pictures of the current system:  http://blog.flgator.com/2014-12-17-controller.html

The v2 controller board is about 1/3 the size of the current version you see in the pictures.