Lets continue this series on the Rule system. Today we are going to create some more advanced rules, and explain how it works under the hood.

Control multiple IO in sync

In this example we have two light in a room. And we want that when we press the switch both light goes ON simultaneously.

A basic approach of doing the rule would be:

That will work when both lights are synced, but the problem that need to be solved is that when lights are controlled directly (from calaos_home or calaos_mobile), and then pressing the switch, they could be out of sync. (first is ON and the second is OFF). The only way to put both lights in sync again is to do it manually. No so smart!

As you saw in the action popup, you can choose an action for the light from a predefined static list. Possible actions are for ex: toggle, true, false, … But there is a button right under the action, Dynamic value. This is where you can choose a value from an other IO. In concrete terms, after clicking the button you will be able to choose an IO, and when the action is executed, the value will be extracted from the selected IO.

Lets do that for the Light 2. So now in our example the first action is to toggle the state of the first light, and then assign that new state to the second light.
Now with such a rule, if the lights are not in sync, the second light will automatically be set at the same state. Of course this example can be repeated with other type of IO, like shutters. It’s extremely powerful when controlling multiple shutters with just one button.

Other approach

There is another way to sync both lights, by using a second rule. This time we will use a rule to toggle the state of the first light:

And a second rule with a condition that checks for the Light 1 state change. If the state changes, we update the state of the second light from the first light.

The fundamental difference between the two solutions exposed here is that the sync is done everytime the state of Light 1 changes, even when you control the light from the user interfaces. In the first solution that’s not the case, the second light is only synced when you press the switch.

The second approach is good when you need to link multiple outputs. You only need to do an action on the first IO, and the second will be updated automatically.

A question that comes very often in Calaos is “How does the rules system works in Calaos? How to do [name what you want here]?”. I’m going to start a series of posts to explain that with some real examples on how it actually works and how to do advanced tricks with Calaos. So, lets start with the basics.

Architecture

At the root of the entire system sits calaos_server. This is the main component of the system and its purpose is to talk to the underlying hardware (Wago PLC, 1-wire, Zibase, MySensors, …), execute some user defined rules, and export some API for the different user interfaces (calaos_home, calaos_mobile, webapp, …).

calaos_server acts as a daemon process and do what the user has configured in calaos_installer. Two types of configuration needs to be done, first declaring Items and devices in rooms (left part of calaos_installer), and finally creating rules using those items (right side of calaos_installer).

IO and rules

In calaos, all items declared are directly accessible from any user interface. For example, if you create a light, you can control that particular light on any interface. But when you create a switch, it will not do anything unless you create a rule that tells calaos what to do with your switch and eventually do an action like switch on or off your light. This is where rule comes in. A rule is basically an action that is triggered by an event. In our switch/light example, the event of pressing the switch will tell calaos to execute an action on the light.

Any rules are composed of a trigger event list and a actions. An event can also have some condition, but we will see that in a later post 😉

Basic example

Let’s start with a basic example of a switch that can switch on/off a light. First create our two devices, a switch and a light.

Next we are going to create a rule by clicking on the + button in the top right. Enter a rule name and type (for categorization) and click Ok. A new empty rule is created. You will see an empty condition list, and an empty action list. Let’s add the condition by dragging the switch in the condition list.

When adding a condition and clicking on it, you will see a popup appear. Here you can configure the condition. For now we can use the default values that means the event of: When the switch is pressed (true means the switch is active).

The first part of the rule is done, we need now to add an action to be executed after the switch is pressed. Lets drag the light to the action list.

The same kind of popup appears after adding the light to the list, it will let you configure what action to do for that particular light. Every items supports different kind of actions. The default action for a light is toggle which means invert the light state on every rule execution.

Now we have seen how to create a basic rule to handle a switch press that will toggle a light. Of course the same thing can be done for all the items and devices in calaos. All hardware devices (shutter, temperature, …) can have different actions or events, and calaos_installer tries to list them all in the action list.

In the next post we will see how to create more complicated rules. Calaos can also have some virtual items (timers, time ranges, variables, …), and they behave exactly the same regarding the event/action system.