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Version: 24.2 (stable)

Trigger Messages Using Bits of a Variable

Messages are triggered by a state change in the PLC. If HELIO detects such a change, it'll add the corresponding message to the list of Active Messages. Once the condition changes again, the message will enter the Message Archive.

Here's where it gets really handy — HELIO takes care of all the low-level tasks like setting up databases in the background, so all you need to worry about is defining the messages and the trigger rules that tell HELIO when to actually trigger them.

In this first step, we'll look at the simplest way to trigger a message: by toggling the bits of a Data Variable.

1. Create a PLC Connection​

Our first job is to create a PLC Connection and bring in some variables.

PLC Mode is Required!

It is not possible to trigger messages using Placeholders for Offline Editing.

  1. Download & Start the Playground PLC

Setting up a PLC that we can connect to sounds pretty complex, right?

The HELIO Playground PLC Got Your Back

It's a software-based demo PLC that you can download for free and run on your development computer right away. A handy tool when you want to learn how to connect HELIO to an industrial machine that communicates using OPC-UA.

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→ Download the latest version and start it.

  1. Add the Connection

Good job on getting the PLC set up and running. Let's keep going:

  1. Explore the Structure

Once you've got the connection all set up, feel free to take a look and explore the data tree of the Playground PLC.

2. Import Trigger Variables​

Next, we need to create a variable that we can use to trigger messages based on certain bits. Fortunately, there's already one we can use. Let's add it to our project.

  1. Locate the BitSet/AsInteger Variable

Locate the variable in the Data Source Explorer. You should spot it under:
Objects > Examples > Concrete > Messaging > ProcessVariable.

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  1. Import the Variables

Let's import the variable into your HMI Data so that we can use it in our project. Since we are also going to use the two additional helper variables called SetBit0 and SetBit1, simply import the whole ProcessVariable folder.

Why Do We Need those Helper Variables?

The two helper variables are needed so that we can set the bits of our actual Process Variable BitSet/AsInteger. In a real project this is of course done by the PLC when certain conditions are met.

  1. Loosen Restrictions

To be able to write those variables, make sure to loosen the restrictions of the variables, so that we can read and write them.

Your HMI Data Explorer should look something like this:

3. Define Message Types​

Now that we've got the source, we need to figure out what the actual message should be. Let's get started on creating some Message Types.

  1. Add an Information Message
  • Switch to the Message Types View view
  • Choose the Add Type action and enter the details for our first message
  • The first message we are going to trigger is an Information message, so let's choose INFO-1 as the code and choose the appropriate level.
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  1. Add a Warning Message

We'll run this process again since we also want to trigger a second message. This time it'll be a Warning. Why not give it a try?

What do you think? Did it work? Your message configuration should now look something like this:

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4. Setup the Triggers​

Now that we've got a possible source, we need to define an actual Message Type that will get triggered and displayed.

  1. Add Your First Trigger

Switch to the Message Triggers View view, click the Add Type action and choose Process Variable as a trigger type.

  1. Configure the Trigger

Our first trigger is going to show our INFO-1 message whenever the bit with the 0 index of our variable is set.

  • Make sure to choose the right Source variable.
  • Enter the Code that goes with the message we just talked about.
  • As the Condition Bit Index you'll want to choose the 0 here because the condition should be watching the first bit of this variable.
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  1. Add Your Second Trigger

Our next trigger should display show our WARN-1 message whenever the bit with the 1 index of our variable is set. Give it a try and configure it.

Let's take a look at your result. Your trigger configuration should now look something like this:

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5. Create a Simulation Page to Trigger Messages​

The excitement is building because we're all set to start sending messages to our HMI. All we need to do is create a small page to simulate the whole thing. Thanks to HELIO, it's pretty simple. So let's get started!

  1. Add a Page

First things first, we need to create a page. To keep it simple, we're just going to create a basic Parameter Page:

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  1. Add two Magic Inputs and connect them

Next we're gonna need two Magic Input elements so we can toggle our Boolean (Data Variable Type) simulation variables we imported into our HMI in a previous step.

Once one of those variables is enabled, the PLC will set a bit in our Bitset/AsInteger variable, which will then trigger our message.

  • Select the Parameters slot and add two Magic Input elements
  • Connect the Value property of the first one with the /BitSet/SetBit0 and the second one with the /ProcessVariable/BitSet/SetBit1 variable
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  1. Simulate the Messages

Let's Get Those Messages Fired Up!

  • To connect to the actual PLC data, just switch to PLC Mode.
  • Switch to Test Mode so you can toggle the inputs.
  • Activate each of the two bits by toggling the inputs and you'll see the messages pop up.

Your HMI should behave something like this…

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Mission accomplished!

You've created your first message types and triggered them using an actual PLC. Ready to learn more how to display all active and archived messages? Check out the next step of the guide…