Skip to main content

Trigger Messages Using Bits of a Variable

In the previous step, we looked at using numeric variables and thresholds to trigger messages.

But often you just want to use a simple boolean logic to trigger messages. For example you might want to show a certain message when the PLC sets a certain switch and hide the messages as soon as the PLC resets the switch.Toggling messages like this is a piece of cake when using the bits of a variable.

So in the next step, we'll learn how to trigger messages by toggling bits on a Data Variable.

1. 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.

←→
  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. Set 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:

2. 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.
←→
  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:

←→

3. 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.
←→
  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:

←→

4. Create a 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:

←→
  1. Add two Magic Inputs and connect them

Next we're gonna need two Magic Input elements so we can toggle our Boolean 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
←→

5. Let's Simulate 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…

←→
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…