Every machine needs to provide messages to ensure proper functioning and prevent damage or safety hazards. HELIO uses three types of messages to provide guardrails on how to best communicate with operators.

• An Error occurs while the machine is running and requires human interaction to be resolved. Therefore, these errors typically need to be acknowledged by the operator to ensure that someone has actually provided a fix.
• A Warning is a message used to prevent errors from occurring in the first place. It provides operators with hints that certain thresholds have been exceeded and that it's time to act now in order to keep the machine running.
• All other messages fall into the category of Information. These messages can provide hints, tips on how to continue, or simply inform the user that a particular order has been completed. There are no limits to your imagination.

Usually, the PLC provides these messages as it needs to be the sole source of truth for its state, especially when it comes to errors. In order for HELIO to display those messages, the PLC must provide a way to:

• Query for messages
• Acknowledging messages

Step 1: Implement the API in your PLC

Follow the specifications provided in the HELIO Messaging API v1 to create a PLC capable of providing messages to HELIO.

Additionally, you can start a new project using the preinstalled Playground HMI Template. Connect it to The HELIO Playground PLC to view a live example demonstrating how HMI and PLC interact to generate a Message List.

Step 2: Import MessageList and AcknowledgeMessage in your HMI

• If you haven't already done so, add a new connection to your PLC.
• Locate and drag both the MessageList and AcknowledgeMessage into your HMI Data Explorer.
• Convert the MessageList into List (Data Variable Type).