Real-Time Expressions: Search for and Display an Error


Search for an error or specific condition and display a message in a summary tile. If no error or specific condition is found, display a default message in the tile. This operation utilizes the map operator, :, and the union operator, |


=(([data stream] <operator> <value>) : "error message" ) | "default message"


The example above contains a data stream called "velocity". We want to detect if any value inside this data stream exceeds 60. If it does, a tile in the bottom right will display the message "Exceeded 60 IPS!". If no value inside the data stream exceeds 60, the tile will display the message "No Errors Detected!".

Add a new tile, select the tile type to be "Summary", and use the following expression shown above:
=(([velocity] > 60) : "Exceeded 60 IPS!") | "No Errors Detected!"

The union operator, |, gives the left operand a higher priority. If any value in velocity exceeds 60, the map operator, :,  will replace that value with "Exceeded 60 IPS!". If no value exceeds 60, then the left operand is empty. The union operator then assigns the resulting value displayed with "No Errors Detected!"

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