Scripts in smart rules and notifications

Overview#

Smart rules give their script the values of the devices picked as variables, under their abbreviations, and use the result in different ways:

SLEEP is rejected in all smart rule and notification scripts with SLEEP function not allowed in this context. The only exception is the Formula limiting condition, which accepts it; do not use it there either, because it holds up the evaluation of smart rules. ADDERROR, ADDWARNING and ADDINFO fail here with ADDERROR function not supported here.; they work only in device scripts.

Equation smart rule#

The Equation smart rule evaluates its script whenever one of its variables changes, after it is saved and after the Core starts. The result is read as a boolean, where a non-zero number is TRUE. Actions run only when the result changes, so one-time actions and notifications fire once per change.

• A Null result or a script error releases the devices the rule controls; the next TRUE or FALSE result applies its actions again. A text result is reported as a formula error.
• LastState is the previous result of the script, FALSE on the first run and after a Null result or an error.
• TriggerName is the abbreviation of the variable whose change caused the evaluation, empty after a save or a restart. Available from Core 2026.1, build 35936.

A light that switches on below 20 lx and stays on until 60 lx:

(!LastState AND Li < 20) OR (LastState AND Li < 60);
# Result: TRUE below 20, then TRUE until Li reaches 60

The same configuration step by step is in Configuration using LastState.

Formula smart rule#

The Formula smart rule writes the result of its script to every output variable. In Evaluation mode you choose when it runs: When any of input variables changed, or On custom event, where only the triggers of the rule start it and the variables are just read.

• The result may be of any type the output accepts. A Null result is written as well.
• LastState is the previous result. It is Null on the first run and after a script error, so guard it before using it in arithmetic.
• TriggerName is the abbreviation of the input variable that changed, or the name of the trigger that fired.
• A device that is missing reads as Null; check such inputs with ISNULL.

Counting door openings with the custom event mode (the trigger is the door contact opening):

IF(ISNULL(LastState), 0, LastState) + 1;
# Result: 1 on the first run, then 2, 3 and so on

A thermostat with HYSTERESIS uses the same guard:

HYSTERESIS(Se, 23, 21, 0, 1, IF(ISNULL(LastState), 0, LastState));

Script smart rule#

The Script smart rule has two lists of variables, Read-only variables and Read/write variables. Assigning a read-write variable creates a device action; several assignments to one device are merged into one action. The editor shows Script has to contain at least one assignment. until the script contains :=.

IF Se > 25
    Mu := 1;
ELSE
    Mu := 0;
END

• It runs when Any of the read-only variables changes, or On custom event.
• Only the variables assigned in this run are written. When the rule holds its actions, a run that assigns only some read-write variables releases the others, and a run that assigns none releases all of them. A lower-priority rule or the default value then takes over. Assign every output in every branch, as in the example above.
• A script error releases every held output. A value of the wrong type for a device discards the whole run, including the assignments before it.
• TriggerName is the abbreviation of the read-only variable that changed. It stays empty when no read-only variable is marked as a trigger. With custom events it is the name of the trigger that fired. The script can also assign it.
• There is no LastState.

Formula limiting condition#

The Formula type of a limiting condition evaluates a script over its own variables. TRUE lets the smart rule run; FALSE, Null or a script error blocks it.

Te < 22 AND Hu < 70;

Notification scripts#

The title and the message of a notification are scripts that must return text. They can read the devices picked for the notification and the notification constants listed in Context constants.

"Temperature in " + LocationName + " is " + TOSTRING(Te, "F1") + " °C";