Some webCoRE Basics for writing pistons - Triggers / Conditions

I regularly see questions of folks having trouble getting a piston to work properly.

Many times it is incorrect ordering / use of trigger comparisons (displayed with lighting bolt in webCoRE UI)

This example follows 'best practices':

Few things to note from this piston:

  • In the first if statement (line 21), there is one trigger comparison (since it uses AND; more than one trigger events can never occur at same time), and a condition comparison. (You can have multiple triggers in an IF, if it is OR, or FOLLOWED BY comparison).

    • In the webCoRE iDE (dashboard, staging, or local) when you select an if statement and add condition, the comparisons are organized by triggers and conditions.
  • Looking at the overall piston, All of the trigger comparison statements (if in this case) are at level 1 (looking left to right). ie trigger comparisons are not nested below other statements (such as then or else statements).

    • This is 'best practice' as many trigger comparisons are looking for changes vs. previous states, so the statement that includes the trigger comparison should be executed on each run
  • If you are using trigger comparisons and condition comparisons in an If (as shown in line 21), put the trigger comparison is first in the if statement.

    • in the latest version of webCoRE you don't have to do this, but it likely will help keep things clearer for you (and allows webCoRE to optimize your piston execution more)
  • In this example there are two if statements, each with one with trigger comparison

    • the overall flow of the piston should be that both if statements are crossed over (conditions are executed or evaluated) on a run (this example shows this correctly)
      • if you put in an exit statement in the piston, this may cause statements below the exit to not be crossed over, that may affect the trigger comparison tracking adversely (for those statements that are below the exit).

      • do remember that if your hub is down for a while, and then comes back up, this piston trigger comparison tracking may need to be updated to deal with any changes that happened (but were missed) during the hub downtime


Installation and Tips for webCoRE on HE

Piston images shown from webCoRE forum


Is Webcore internet based? i.e. will it run without an internet connection?

It will run without internet if you setup a local web server for the IDE html/css files.

See note 1,2 of the webcore install thread (listed above post)

All pistons run local from your Hubitat hub. The only thing web base is the interface for writing and saving pistons. If you want the web interface to be local also there is a procedure for doing that as well.


Download the Hubitat app