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In there he creates a program (or edits one) depending on his need (more information here ). 

In the Blocks menu the user can find all the blocks that he can use

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From there, the user just chooses the variables (which he can see how to add them, in here)

Example

The above screenshot represents a very basic setup on how to use and apply the and block.

We set up the value of deltaT as a subtraction of cTRT and cTST, then if the value of the subtraction is greater or equal to 10 we turn the Alarm On, if not the Alarm is set to Off

At the end there is an Alarm routine, you ca find more about it here