The If block contains a condition port. This allows it to act on a link. 

The main particularity of this block is that it has one inflow gate and 3 outflow gates

The inflow gate can be linked to the Start block, or to another block that has an outflow gate providing input to the If block.

The outflow gates will be linked to each possible output

then - will follow a course if the condition is met

else-  will follow a course if the condition is not met 

next - (optional)will go to next action regardless of the then/else outcome

 

If block Example:

The program can be interpreted as thus: If the temp is higher than 95 degrees, then turn the chiller on else  do not turn it on. Next, start someMacro.