This block detects the time instants at which the input signal crosses the level specified by the user, and produces an output with a constant value vOut.
It may seem a bit strange that the generated output values are always the same (constant). Considering however that the CrossDetect block is aimed at detecting the time instants when a signal crosses the given level, the actual value of the output does not matter, but only the fact that there are output events in the appropriate moments. The interesting output variable is therefore the auxiliary variable showEvents. It is a very simple Integer variable that is incremented by 1 each time an output event is generated, the scope of which is just to have a variable with a value that changes at event instants.
The picture below illustrates the behaviour of a CrossDetect block that discovers the crossing instants of a given level (green) and the actual input signal, the sine signal (blue). The variable CrossDetect.uVal[1] is given in pink, but as can be easily seen it is of little use, since after the first crossing instant it just jumps from its initial value (zero) to vOut and stays there. For this reason, also the variable showEvents, the time component of the output vector, is depicted. Given the fact that this variable indicates the time instants when the sine signal crosses the level, it can be said to be the actual output of the CrossDetect block while the usual output variable (CrossDetect.uVal[1]) is rather a dummy variable, this time.
.ModelicaDEVS.FunctionBlocks.CrossDetect