The Event Counter Device provides a way of monitoring events on a wire. Typically, it's used to measure performance, as it can both count events and compute their frequency, but it can also monitor a terminal somewhere in a system to see how much activity it generates.
The Event Counter Device has one input terminal, "in", and two output terminals, "count" and "frequency". The "in" terminal should be wired to the terminal(s) of interest in the system. The "count" terminal will initially have a value of zero, but each time an event shows up on the Event Counter's "in" terminal, it will increase its "count" by 1. It will also update its "frequency" terminal, as long as events happen more often than about once per second.