So, if I'm right, you intend to use it to log effects inside the PLC when a certain trigger happens (like a something passes before a photocell).
That can indeed be a very handy tool. Thanks for sharing.
Although it's bad practice to use this in an operator screen (locking up the interface for an operator will cause frustration), it's not such a big issue if you do it for diagnostics, and only technical people are supposed to use it.