detect a switch transition

I am trying to detect a switch transition, if the operator changes the switch position; I need to pop up a box to say this is a slow link.

I created a function where this works when everything is local, but when I link the switch to the server which is a Modbus object on a very slow link, I cannot read back the instantaneous position of the switch.

Am I missing a simpler way?

Lookout 6.6