TagMin Dynamic Time

Looking at the expression, ('METAL_LVL'-TagMin('METAL_LVL','*-7h','*'))/'CYCLE_TIME' , is it possible to have a dynamic '*-7h'...i.e... " '*-" & Cycle_Time+1 & " ' " ?

I want to create the abillity to look back into the process exactly 1 hour more than the cycle time. How can I code the expression so Pi understands the variable?

Thanks!

richshell_2000