Square wave function/expression in CFX
 

I am working on a transient analysis and am wondering if there is any way to write an expression which will give a square wave function over the duration of the analysis.
The situation is I am analysing the heat entering a brake disc during repeated braking. I want to model a heat flux on a surface but switch it on and off as the brakes are applied.
For example, is it possible to model a 30 second transient analysis with brakes/heat applied for 5 seconds and released (disc able to cool) for 5 seconds then repeated two more times to see the disc temperature at the end of the analysis?
The square wave would then give a heat flux of xxx W/sqm for time 0 to 5 seconds and zero W/sqm from 5 to 10 seconds. It could be a binary function which is multiplied by the flux value.

I think u can use if or step function:
if( cond_expr, true_expr, false_expr )
or
step ()

either vhat parviz said or tabular data:
You can inport tabular data via user function