ahmed yousri wrote:i want to know what is ramp function

This function is carries on the output in the stipulation time from the starting value to the end value.
For example:
The starting value is 100, the end value is 1000, outputs in 10 seconds finished, this time each second is the output (1000-100) /10=90, therefore, when uses the RAMP function, is the first second outputs 100, the 2nd second outputs 190, the third second outputs 280, ......Until outputs 1000, like this we seem look like each one stair's output, therefore is called the Ramp function.
Good Luck