Pulse Generator - Can I control it using an external signal?

Hi,

Sorry if this is obvious but I am new to using Simulink. I am trying to build a single phase half wave rectifier using thyristors and therefore need to control the firing time of the thyristors based upon the firing angle specified. Although I can make this work by setting the pulse generator to the same frequency as the AC voltage source and then manually calculating the phase delay for the given firing angle, I want to know whether it would be possible to calculate the phase delay externally and then input this signal into the pulse generator automatically so it doesn't have to be calculated manually every time the firing angle is changed. I have managed to design a calculation to work out the phase delay as follows;

1) Time period = 1/Frequency

2) Then divide the time period by 360 and multiply by the firing angle (degrees) to get the phase delay.

The thing I cannot seem to work out is how to get the output value of this calculation to drop into the phase delay field in the pulse generator block so it automatically changes as the firing angle changes. Is this possible?

Many Thanks in advance :)