oven program r1

can someone take a look at this program for me and offer some advice.

i am really struggling on this one and i need some guidance. the oven is controlled by a set point which is a user variable entered on the TDE so it wont be the same set point all the time but i need it to turn a timer when the temperature is reached for example:

temperature = 100c

set point = 150c

when temperature = 150c it will enable a output to say the oven is at temperature and a count down timer can now be activated by a input when time as elapsed a output will come on but after the time as elapsed the timer can be started again so long as the temperature is at set point (this case 150c) 

in summary the timer can ONLY be activated when the temperature as reached set point.

like i said i am really struggling to make this work so a little guidance would be a great help.

thanks