Variable Frequency drive

Hi GUys;
I want to develop the programe in rs logix 5000 version 13.0 to control the Induction Motor Speed.But at initial stage i us ethe emulator for practice. I know that some Function are used but i do not where i can from start?
If any guy have a idea about that please share with me.
I want that in 20 sec the motor reaches at it full speed.
I also know the ratio of voltage over frequency is also used. i mean if voltage are 400 and frequency is 50HZ then the ratio of per hz is 8 rpm. But i do not know how the time manipulate with the frequency to achive the motor rpm at rated speed?
If any guy have a logic or document plz send me a link i am very thankful to him;
Thanks
Jcp

Which vfd model are you using with conjunction with the motor? Using a PLC to directly control a motor is impractical. Typical applications is send a reference frequency with a VFD, then allow the VFD to control the ramp rate most vfd's can acheive what you desire however we would also need to know the the torque requirements of your application. Is a high level of starting torque vs RPM required? If so then go with flux control VFD if its not a huge concern but a consideration senserless vector may be suitable. Also a description of your application would also help in deciding your torque curvature. In regards to S curve or linear ramp up.