Enable from configure->automation->features the "X10 - Dimmer Bright 100% when switched on" program.
This will automatically set dimmers to 100% when switched on.
You can also configure the memory level feature for your dimmers so after switched on, these will be set to the last known level.
So in a script you can use the sequence:
---
Control.On (the dimmer will be brighten to 100%)
Control.Level 30 (that will dim light to 30%)
---
Control.Level accept absolute dimming values.
Cheers,
g