You may be surprised not to see Dimmer function in the list of functions on the Wireless I/O unit GUI if you had some experience before with programming of wired C-Bus Key units. Don't worry, Wireless I/O unit still has this function, but it is called "Toggle Dim Dn Cycle". You will see the reason why it was renamed if you look in this list of Dimmer related functions available on Wireless I/O unit:
"Toggle Dim Up Cycle" - Short press toggles assigned group on/off. Long press ramps the level up or down at rate. If you don't touch the key for at least 15 seconds and then press and hold it, group level will be ramping UP. Function has no analog in Wired Key units.
"Toggle Dim Dn Cycle" - Short press toggles assigned group on/off. Long press ramps the level up or down at rate. If you don't touch the key for at least 15 seconds and then press and hold it, group level will be ramping DOWN. Function is an analog of Dimmer (Toggle) function in Wired Key units.
"Mem Toggle Dim Up Cycle" - Short press toggles assigned group between previously set level and off. Long press ramps the level up or down at rate. If you don't touch the key for at least 15 seconds and then press and hold it, group level will be ramping UP. Function has no analog in Wired Key units.
"Mem Toggle Dim Dn Cycle" - Short press toggles assigned group between previously set level and off. Long press ramps the level up or down at rate. If you don't touch the key for at least 15 seconds and then press and hold it, group level will be ramping DOWN. Function is an analog of Dimmer (Memory) function in Wired Key units.
"Dimmer Up" - Short press turns group on. Long press ramps the level UP at rate. Function has analog in Wired Key units.
"Dimmer Down" - Short press turns group off. Long press ramps the level DOWN at rate. Function has analog in Wired Key units.
"Toggle Dim Up" - Short press toggles group on/off. Long press ramps the level UP at rate. Function has no analog in Wired Key units.
"Toggle Dim Dn" - Short press toggles group on/off. Long press ramps the level DOWN at rate. Function has no analog in Wired Key units.
As you see there are more dimmer related functions in Wireless I/O unit and it simply would be confusing to call one of them Dimmer.