Let me set some things straight to sort out the confusion.
First, it is acknowledged that dimmer packs, switching packs and power packs(here-after all inclusively called dimmer packs) are all DMX devices. That is undeniable.
Second, on their own, the dimmer packs are not a fixture. By fixture, I am refering to a piece of electronics that is designed to produce light for the purpose of illumination, not "on unit displays". Also, some motors have DMX functionality but that's a different yet related issue.
MyDMX doesn't have profiles for dimmer packs for a very simple reason. It's not necessary. Why? Because the dimmer pack itself is an intermediary device to get something else to work.
Case and point. Let's say I have a dimmer pack. This dimmer pack, just for the sake of argument is an ADJ DP-DMX20L, a fairly common dimmer pack capable of using 4 DMX channels. So, a profile should be made for the dimmer? No, it shouldn't. And here is why:
Let's assume I have 4 Par64 lights on the dimmer pack, 1 per channel. I can, via a DMX controller, such as MyDMX, control the intensity of those 4 Par64 lights via sending control instructions to the dimmer pack.
Giving a profile to the dimmer pack itself is useless. What is more critical is assinging a profile for the devices hanging off the dimmer pack, which in this care are Par64 lights. Simply select 4 Par64 profiles, each assigned to the appropriate channel and you are good to go.
But what if you're not using something like a Par Can? Then chances are you are using a "Hi-Tech FX" type fixture. In which case, MyDMX doesn't really have a profile for those either, so the advise for that is to select a generic so you can tell in the 3D Visualizer that it is turned on, which is about the only amount of control you're gonna have anyways.
Honestly, MyDMX doesn't care what you have assinged to a channel. These profiles are for your benefit anyways. It's not like if you swap out the Par64s for Par38's and don't tell MyDMX that it's honestly going to make a difference to MyDXM, because MyDMX doesn't care, nor is it its job to care.
So, think one step outside the box. Dimmer packs control or operate fixtures, so therefore assign the profile to the channel(s) used by the dimmer pack appropriate for what is hanging off the dimmer pack, but not the dimmer pack itself. When you think this way, it makes perfect sense. Think about what you're doing, not necessarily how you get the work done(as in through/via a dimmer pack).
It is a slightly abstract concept, but simple to resolve.
I hope this clears up some confusion.
Now, get back to programming your shows. MyDMX rules!