how to control the rotation noise frequency by an attribute holder parameter?

Hi,
First, you can't access the noise frequency directly with a wire parameter because it is not exposed as you say.
I came across a similar problem when I wanted to control the visibility of my IK/FK bones on a custom Rig. I don't know if my solution is a good way to do it, but it does the job without executing the script each frame.

The trick is to use the "on changed event" of your Custom Attribute to directly increment your target.rotation.controller.frequency

Since you don't want to break your script everytime you change the target's name (because of a scene merge for example), you can store your objects in a float script, via Assign Node. This float script can be applied on the wrist (on a list controller for example) or a dummy parented to your wrist ( I call that dummy a scriptHolder). However, that dummy should never be modified.

To access the target without naming it directly, you have to find where the float script is located, relatively to the object you are currently selecting, wich should be your attribute holder object (if you are modifying the spinner, that means you are neccessarily selecting your wrist)

There is an example of a scene containing a parent named MyAttributeHolder with a child named MyTarget.

fn Master_Custom_Attribute master = (
	local side = sideInt 
	local NoiseScriptHolder
	local fs_ScriptHolder
	local attrHolderMod
	local Master_CA 
	local oc
	
	NoiseScriptHolder = point cross:true box:false name: (uniquename "Noise_ScriptHolder_") size:5
	NoiseScriptHolder.transform = master.transform
	in coordsys #local (move NoiseScriptHolder [0,-30,0])
	NoiseScriptHolder.parent = master
	
	fs_ScriptHolder = float_script()
	NoiseScriptHolder[3][1][1].controller = fs_ScriptHolder 
	fs_ScriptHolder.AddNode "NoiseObj" $MyTarget

	NoiseFrequency_CA = attributes NoiseControl
	(
		
		fn ScriptHolderStart = ( --there must be a cleaner way to access the ScriptHolder
			local mySelection = $selection
			local theObj = mySelection[1]
			local theChildren = theObj.children 
			local ScriptHolder = for i in theChildren where (matchpattern i.name pattern:"*Noise_ScriptHolder_*") == true  collect i					
			local theHolder = ScriptHolder[1]
			
			return theHolder
		)
		
		
		fn NoiseControl theHolder NoiseObj increment = (
			local i = increment
			local NoiseNode = theHolder[3][1][1].controller.GetObject NoiseObj
			
			NoiseNode.rotation.controller.frequency = increment
		)
		
		parameters main rollout:params (
			NoiseFrequency_param type:#float ui:NoiseFrequency_UI default:1
		)

		rollout params "Noise Control" (

			spinner NoiseFrequency_UI "Frequency" type: #float range:[0,100,1] fieldwidth: 30

			on NoiseFrequency_UI changed i do (
				local holder = ScriptHolderStart()
				NoiseControl holder "NoiseObj" i
			)
			
			
		)
	)
	
	attrHolderMod = EmptyModifier()
	addmodifier master attrHolderMod
	Master_CA = master.modifiers[1]
	Master_CA.name = "Custom Attributes"
	custAttributes.add Master_CA NoiseFrequency_CA
		
)

Master_Custom_Attribute $MyAttributeHolder
 

Hey, thanks for the approach!
So let me recap to see if I got it right:
You use an additional object, which has a float script controller assigned, which is abused to store and retrieve the noise controller targets. then the custom attributes on changed event is looking up the stored node and sets its frequency parameter.

is this animatable, btw? so is the noise frequency getting updated if the master CA is animated?

what I dont get is how the storing of the targets as node in the float script keeps the rig from breaking..

*thinking out loud now*:
if the target gets renamed or deleted, will it not still break?
or is it like the "node" is the object and it doesn't care about its name. and you are looking it up by .getnode "variableNameInFloatScriptController". so it returns the object regardless of its name.
right?

so lets transfer this back to my situation.
I have 5 fingers with each 3 bones.
I want to be able to control each of their noise rotation controllers from the wrists master Custom Attributes.
that means the script holder object needs to hold all finger objects and I will have to create for each CA parameter an on changed event handler.

hm.
now that pops another question, since I am lazy and want to be able to generally reuse my script.
can this attribute creation, etc. be automated also via script?
I think I want to populate the extra noise holder object and also the CAs based on the available/selected (finger) bones.
so it sets up automatically a noise rotation controller for each finger, adds a CA for noise strength and frequency for thumb, index, middle, ring and pinky and connects them via the float script noise holder extra object.

actually I managed to create something similar in the meantime:

I used an extra custom attribute on my wrist controller, which got an expression controller assigned.
this controller manages for me the frequency on each finger noise controller (which are 15 in total)
it reads the global noise frequency custom attribute and feeds it back to the fingers.frequency property.
in the creation script I iterate through the fingers and update the expression of this "temp attribute".
I am not sure if this is a good idea, since the temp expression controller now updates all 15 noise frequency values each frame. but hey, it works for animating the global frequency attribute.

I hope I find the time today to post working example code.
I really want to enhance it and get a better understanding.
I also really hope to find someone who can help me further understand scripting for CAT system.

Thanks awesome community!