GetSliderValue

using UnityEngine;
using System.Collections;
using UnityEngine.UI;

public class GetSliderValue : MonoBehaviour {

	public YourScript yourScript;

	void Awake () 
	{
		if (yourScript==null) Debug.LogError("No yourScript assigned at "+transform.name);
		var slider = GetComponent<Slider>(); 
		slider.value = yourScript.sliderValue; // init with value from script
		slider.onValueChanged.AddListener((value) => { yourScript.sliderValue = value; }); // send value
	}
}