Get all elements listed in a Schedule

try this

import clr
import sys

import RevitServices
from RevitServices.Persistence import DocumentManager 

clr.AddReference("RevitAPI")

import Autodesk 
from Autodesk.Revit.DB import *

doc = DocumentManager.Instance.CurrentDBDocument

schedview=UnwrapElement(IN[0])
coll=FilteredElementCollector(doc,schedview.Id).WhereElementIsNotElementType().ToElements()
OUT = coll

cordially
christian.stan