def toMPlug(plugName):
    nodeAndAttr = plugName.split('.', 1)
    obj = toMObject (nodeAndAttr[0])
    plug = None
    if obj :
        depNodeFn = MFnDependencyNode(obj)
        attr = depNodeFn.attribute(nodeAndAttr[1])
        plug = MPlug ( obj, attr )
        if plug.isNull() :
            plug = None
    return plug
Get the API MObject given the name of an existing plug (node.attribute)
dataset/ETHPy150Open CountZer0/PipelineConstructionSet/python/maya/site-packages/pymel-1.0.3/pymel/api/allapi.py/toMPlug