def METHOD_NAME(self):
    num_fan = self.get_num_fan()
    ret = "FAN_INDEX\t\tRPM\n"
    for i in range(1, num_fan+1):
        attr1 = "fan" + str(i) + "_input"
        output = pddf_obj.get_attr_name_output("FAN-CTRL", attr1)
        if not output:
            return ""
        #mode = output['mode']
        val = output['status'].rstrip()
        if val.isalpha():
            frpm = 0
        else:
            frpm = int(val)
        ret += "FAN-%d\t\t\t%d\n" % (i, frpm)
    return ret