Index: leahi_dialin/utils/nv_ops_utils.py
===================================================================
diff -u -r18c90a1b2b6c7339bdd192a2d2fac32f2b8a35df -r6d104d3185ac3ed7c18c97ecdc13fd59bf53a8d1
--- leahi_dialin/utils/nv_ops_utils.py	(.../nv_ops_utils.py)	(revision 18c90a1b2b6c7339bdd192a2d2fac32f2b8a35df)
+++ leahi_dialin/utils/nv_ops_utils.py	(.../nv_ops_utils.py)	(revision 6d104d3185ac3ed7c18c97ecdc13fd59bf53a8d1)
@@ -21,7 +21,8 @@
 from typing import List
 from collections import OrderedDict
 from .excel_ops import *
-from leahi_dialin.utils.base import AbstractObserver, DialinEnum
+from leahi_dialin.utils.abstract_classes import AbstractObserver
+from leahi_dialin.utils.enums import DialinEnum
 
 
 @unique
@@ -34,6 +35,7 @@
     NVDATAMGMT_USAGE_INFO_RECORD = 5
     NVDATAMGMT_SW_CONFIG_RECORD = 6
     NUM_OF_NVDATMGMT_RECORDS_JOBS = 7
+NVRecordsDG._str_list = {}
 
 class NVRecordsHD(DialinEnum):
     NVDATAMGMT_CALIBRATION_RECORD = 0
@@ -43,8 +45,8 @@
     NVDATAMGMT_USAGE_INFO_RECORD = 4
     NVDATAMGMT_SW_CONFIG_RECORD = 5
     NUM_OF_NVDATMGMT_RECORDS_JOBS = 6
+NVRecordsHD._str_list = {}
 
-
 class NVUtilsObserver(AbstractObserver):
     """
     Observation class