diff --git a/Libs/CMS_CORE_Library.dll b/Libs/CMS_CORE_Library.dll
index bacfa06a..c0b42385 100644
Binary files a/Libs/CMS_CORE_Library.dll and b/Libs/CMS_CORE_Library.dll differ
diff --git a/Step.Database/Controllers/SessionsController.cs b/Step.Database/Controllers/SessionsController.cs
index 098d32f6..1cee1f81 100644
--- a/Step.Database/Controllers/SessionsController.cs
+++ b/Step.Database/Controllers/SessionsController.cs
@@ -35,6 +35,8 @@ namespace Step.Database.Controllers
                 .Sessions
                 .Include("MachineUser")
                 .Select(x => x.MachineUser)
+                .GroupBy(x => x.MachineUserId)
+                .Select(x => x.FirstOrDefault())
                 .ToList();
         }
 
diff --git a/Step.Model/DTOModels/AlarmModels/DTOAlarmHistoricModel.cs b/Step.Model/DTOModels/AlarmModels/DTOAlarmHistoricModel.cs
index ffbb536a..fa5d77f4 100644
--- a/Step.Model/DTOModels/AlarmModels/DTOAlarmHistoricModel.cs
+++ b/Step.Model/DTOModels/AlarmModels/DTOAlarmHistoricModel.cs
@@ -62,7 +62,6 @@ namespace Step.Model.DTOModels.AlarmModels
         [Required]
         public int PageSize { get; set; }
 
-        [Required]
         public string Title { get; set; }
 
         [Required]
diff --git a/Step.NC/NcHandler.cs b/Step.NC/NcHandler.cs
index 32251874..604cdeab 100644
--- a/Step.NC/NcHandler.cs
+++ b/Step.NC/NcHandler.cs
@@ -1557,6 +1557,11 @@ namespace Step.NC
             return numericalControl.NC_SetScreenVisible((Nc.SCREEN_PAGE)screen);
         }
 
+        public CmsError WriteM155Data(int process, double responseValue)
+        {
+            return numericalControl.PLC_WOperatorInputResponse(process, responseValue);
+        }
+
         #endregion Write data
 
         #region Siemens Tools
diff --git a/Step/Controllers/SignalR/NcHub.cs b/Step/Controllers/SignalR/NcHub.cs
index 9b38245b..7a922d10 100644
--- a/Step/Controllers/SignalR/NcHub.cs
+++ b/Step/Controllers/SignalR/NcHub.cs
@@ -210,5 +210,17 @@ namespace Step.Controllers.SignalR
                     throw new HubException(libraryError.localizationKey);
             }
         }
+
+        [SignalRAuthorize(FunctionAccess = GENERAL, Action = ACTIONS.WRITE)]
+        public void WriteM155Response(int process, double responseVal)
+        {
+            using (NcHandler ncHandler = new NcHandler())
+            {
+                ncHandler.Connect();
+                CmsError cmsError = ncHandler.WriteM155Data(process, responseVal);
+                if (cmsError.IsError())
+                    throw new HubException(cmsError.localizationKey);
+            }
+        }
     }
 }
\ No newline at end of file