# Diagnostics

Diagnostic variables are available for store operation diagnostics. They are represented as OPC UA items and described below. 

Only diagnostic variables that are common for all types of stores are described here:

![](https://4282443477-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F3cwznMbQcEQxtnjiRDYX%2Fuploads%2FOoMvLe8P8ZLXUL4UzYqX%2FDiagnostics%20\(360034374872\)_image-0.png?alt=media\&token=aa18d8a0-2fb6-4270-9d1f-45d09c5e65a2)

* **GoodResponses:** contains the total number of successful responses from the database when preparing or writing data.
* **LastResponseUtcTime:** contains the time of the last successful response from the database in the UTC format.
* **BadResponses:** contains the total number of unsuccessful or unreceived (during loss of connection) responses from the database.
* **LastErrorUtcTime:** contains the time of the last unsuccessful or unreceived response from the database in the UTC format.
* **HasError:** indicates whether the last request sent to the database was successful or not.
* **DemoIsExpired:** contains that demonstration period for the store is expired.
* **MaxWriteDuration:** contains the longest time interval between sending a write request and receiving a response.
* **MaxPrepareDuration:** contains the longest time interval between sending a database preparation request and receiving a response.