Try this:

SELECT

HST_Currents.Timestamp_ID, Devices.name, Topics.short_name, Topics.name AS Expr1, Topics.short_units, Topics.description,

HST_Currents.Original_Value,

convert(varchar, DATEADD(s,(HST_Currents.Timestamp_id - 624511296000000000) / 10000000,'19800101'), 126) AS TimeStampDateTime

FROM Devices INNER JOIN

HST_Currents ON Devices.local_Device_ID = HST_Currents.Device_ID INNER JOIN

LoggedItems ON Devices.local_Device_ID = LoggedItems.Device_ID INNER JOIN

Topics ON HST_Currents.Topic_ID = Topics.topic_ID AND LoggedItems.Topic_ID = Topics.topic_ID