IRead contract

This method is used to read the values of one or more data objects in a list.

Heritage: The method corresponds to the ISO 9506 Manufacturing Messaging Specification (MMS) Read service.  

This method is used to read an event list or a subset of it using a filter.  

This method is used to read the historical values at specific times for one or more data objects within a specific data journal list. If no entry exists at the specified time in the data journal for an object, the server creates an interpolated value for that time and includes it in the response as though it actually existed in the journal.

Heritage: The set of historical values is referred to collectively as a "Journal", as described by the ISO 9506 Manufacturing Message Specification (MMS). This method is derived from the ReadJournal service defined by that specification.

However, this method only accesses historical data rather than also accessing historical events as does the MMS ReadJournal service. This is because the return value of this method is strongly typed to historical data and not to historical alarms and events.  

This method is used to read changed historical values that for one or more data objects within a specific data journal list. Changed historical values are those that were entered into the journal and then changed (corrected) by an operator or other user.

Heritage: The set of historical values is referred to collectively as a "Journal", as described by the ISO 9506 Manufacturing Message Specification (MMS). This method is derived from the ReadJournal service defined by that specification.

However, this method only accesses historical data rather than also accessing historical events as does the MMS ReadJournal service. This is because the return value of this method is strongly typed to historical data and not to historical alarms and events.  

This method is used to read the historical values that fall between a start and end time for one or more data objects within a specific data journal list.

Heritage: The set of historical values is referred to collectively as a "Journal", as described by the ISO 9506 Manufacturing Message Specification (MMS). This method is derived from the ReadJournal service defined by that specification.

However, this method only accesses historical data rather than also accessing historical events as does the MMS ReadJournal service. This is because the return value of this method is strongly typed to historical data and not to historical alarms and events.  

This method reads the properties associated with a historized data object.

This method is used to read calculated historical values (averages or interpolations, for example) for one or more data objects within a specific data journal list. The time range used to select the historical values is specified by the client. Additionally, the client specifies a calculation period that divides that time range into periods. The server calculates a return value for each of these periods.

This method is used to read a list of historical alarms or events. This method only accesses historical events rather than also accessing historical data as does the MMS ReadJournal service. This is because the return value is strongly typed to historical alarms and event messages and not to historical data.

To simplify implementation, clients must first define a historical alarm/event list that the server will prepare to access.

Heritage: The set of historical alarms and events is referred to collectively as a "Journal", as described by the ISO 9506 Manufacturing Message Specification (MMS). This method is derived from the ReadJournal service defined by that specification.

However, this method only accesses historical alarms and events rather than also accessing historical data as does the MMS ReadJournal service. This is because the return value of this method is strongly typed to historical alarms and events.