In some systems, a MDIS Server might be on an isolated network, one in which there is no NTP or other source of time synchronization signals. In these systems, the MDIS Server would need to be able to obtain a minimum time synchronization signal from the Client. This ObjectType and associated method is designed to allow this minimum time synchronization. It should only be used if a better time synchronization system, such as NTP, is not available. The accuracy of this type of time synchronization could be in the range of seconds.

If this Object is supported, a single instance of this Object shall exist on a Server. The Object shall have a name TimeSynchronization and the instance shall exist as part of the MDISInformationObject.

The following section details the MDISTimeSyncObjectType. This optional type allows a Client to provide time synchronization information to a Server. The Client can call the SetTime Method periodically to ensure the Server time does not drift. This Method does not return until the time on the Server has been updated or an error is returned.

Figure 18 - MDISTimeSyncObjectType

Table 32 defines the structure of an MDISTimeSyncObjectType.

The current time on the Server is available as part of the ServerStatus provided by all OPC UA Servers.

Table 32 - MDISTimeSyncObjectType

Attribute	Value
BrowseName	MDISTimeSyncObjectType
IsAbstract	False
References	Node Class	BrowseName	DataType	TypeDefinition	ModellingRule	RW
Subtype of the BaseObjectType
HasComponent	Method	SetTime	SetTime Method is defined in 5.9.4		Mandatory

SetTime – This method allows a Client to set time on the Server.

SetTime Method (defined in Table 33) is used to set the time on the Server. If an error occurs this Method shall return an error code indicating the failure to set the time (see Table 35).

Method Declaration

SetTime (

[in] TargetTime UtcTime

);

Table 33 - SetTime Method parameters

Argument	Description
TargetTime	The UTC Time that the Server shall use to update its internal clock.

Method result codes are defined as part of the Call Service (see OPC UA Services Part 4 – Services specification). They are described in Table 94 for ease of reference.

Comments

The SetTime Method will change the time on the Server. Table 10 specifies the AddressSpace representation for the SetTime Method.

Table 34 - SetTime Method AddressSpace Definition

Attribute	Value
BrowseName	SetTime
References		Node Class	BrowseName	DataType	TypeDefinition	Modelling Rule
HasProperty		Variable	InputArguments	Argument[]	PropertyType	Mandatory

Table 35 – SetTime Result Codes

Symbolic Id	Description
Bad_InvalidTimestamp	The timestamp is outside the range allowed by the Server or an error occurred setting the Server time.
	.