Data Handling settings

Staggered Group Activation

This option directs PI Interface for OPC DA to inactivate all groups on startup and to stagger the activation of the groups based upon the offsets specified for the group’s scan period. This feature does not affect the operation of all OPC servers. It is intended to help level the workload by spreading out updates for groups that have the same scan period. (/ga).

Inactivate Groups on Startup

Inactivate all groups on startup. After the groups are built, they are activated. This option helps reduce the load on the OPC server during startup. (/gi).

Update Snapshot

If the current snapshot is a system digital state (such as I/O timeout, Shutdown, and so forth) and the interface reads in a new value that is older than the snapshot, the interface sends the new value one second after the snapshot time stamp of the system digital state. This check is omitted if the current snapshot is a good value. This is useful for setpoints that rarely change. (/us).

Ignore First Value

If the OPC server sends data before it reads its data source, it is likely to transmit zeros or erroneous values. This parameter directs the interface to ignore the first value that it receives after startup for each tag. (/if=Y).

Ignore Subsecond Timestamps

If the millisecond portion of the time stamp is not required, it can be truncated, which can speed up processing on Data Archive (/it=Y).

No Timeout

Direct PI Interface for OPC DA never to write I/O timeout errors, even if it loses its connection with the OPC server. Set this when configuring failover. (/nt=Y).

Disable Callbacks

Reduce the load on the OPC server by disabling call backs for polled groups. By default, polled groups have call backs enabled, but these call backs are not used by the interface. This option has no effect on advise groups. (/dc).

Write Status to Tags on Shutdown

This parameter specifies the digital state to be written to all PI points when the interface is shut down (/opcstopstat=state).

Note: In a UniInt failover configuration, the digital state is not written to points when an interface instance is stopped, because the other interface instance takes over writing data to the point.

Alternate Digital State for Questionable/Bad Qualities

Assign alternate digital states for questionable and bad qualities. To use this option, create a contiguous set of digital states in the system digital state set that corresponds to the set of states listed in the OPC manual, then assign the first digital state of the set to the command line option. (/as=system digital state). To view system digital states using PI System Management Tools, go to Points > Digital States.

Format of Timestamp Strings

Sets the format for time stamp strings read from or written to the OPC server. (/tf=format). For more information, see Time stamp adjustments.

Number of Tags in Advise Group

Configure the maximum number of tags for each advise group created with scan class 1. The recommended maximum is 800 tags per group, which is the default. Adjust this number according to the OPC server requirements. (/am=#).

Time Offset

If the OPC server node is set to a time zone other than the local time zone, this option directs the interface to adjust all the time stamps by the specified amount. To specify the offset, use the format [-]HH:MM:SS. (/to=offset).

Event Update Rate

Specify the requested update rate for the event class group. All event-based tags belong to the same group and the default update rate for the group is one second. If the OPC server’s data cache for event-based tags does not need to be updated every second, you can reduce load on the OPC server by setting this parameter to a higher value (a lower rate). For v2.0 servers, all events are read from the device, so this value can be set quite high unless there is some other reason to update the cache. Use the format /ER=HH:MM:SS.

Trend Advise

For advise PI points, send the value from the preceding scan if the new value's timestamp is greater than the number of scan periods (configured by the /ta parameter). Enabling this setting causes advise tags to behave as if the step attribute is enabled.

The log file will print a message indicating that TA is enabled.

Note: Enabling Trend Advise will disable ExcMax processing for Advise points. See Appendix A. Set ExcMax on advise and event points for details on ExcMax and Advise/event points.