Content Comparison

The Field

Display

Collector

The collector ID, which is used to identify the collector in a Historian system.

Status

The current status of the collection. "Running" indicates that the collector is operating. "Stopped" indicates that it is in pause mode and not collecting data. "Unknown" indicates that status information about the collector is unavailable at present, perhaps as a result of a lost connection between collector and server.

Computer

The name of the computer the collector is running on.

Report Rate

The current rate in a number of samples/minute at which the server is receiving data from the collector. It is a measure of the collection rate and also of data compression activity. A value equal to the data acquisition rate, when Collector Compression Percent is zero, indicates that every data value received from the data source is being reported to the server. This means that the collector is not performing any data compression. You can lower the report rate, and make the system more efficient, by increasing the data compression at the collector. To do this, widen the collection compression deadbands for selected tags.

The Field

Display

Overruns

The overruns in relation to the total events collected since startup. This value is calculated by using the following equation: OVERRUN_PCT = OVERRUNS / ( OVERRUNS + TOTAL_EVENTS_COLLECTED ). Overruns are a count of the total number of data events not collected on their scheduled polling cycle. In normal operation, this value should be zero.You may be able to reduce the number of overruns on the collector by increasing the tag collection intervals (per tag).

Compression %

Percentage of how effective compression is at present for the specific collector since collector startup. A value of zero indicates that compression is either turned off or not effective. To increase the value, enable compression on the collector's associated tags and increase the width of the compression deadband on selected tags. The collector keeps track of how many samples it collected from the data source (OPC Server for example) and keeps track of how many samples it reported to the Historian data archiver (after collector compression is complete). A low number or zero means most everything coming from the data source is being sent to the Historian data archiver. The reason for the low number or zero is that too many samples are exceeding compression or you are not using collector compression. A high number or 100 means you are collecting a lot of samples, but they are not exceeding collector compression and therefore are not being sent to the server.

Out of Order

How many samples within a series of timestamped data values normally transmitted in the sequence have been received out of sequence since collector startup? This field applies to all collectors. Even though events are still stored, a steadily increasing number of out of order events indicates a problem with data transmission that you should investigate. For instance, a steadily increasing number of out of order events when you are using the OPC Collector means that there is an out of order between OPC Server and the OPC Collector. This may also cause out of order between the OPC Collector and the data archiver but that is not what this statistic indicates.