Trend Log object (TrndLogS)

"Enable logging" indicates and controls whether (TRUE) or not (FALSE) logging of events and collected data is enabled. Logging occurs if and only if Enable is TRUE, "Local time" is on or after "Start time", and "Local time" is before "Stop time". If "Start time" contains any wildcards, then the conditions for logging to be enabled is ignored. If "Stop time" contains any wildcards, then the conditions for logging to be enabled is ignored. "Log buffer" records of type log-status are recorded without regard to the value of the "Enable logging" property.

"Logging Type" specifies whether the "Trend log" object collects records using polling, COV, or triggered acquisition.

"Logging interval" specifies the periodic interval in hundredths of seconds for which the referenced property is to be logged when "Logging Type" has the value POLLED. If the "Align intervals" property has either of the values COV or TRIGGERED, then the value of the "Logging interval" property is zero and ignored.

"Start time" specifies the date and time at or after which logging is enabled by this property. If any of the date and time fields contain wildcard values, then the conditions for logging to be enabled by "Start time" is ignored. If "Start time" specifies a date and time after "Stop time", then logging is disabled. A "Stop time" that is before the "Start time" is not allowed.

"Stop time" specifies the date and time at or after which logging is disabled by this property. If any of the date and time fields contain wildcard values, then the conditions for logging to be disabled by "Stop time" is ignored. If "Stop time" specifies a date and time earlier than "Start time", then logging is disabled. A "Start time" that is after the "Stop time" is not allowed.

"Stop when full" specifies whether (TRUE) or not (FALSE) logging ceases when the buffer is full. When logging ceases because the addition of one more record would cause the buffer to be full, Enable is set to FALSE and the event is recorded.

If "Stop when full" is writable, attempts to write the value TRUE to the property while "Record count" is equal to "Buffer size" result in the oldest log buffer record being discarded, and cause the "Enable logging" property to be set to FALSE and the event to be recorded.

"Buffer size" specifies the maximum number of records the log buffer can hold.

"Buffer size" can be written by any engineering and commissioning or operation and monitoring function. If "Buffer size" is changed to a new, smaller value, the oldest log records will be discarded as needed.
Note
In online mode, "Buffer size" can only be changed when enable logging is set to 'No'.
The value for "Buffer size" has to be equal or higher than the value for "Notification threshold".

"Align intervals" specifies whether (TRUE) or not (FALSE) clock-aligned periodic logging is enabled. If periodic logging is enabled and the value of "Logging interval" is a factor of (that is, it divides without remainder) a second, minute, hour or day, then the beginning of the period specified for logging is aligned to the second, minute, hour or day, respectively.

This property is required if the object supports clock-aligned logging. This property has no effect on the behavior of the Trend Log Multiple object if the "Logging Type" property has a value other than POLLED.

"Interval offset" specifies the offset in hundredths of seconds from the beginning of the period specified for logging until the actual acquisition of a log record begins. The offset used is the value of "Interval offset" modulo the value of "Logging interval". That is, if "Interval offset" has the value 31 and "Logging interval" is 30, the offset used is 1. "Interval offset" has no effect if "Align intervals" = FALSE. This property is required if the object supports clock-aligned logging.

"Log device object property" specifies the object property to be used as the BACnet "Trend log" object's data source. The data source object property is identified by a device object property reference, which includes the following elements:

• Device-ID: Specifies the device in which the data source object is located. For "Trend log" objects that support only local trending, the device ID element is omitted.
• Object-ID: Specifies the data source object.
• Property-ID: Specifies the data source property.

"Log buffer" is a list of BACnet logging records. Each log record conveys either a set of recorded data values or errors related to data collection, a status change in the "Trend log multiple", or an indication that the time and/or date was changed in the device hosting the "Trend log multiple" object.

"State flag" represents four boolean flags ("Out of service", "Overridden", "Fault", "In-Alarm") that indicate the general status of an object.

'Reliability' indicates whether the property value 'Present value' is reliable. If the 'Present value' is not reliable, the property 'Reliability' indicates the cause of the fault and the bit "Fault" of the state indication is set to 'True'. In a normal case, the property 'Reliability' is set to "No fault".

Property ID: 103

"Record count" represents the number of log records currently resident in the Log_Buffer. A write of the value zero to this property causes all log records in the Log_Buffer to be deleted and Records_Since_Notification to be reset to zero. Upon completion, this event is reported in the log as the initial entry.

BACnet property: [Record_Count]

"Total record count" indicates the total number of records collected by the BA-Trend-Log or BA-Trend-Log-Multiple object since its creation. When the value of Total-Record-Count reaches its maximum possible value of 232 – 1, the next value it takes is one. Once this value has wrapped around to one, its semantic value (the total number of records collected) has been lost but its use in generating notifications remains.

"Notification threshold" specifies the value of "Records collected since notification" at which notification occurs.

"Resubscription interval for COV" specifies the number of seconds between COV resubscriptions if the Trend Log is acquiring data from a remote device by COV subscription., provided that COV subscription is in effect.

• This optional property, of type Unsigned, specifies the number of seconds between COV resubscriptions, provided that COV subscription is in effect.
• SubscribeCOV requests specify twice this lifetime for the subscription and specify the issuance of confirmed notifications.
• If COV subscriptions are in effect, the first COV subscription is issued when the Trend Log object begins operation or when Enable becomes TRUE.
• If present, the value of this property is non-zero. If this property is not present, then COV subscription is not attempted.

"Records collected since notification" represents the number of records collected since the previous notification, or since the beginning of logging if no previous notification has occurred.

"Last notified record number" indicates the Sequence Number of the Trend-Record that caused the value of the Records-Since-Notification property to become equal to or greater than the value of the Notification-Threshold property. If no notifications have occurred since logging began, the value of Last-Notify-Record is zero.

"Notification class" holds a reference to a "Notification class object", and indicates which "Notification class object" to use when generating notifications for this object.

'Event enable' enables or disables specific event notification functionality (i.e. during engineering/configuration).

To-Offnormal

Allows TO-OFFNORMAL event notification functionality to be enabled and disabled.

To-Fault

Allows TO-FAULT event notification functionality to be enabled and disabled.

To-Normal

Allows TO-NORMAL event notification functionality to be enabled and disabled.

"Acknowledged transitions" conveys three flags that separately indicate the receipt of acknowledgments for TO-OFFNORMAL, TO-FAULT and TO-NORMAL events. These flags is cleared upon the occurrence of the corresponding event and set under any of these conditions:

• Upon receipt of the corresponding acknowledgment;
• Upon the occurrence of the event if the corresponding flag is not set in the "Event enable" property (meaning event notifications will not be generated for this condition and thus no acknowledgment is expected);
• Upon the occurrence of the event if the corresponding flag is set in the "Event enable" property and the corresponding flag in the "Acknowledgement required" property of the "Notification class" object implicitly referenced by the "Notification class" property of this object is not set (meaning no acknowledgment is expected).

"Notification type" conveys whether the notifications generated by the object should be of type "Event" or "Alarm".

"Time stamp of event" conveys the times of the last event notifications for TO-OFFNORMAL, TO-FAULT, and TO-NORMAL events, respectively.

"Enable event detection" allows to enable or disable event notifications of the corresponding object at engineering time. When "Enable event detection" is false, the internal algorithm of the object does not perform. Therefore, event notifications are not issued, and the dynamic properties of the object do not update.

"Event state" provides a way to determine if this object has an active event state associated with it. The "Event state" property indicates the event state of the object. Changes in the "Event state" property to the value FAULT are considered to be fault events. If the object does not support intrinsic reporting, then the value of this property is NORMAL.

Property-ID: 36

"Object access level" defines the instance-specific object access level. "Object access level" is used for generic filtering and processing an object by a client application.

• "Object access level" is a configuration property which can only be set up offline (ABT, application configuration).
• "Object access level" is evaluated by client applications such as Technical Operator, DB-Import, and APOGEE Point Team mapping.

Access level

Name

Description

7

Basic operation

Access to BACnet objects and properties for a room user e.g. data points visible on a room unit.

6

Standard operation

Access to BACnet objects and properties for standard operation and monitoring (daily business), .e.g. room and plant information on a management station.

5

Extended operation

Access to BACnet objects and properties for extended operation and monitoring such as network and device objects. All I/Os are visible

4

Administrator

Not used by HQ solutions yet.

3

Basic service

Access to BACnet objects and properties used for commissioning, e.g. configuration value extensions, I/O extensions, etc.

2

Extended service

Not used by HQ solutions yet.

1

Internal

Access to all BACnet objects and properties for very specialized actions e.g. during development.

"Object usage" indicates whether the object is used or unused. The "Object usage" property can hide or display respective objects and their functionality in a client. For example, room functionality can be marked for flexible room arrangements as used/unused. An object that is marked as unused behaves as if the object does not exist.

Property ID: 4930

"Description" is a string of printable characters whose content is not restricted.

"Object identifier" is a numeric code that is used to identify the object. It must be unique internetwork-wide.

"Object name" represents a name for the object that is unique internetwork-wide. The minimum length of the string is one character. The set of characters used in the "Object name" are restricted to printable characters.

"Object type " indicates membership in a particular object type class. E.g. "Analog input", "Binary output", "Event enrollment", "Trend log", etc.

"Building automation profile" is an enumeration that indicates a particular type of Siemens proprietary object. Siemens objects are based on standard BACnet objects. For example, Siemens Analog Input, Analog Output, Analog Calculated Value, and Analog Configuration Value are based on standard Analog Input, Analog Output, and Analog Value BACnet objects.

"Profile name" indicates the name of an object profile to which this object conforms. To ensure uniqueness, a profile name must begin with a vendor identifier code followed by a dash. All subsequent characters are administered by the organization registered with that vendor identifier code. The vendor identifier code that prefixes the profile name indicates the organization that publishes and maintains the profile document named by the remainder of the profile name.

A string of printable characters whose content is not restricted. (property is only used in ABT Pro)

Version of a copied object (copied from a library). (property is only used in ABT Pro)

Source of a copied object (copied from a library). (property is only used in ABT Pro)