Trend extension attributes

Trend extensions contains attributes common to Metasys system objects.

The following table lists the attributes specific to the trend extension. Click the attribute name in the table for a description of the attribute.

Note: In the Notes column, letters indicate the following: C - Configurable, D - Default Attribute for Display, N - Value Not Required, R - Affected by Extension’s Reliability, W - Writable.

Table 1. Trend Extension Attributes
Attribute name	Notes	Initial value	Values/Options/Range	Description
Acked Transitions	C,W	False, False, False		Conveys three separate flags that each indicate if the most recent To Offnormal, To Fault, or To Normal event transitions have been acknowledged (if the transition requires acknowledgement).
Buffer Size	C	144	1–5,000	Specifies the maximum number of records the buffer may hold.
Buffer State		Operational	Operational, Buffer Full	Indicates whether the buffer is full or operational when the Stop When Full attribute is set to False.
Client COV Increment	C,W			Specifies the increment used to determine that a change of value occurred (when this trend object collects data by COV). If the referenced object and attribute support COV reporting, then this attribute may have a Null value. In this case, the value of the trended object for COV increment is used. This value only applies to trended values of the real value (floating point) type.
COV Resubsc Interval	C,W	3,600	Units = Seconds	Specifies the number of seconds between COV resubscriptions (when this trend object collects data by COV). This attribute is only used when the trended object is a BACnet Integration point on the IP network. The Subscribe COV requests specify twice during this interval for the actual subscription. The first subscription is issued when the trend object begins operation or when enabled.
Enable	C,W	False		Indicates and controls whether logging is enabled (True or False).
Event Enable	C,W	True, False		Determines whether notifications are enabled for To Fault and To Normal events. A To Normal transition occurs when the value of the Records Since Notify attribute is equal to or greater than the value of the Notify Threshold attribute. A To Fault transition occurs when an attempted COV subscription fails. The To Normal transition must be enabled and set by default. The Read and Write methods ensure this value cannot be set to False.
Event State			Normal, Fault	Determines whether an active event state is associated with this extension. The value is set to Normal when there is no intrinsic alarming defined for this object. If intrinsic alarming is enabled (Enable Intrinsic Alarms = True), then this value is either Normal or Fault (problem occurred with the object subscribing for Change of Value [COV]s). This attribute appears on the view when the site is defined as a BACnet site.
Event Time Stamps				Conveys the times of the last event notifications for To Offnormal, To Fault, and To Normal events. Time stamps of type Time or Date have FF if no event notification of that type has generated since the object was created.
Input Reference	C			Defines the attribute of the object being sampled. This attribute is used for consistent references to an object or attribute. The Input Reference and the name of the object and attribute you want to trend must match exactly.
Intrinsic Alarming Defined	C,W	False		Enables (True) or disables (False) BACnet intrinsic alarming for this object. When disabled, writing to any of the intrinsic alarming attributes returns a Write_Access_Denied error. When disabled, reading the intrinsic alarming attributes returns the default value of each attribute.
Last Notify Record		0		Indicates the sequence number associated with the most recently collected record whose collection triggered a notification (that is, it caused the value of the Records Since Notify attribute to be equal to or greater than the value of the Notify Threshold attribute). If no notification has occurred since logging began, the value of this attribute is 0.
Logging Type		Polled	Polled, COV, Trigger	Specifies the method for which the referenced property is logged (Polled, Change of Value [COV], or Trigger).
Log Interval	C,W	60,000	Units = 100ths of a second	Specifies the periodic time in seconds for which the referenced property is logged.
Notification Class	C,W	1		Specifies the notification class used for handling and generating event notifications for this object. Notification occurs based on the value of the Records Since Notification attribute. The Notification Class attribute implicitly refers to a Notification Class object that has a Notification Class property with the same value. If the class number references a non-existent Notification object, no Notification occurs. When the Notification Class attribute is written online, the Notification Object Reference is updated to the Object Reference of the Notification Class object with that instance number, if found. If the Notification Class object for a Johnson Controls proprietary object is not found, the reference is left blank. If both the Notification Object Reference and the Notification Class attributes are written simultaneously online (or both are configured and downloaded), the Notification Class attribute value is set to the value that was written to the Notification Object Reference, and the Notification Class value in the write message is ignored.
Notification Object Reference	C,W		Limited to Notification Class on the same device.	Specifies the Notification Class object used to route alarms for the object being configured (through tree selection). When the Notification Object Reference is written, the value of the Notification Class attribute is updated to reflect the referenced object’s instance number. The value of the Notification Object Reference attribute is restricted to Notification Class objects on the same device as the alarming object. Validation only occurs during a write, not during a create (the download does not fail).
Notify Threshold	C,W	130 (90% of Buffer Size)		Indicates when notification occurs based on the value of the Records Since Notification attribute.
Notify Type	C,W	Events		Conveys if the notifications generated by the object are Events or Alarms. This attribute is required if the object supports intrinsic reporting.
Record Count	C,D,W	0	0–5,000	Represents the number of samples recorded since the creation of the trend extension or the last time the buffer was cleared, when the Stop When Full attribute is set to True. Represents the position of the next sample recorded, when the Stop When Full attribute is set to False. A value of zero for this attribute deletes all records in the log buffer and resets Samples Not Sent to ADS and Total Record Count to zero. If the buffer overflows, the Record Count resets to zero.
Records Since Notify		0		Indicates the number of records collected since the last notification occurred or since logging began if no notification occurred.
Reliability		Reliable	Uses Reliability (Set 503).	Represents the reliability of the Present Value. If the Input Reference becomes unreliable, the trend extension monitoring the input becomes unreliable.
Repository Enabled	C,W	False		Enables transferring of the trend sample data to the Metasys Server when this attribute is set to True and the buffer fills to the level specified by the Transfer Setpoint attribute. If you create multiple trend extensions on a single point and send it to a Historical Data Repository, then setting Repository Enabled to true causes the Trend Viewer and/or Trend Study to display a combination of 15-minute and 1-minute samples. If Repository Enabled is set to False, then the Trend viewer displays only the data from the selected Trend Extension. To use multiple trends on a single object in a Historical Data Repository, create duplicate AV or BV objects that map to the point in question, then create a new trend on the parallel AV or BV.
Sample Interval	C,W	600	0–604,800 Units = Seconds	Specifies the periodic time in seconds for which the referenced property is logged. If this attribute is zero, samples are recorded using COV reporting. Notes: If you want to take samples on a COV, set the value of this attribute to 0 seconds. If you are not sampling on a COV, configure the Sample Interval at 60 seconds or higher to prevent loss of trend data and reduction in performance of the network engine and Metasys Server devices that receive samples from the configured trend.
Samples Not Sent to ADS		0	0–5,000	Represents the total number of samples requiring delivery to the Metasys Server repository during the next transfer.
Start Time	C,W			Specifies the time and date to enable logging when the Enable attribute is set to True. If the Start Time contains any wildcard values, then the conditions to enable logging based on time are ignored. When the Trend object is inactive due to the current time being outside of the Start Time or Stop Time, the Status attribute reflects this state (assuming it is the highest priority status). If you define a Stop Time that is before the Start Time, the Trend object is disabled.
Status Flags				Indicates the general status of the object in BACnet terms and contains four independent states. The four flags are: In Alarm—False if the Event State attribute value is Normal; otherwise, the In Alarm flag is True. (Set only by BACnet Intrinsic Alarming.) Fault—True (1) if the Reliability attribute is not reliable; otherwise, the Fault flag is False. Overridden—Overridden flag is True if the Present Value is overridden from the hardware source level. Out of Service—Out of Service flag is True if the Out of Service attribute value is True; otherwise, the Out of Service flag is False.
Stop Time	C,W			Specifies the time and date to disable logging. If the Stop Time contains any wildcard values, then the conditions to disable logging based on time are ignored. Logging is disabled if the Stop Time is prior to the Start Time. When the Trend object is inactive due to the current time being outside of the Start Time or Stop Time, the Status attribute reflects this state (assuming it is the highest priority status). A change in the active/inactive state due to the Start Time/Stop Time value has no impact on the Enable attribute. If the Trend object was disabled due to the Stop Time, the Trend object attempts to send the trend samples to the server. If you define a Stop Time that is before the Start Time, the Trend object is disabled.
Stop When Full	C,W	False		When set to False, logging continues. If the Repository Enabled attribute is set to False, the previously recorded samples are overwritten. If the Repository Enabled attribute is set to True and the buffer fills to the level specified by the Transfer Setpoint attribute, the previously recorded samples are sent to the . The buffer must be cleared for logging to continue. Specifies whether logging ceases when the buffer is full. When set to True, logging ceases and all accumulated samples remain in the buffer.
Total Record Count				Represents the total number of records collected by the Trend Extension since creation. When the value of Total Record Count reaches its maximum possible value of 0XFFFFFFFF, the next value it takes is zero. Once this value has wrapped to zero, its semantic value (the total number of records collected) is lost, but its use in generating notifications remains.
Transfer Setpoint	C,W	130 (90% of Buffer Size)	1–5,000	Represents the amount of buffer memory (in number of samples) that must fill before the trend extension requests a transfer of the current samples to the Metasys Server for permanent storage. The value cannot be greater than the buffer size when Repository Enabled is true.
Trigger	C,W			Causes the collection of data when changed from False to True, Enable is set to True, and the trend is within the Start/Stop times. When data collection completes, this attribute resets to False. This attribute does not trigger Johnson Controls COVs.