Averaging extensions - Metasys - LIT-12011953 - Server - Metasys UI

Averaging extensions - Metasys - LIT-12011953 - Server - Metasys UI - 7.0.50

Metasys UI Help

Product

Building Automation Systems > Graphics and Interfaces > Metasys UI

Document type

User Guide

Document number

LIT-12011953

Version

7.0.50

Revision date

2024-03-19

Product status

Active

The Averaging extension calculates the average, minimum, and maximum value of an attribute over a specific interval (for example, space temperature over 24 hours). The extension is able to sample Boolean, Integer, Unsigned, Enumerated, or Float attribute value types for any extendable objects within a BACnet device.

Averaging Extensions contain attributes common to Metasys system objects. The following table lists the attributes specific to the Averaging extension.

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. Averaging extension attributes
Attribute name	Notes	Initial value	Values/Options/Range	Description
Input Reference	C			Defines the object and attribute pair to be sampled. The sampled object must be on the same device as the Averaging object.
Max Value Timestamp		Invalid DateTime	If Average Value, Minimum Value, or Maximum Value is Unreliable, the timestamp is Undefined.	Indicates the date and time that the Maximum Value has changed in the sampling buffer.
Min Value Timestamp		Invalid DateTime	If Average Value, Minimum Value, or Maximum Value is Unreliable, the timestamp is Undefined.	Indicates the date and time that the Minimum Value has changed in the sampling buffer.
Object Property Ref				Designates the particular object and attribute referenced by the Averaging object. This is a BACnet Device Property Reference structure type attribute that specifies bind information from the object/attribute defined by the Input Reference attribute. The binding information consists of the Device Identifier, Object Identifier, Array Index, and Property Identifier of the trended property. An on-box object returns nothing for the Device Identifier. The Device Object configures this attribute during object creation. Changing Object Property Ref may change Input Ref, and changing Input Ref may change Object Property Ref. Since Object Property Ref is based on Input Ref, and Input Ref does not support Array Index, Object Property Ref does not support Array Index either.
Valid Samples				Indicates the number of samples in the sampling buffer that are valid. A sample is marked invalid if a read error occurs when reading requested attributes from the host object. The number of invalid samples can be determined by subtracting Valid Samples from Attempted Samples. If the difference is greater than zero, it indicates an error during sample collection. After Attempted Samples, Window Samples, or Window Interval is written, until a sample is taken, this attribute is set to zero.
If any of these variables are Unreliable and a BACnet read is performed on the following three attributes, the values returned are NaN for Average Value, -INF for Minimum Value, and INF for Maximum Value. If these values are Unreliable and a BACnet read is not performed, the attributes return zero.
Average Value	D,R	NaN	Units of the extended attribute	Indicates the sum of all valid samples in the sampling buffer divided by the number of samples in the buffer. This attribute is set to NaN with its Reliability set to Unreliable until a sample is taken and Attempted Samples, Window Samples, or Window Interval is written.
Maximum Value	R	-INF	Units of the extended attribute	Indicates the highest value of the valid samples in the buffer. After Attempted Samples, Window Samples, or Window Interval is written, until a sample is taken, this attribute is set to -INF with its Reliability set to Unreliable.
Minimum Value	R	INF	Units of the extended attribute	Indicates the lowest value of the valid samples in the buffer. After Attempted Samples, Window Samples, or Window Interval is written, until a sample is taken, this attribute is set to -INF with its Reliability set to Unreliable.
If any of the following three attributes are written or changed, all samples in the sampling buffer become invalid (set to zero, NaN, -INF, or INF), which makes them Undefined for the UI.
Attempted Samples	W		The only acceptable value that can be written to this property is zero using the Clear command.	Indicates the total number of samples in the buffer. The only acceptable number that can be written to this attribute is zero. After Window Samples or Window Interval is written, until a sample is taken, this attribute is set to zero.
Window Interval	C,W	3,600	Units = seconds Range: 900–360,060	Indicates the period of time in seconds over which the Minimum Value, Maximum Value, and Average Value are calculated. Samples are taken at a specific sample rate, which cannot be less than 4 seconds. The sample rate is calculated by dividing the Window Interval by the number of samples as defined in the Window Samples attribute. The default value is 3,600 seconds.
Window Samples	C,W	15	Range: 2–200	Indicates the sum of all valid samples in the sampling buffer divided by the number of samples in the buffer. This attribute is set to NaN with its Reliability set to Unreliable until a sample is taken and Attempted Samples, Window Samples, or Window Interval is written.
The following four attributes do not appear in a view, but may be scheduled, trended, and so on.
COV Increment	C,W	0.01	Any value > 0 Floating point value of the Display Precision.	This attribute does not appear in a view, but may be scheduled, trended, and so on. Specifies the minimum change in Present Value required for the object to report a change in the Average Value, Minimum Value, and Maximum Value attributes.
Display Precision	C,W	100ths	Uses Display Precision (Set 0).	Defines the decimal rounding and the decimal places to display for the Present Value and associated attributes. Average Value, Minimum Value, and Maximum Value use the same display precision. This attribute does not appear in a view, but may be scheduled, trended, and so on.
Reliability		Reliable	Uses Reliability (Set 503).	Indicates whether the Average Value, Minimum Value, and Maximum Value attributes are Unreliable. After Attempted Samples, Window Samples, or Window Interval is written, until a sample is taken, this attribute is set to Unreliable. This attribute does not appear in a view, but may be scheduled, trended, and so on.
Units		No Units	Units of the extended attribute	Indicates the units of the mapped attribute of the extended object. Average Value, Minimum Value, and Maximum Value use the same units. This attribute does not appear in a view, but may be scheduled, trended, and so on.

The following table lists the commands supported by the Averaging extension.

Table 2. Averaging extension commands
Command name	Parameters	Description
Enable	None	Clears the sampling buffer and restarts the sampling process. This command has the same effect as the Clear command.
Disable	None	Stops the sampling process.
Clear	None	Writes zero to the Attempted Samples attribute, clears the sampling buffer, and restarts the sampling process. This command has the same effect as the Enable command.