Multistate Value/ BACnet Multistate Value

Transcription

1 Object Dictionary 1 Multistate Value/ BACnet Multistate Value Introduction Note: The Johnson Controls Multistate Value object is considered a BACnet Multistate Value object because it supports BACnet functionality. In addition, this object has Johnson Controls proprietary attributes. The Multistate Value object s attributes represent the desired state of one or more physical outputs or processes of the device in which the object resides. The actual functions associated with a particular state are determined locally (not part of protocol). Present Value represents the state with a number and State Text associates a description with each state. Multistate Value objects have similar software characteristics and capabilities to an N2 Multistate Input object; however, Multistate Value objects are not associated with any physical hardware and are the result of a control process or operator entry. The Multistate Value object provides a means to map up to 256 different states to an object. This object allows you to hold a multistate value for other objects to reference. For example, a specific multistate value can be available for the Interlock object to reference and to base its operation on this value. See the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE) Standard for information on this object and the BACnet communication standard. May 1, 2002 Johnson Controls, Inc. Code No. LIT Software Release 5.1

2 2 Multistate Value/BACnet Multistate Value Attributes Specific Attributes Table 1: Attribute Properties The attributes specific to the Multistate Value object are listed in Table 1. The Multistate Value object also has the attributes of the Metasys Common object. Refer to Table 1 in the Metasys Common Object chapter (LIT ) for details. Attribute Name Data Type N30 M-Series N30 Default Value Options/Range Metasys Common Attributes See Table 1 in the Metasys Common Object chapter (LIT ). BACnet Required Attributes Event State Enumeration Normal Normal, Fault, Offnormal Number of States Object Identifier CW W 4 Minimum Value = 2 Maximum Value = 32 BACnet Object ID C Out of Service Boolean False Always False Present Value 2 Enumeration DNRW DNRW States Text attribute identifies Status Flags Bit String False, False, False, False BACnet Optional Attributes Acked Transitions 1 Bit String True, True, True Alarm Values 1 List of Short Continued on next page... In Alarm, Fault, Overridden, Out of Service See BAC Status Flags To-Offnormal, To-Fault, To-Normal See BAC Event Bits CW W States Text attribute identifies * C - Configurable, D - Default Attribute, N - Value Not Required, R - Association to Reliability, W - Writable 1 If the object supports intrinsic reporting, these attributes are required. 2 If Present Value is commandable, then it must be writable. If Out of Service is True, this attribute is True.

3 Object Dictionary 3 Attribute Name (Cont.) Data Type N30 M-Series N30 Default Value Options/Range BACnet Optional Attributes (Cont.) Event Enable 1 Bit String CW W True, True, True Event Time Stamps 2 Fault Values 1 Notification Class 1 Array Short Long To-Offnormal, To-Fault, To-Normal See BAC Event Bits CW W States Text attribute identifies CW W The BACnet Object Identifier of the Notification Class object used for routing Notify Type 1 Enumeration CW W Alarm Alarm, Event See BAC Notify Type Profile Name This BACnet optional attribute is not supported. Priority Array 3 Array Reliability 4 Enumeration W W Reliable No Fault Detected (Reliable), Multi State Fault, Unreliable Other See Reliability Enumeration Set in Relinquish Default 3 Enumeration CW W State 0 States Text attribute identifies State Text Time Delay 1 Intrinsic Alarming Array of Strings Short Off Low Med Hi See States Text in. CW W 0 Units = seconds Johnson Controls Proprietary Attributes Boolean C False False True States Text Enumeration CW W States See States Text in * C - Configurable, W - Writable 1 If the object supports intrinsic reporting, these attributes are required. 2 If Present Value is commandable, then it must be writable. If Out of Service is True, this attribute is True. 3 If Present Value is commandable, both these attributes are present. 4 The Reliability attribute is always present in N30 implementations.

4 4 Multistate Value/BACnet Multistate Value Attribute Definitions Table 2: Attribute Definitions Attribute Name Metasys Common Attributes Event State Number of States Object Identifier Out of Service Present Value Table 2 lists the definitions of the attributes specific to the Multistate Value object. Definition See Table 2 in the Metasys Common Object chapter (LIT ). BACnet Required Attributes Indicates if an active event state is associated with the object. If the object supports intrinsic reporting, this attribute indicates the event state of the object. If not, the attribute is Normal. Defines the number of states possible for Present Value. Identifies the object with a unique numeric code. Indicates the offline/online state of the connected hardware. This attribute exists for compatibility with BACnet protocol and indicates whether the physical input that the object represents is in service. When out of service, the object does not read the hardware. This attribute is always False. Reflects the current value of the multistate value object as one of n states, where n is the number of states defined in the Number of States The Present Value is equal to the last value corresponding to the States Text Present Value is optionally commandable. If Present Value is commandable for a given object instance, then Priority Array and Relinquish Default are also present for that instance. If Out of Service is True, Present Value is writable. Status Flags Contains four Boolean flags that indicate the general health of the object. Three of the four flags are associated with the values of other attributes within the same object. By reading these attributes, you get a clearer picture of the object status. The four flags are: In Alarm - In Alarm flag is False (0) if the Event State property value is Normal; otherwise the In Alarm flag is True (1). Fault - Fault flag is True (1) if the Reliability attribute is not reliable; otherwise the Fault flag is False (0). Overridden - Overridden flag is Logical 1 if the Present Value has been overridden by some mechanism local to the BACnet device or because operator intervention provided a different value. 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. Continued on next page...

5 Object Dictionary 5 Attribute Name (Cont.) Acked Transitions Alarm Values Event Enable Event Time Stamps Fault Values Notification Class Notify Type Definition BACnet Optional Attributes Conveys three flags that separately indicate the receipt of acknowledgements for To-Offnormal, To-Fault, and To-Normal events. These flags clear upon the occurrence of the corresponding event and set under any of these conditions: upon receipt of the corresponding acknowledgement upon the occurrence of the event if the corresponding flag is not set in the Event Enable attribute (meaning event notifications are not generated for this condition and, thus, no acknowledgement is expected) upon the occurrence of the event if the corresponding flag is set in the Event Enable attribute and the corresponding flag in the Ack Required attribute of the Notification Class object implicitly referenced by the Notification Class attribute of this object is not set (meaning no acknowledgement is expected) This attribute is required if intrinsic reporting is supported by this object. Specifies any states that the Present Value must equal before a To-Offnormal event generates. If the object supports intrinsic reporting, this attribute is required. A To-Offnormal event generates under these conditions: Present Value equals at least one of the values in the Alarm Values list, and Present Value remains equal to the same value for a minimum period of time, specified by Time Delay the To-Offnormal flag is enabled in Event Enable Once equal to the Alarm Values, Present Value must become not equal to any of the states in this attribute and not equal to any of the states in the Fault Values attribute before a To-Normal event generates under these conditions: Present Value must remain not equal to any of the states in Alarm Values attribute for a minimum period of time, specified by Time Delay Present Value must remain not equal to any of the states in Fault Values the To-Normal flag must be enabled in Event Enable Conveys three flags that separately enable and disable reporting of To-Offnormal, To-Fault, and To-Normal events. An unreliable condition generates a Fault event. This attribute is required if the object supports intrinsic reporting. Conveys the times of the last To-Offnormal, To-Fault, and To-Normal event notifications, respectively. Time or Date time stamps have FF in each octet. Sequence time stamps are 0 if no event notification of that type has been generated. This attribute is required if the object supports intrinsic reporting. Specifies any states that the Present Value must equal before a To-Fault event generates. If Present Value equals any of the states in the Fault Values list, and no physical fault is detected for any inputs or outputs Present Value represents, Reliability has the value Multi State Fault. If the object supports intrinsic reporting, this attribute is required. Specifies the notification class used when handling and generating event notifications for the object. This attribute implicitly refers to the Notification Class object that has a Notification Class attribute of the same value. This attribute is required if the object supports intrinsic reporting. Conveys whether the notifications generated by the object are Events or Alarms. This attribute is required if the object supports intrinsic reporting. Priority Array Contains prioritized commands that are in effect for this object. See the BACnet standard for a description of the prioritization mechanism. If either Priority Array or Relinquish Default are present, both are present. If Present Value is commandable, Priority Array and Relinquish Default are both present. Continued on next page...

6 6 Multistate Value/BACnet Multistate Value Attribute Name (Cont.) Reliability Relinquish Default State Text Time Delay Intrinsic Alarming States Text Definition BACnet Optional Attributes (Cont.) Indicates if the Present Value is reliable and why. If Fault Values is present, Reliability is also present. A To-Fault event generates under these conditions: Reliability is not equal to No Fault Detected the To-Fault flag is enabled in Event Enable Indicates the default value used for Present Value when all command priority values in Priority Array are Null. If either Relinquish Default or Priority Array is present, both of them are present. If Present Value is commandable, Priority Array and Relinquish Default are both present. Represents descriptions of all possible states of Present Value. The number of descriptions matches the number of states defined in Number of States. Present Value (an integer) serves as an index into the array. Specifies the minimum number of seconds that Present Value remains: equal to any one of the values in Alarm Values before a To-Offnormal event generates not equal to any of the values in Alarm Values before a To-Normal event generates If the object supports intrinsic reporting, this attribute is required. Johnson Controls Proprietary Attributes Enables the definition of the intrinsic alarm related attributes. Indicates the displayed strings for the Present Value.

7 Object Dictionary 7 Commands The Multistate Value object supports the commands listed in Table 3. The order of the commands in the table reflects how the commands appear on the user interface. Table 3: Supported Commands Command Name Parameters Access Level Description State0... StateN Operate Releases Command Priorities 9 through 15 (Scheduling) and then writes to the Present Value at the Default (16) command priority. The state command names and number of commands are dependent on the States Text and Number of States attributes. Override State0-StateN Supervise Updates the Present Value at Command Priority Operator Override. Override Release Supervise Releases Command Priority Operator Override from Present Value. Release 1. Attribute name Modify Releases the identified command priority 2. Command from the specified, writable attribute, and priority allows it to be controlled by the next highest priority. Release All Attribute name Modify Releases Command Priorities 3 through 15 from the specified, writable Command Priorities 1 and 2 remain. Enable Modify Allows distribution of Changes-of-Value and commanding. Disable Modify Prevents distribution of Changes-of-Value and commanding. Controls Group 507 E. Michigan Street P.O. Box 423 Milwaukee, WI Printed in U.S.A.