RedundantDIObject

The RedundantDIObject provides you with the ability to configure a single object with connections to two different data sources (proxy objects or DIDevice objects). In the event of a failure of the active data source, this object automatically switches to the standby data source.

This capability allows clients to configure redundant connections to a field device.

Click one of the following Help topics to navigate to information about that topic.

Overview

The RedundantDIObject is a DeviceIntegration object that makes redundant connections to a field device possible. If one of the source objects is unable to provide connection to the field device, the RedundantDIObject automatically switches to the other source object for continued data acquisition.

Topic Category	Topic Subcategory	Topic Details
Overview
Configuration	General Configuration	Scan Group Configuration
Block Read Configuration
Run-Time Behavior
Object Attributes	Alarm Aggregation Attributes

the ConnectionStatus attribute, common to all DIObjects, is Disconnected,

the ProtocolFailureReasonCode attribute is non-zero, indicating a failure in communication between a DAS DIObject and a field device,

the ScanState attribute, common to all ApplicationObjects, is Offscan, or

the Scan-Group Ping-Item status of the active source is not as good as the Scan-Group Ping-Item status of the standby source.

When the active data source is in a Bad state, a switchover attempt is made to the standby data source.

There is a one-to-two relationship between an instance of a RedundantDIObject and a pair of source DeviceIntegration objects.

The RedundantDIObject supports the following operations on I/O points from field devices:

Subscriptions, which are implemented via scan groups. For more information, see Scan Group Configuration.

Read transactions, which are implemented via block reads (when available in the source DIObject). For more information, see Block Read Configuration.

Write transactions, which are implemented via block writes (when available in the source DIObject). For more information, see Block Write Configuration.

Most ApplicationObjects in the ArchestrA environment write only the last data received in a scan cycle. DeviceIntegrationObjects, including the RedundantDIObject, operate differently. They queue all data received in a scan cycle and write them all in the order received.

If the quality of an attribute changes, but a new value is not received from the data provider, the current time is used to update the time stamp of the attribute.

The two source DIObjects do not have to be the same type. But they must support the same type of DAGroups and must have the same item address space.

Important! The RedundantDIObject checks the state of its source DIObjects on every scan cycle.

During configuration, one DIObject is set as the Primary DI source and the other is set as Backup DI source. These are just the starting points. During runtime, the terms Active and Standby apply, the configured Primary object initially being the Active object (if able to provide connection to the field device) and the configured Backup object initially being the Standby. If the connection to the Active object fails, then the Standby becomes the Active one and the other becomes the Standby. This switching between Active and Standby objects can be repeated multiple times depending on the configured switch attributes.

For complete redundancy coverage, the RedundantDIObject must be configured to have the DAGroups that are common to both source DIObjects. When the connection fails to the Active DIObject, all items are unsubscribed from the Active DIObject and new subscriptions are made to the Standby DIObject. If either DIObject has unique DAGroups, it is important that the RedundantDIObject should not be configured to use those uncommon DAGroups.

For more information about this object and its place in the ArchestrA redundancy infrastructure as well as general information on objects, including relationships, deployment, and alarm distribution, see the Integrated Development Environment (IDE) documentation. You can access the IDE Help (IDE.chm) from within the IDE by clicking Help Topics on the Help menu.

Configuration

This configuration section describes the object editor options for configuration and the associated attributes.

Topic Category	Topic Subcategory	Topic Details
Configuration	General Configuration	Scan Group Configuration
Block Read Configuration

This object Help file does not include information about extensibility options that are common to all objects. For information on configuration options for the Object Information, Scripts, Attributes, and Graphics tabs, see the Configuration Help. To access this Help file, click the Configuration Help link, which is located in the fixed header area that appears at the top of this Help file window.

General Configuration

Use the General tab to configure and tune the behavior of the RedundantDIObject.

Options are as follows. For more information about the attribute associated with each option, click the attribute link in parentheses.

The name of the Primary DIObject for establishing I/O connectivity with the field device. Use the drop-down button to display a list of object instances whose object type is either DINetwork or DIDevice. The name of the Primary DI Source must be different from the Backup DI Source.

The name of the Backup DIObject for establishing I/O connectivity with the field device should the Primary DIObject fails. Use the drop-down button to display a list of object instances whose object type is either DINetwork or DIDevice. The name of the Backup DI Source must be different from the Primary DI Source.

Enables a connection alarm, which is raised if the connection is lost to both Active and Standby DIObject sources or when the SwitchCnt attribute reaches the Switch attempts value. Default is disabled.

Sets connection alarm priority. Valid values are 1 through 999, with 1 being the most urgent. Default value is disabled, 500 if the Detect connection alarm option is enabled.

The maximum number of switches allowed between Active and Standby DIObjects. Default value is unlimited (-1). Only integer values are valid. Minimum value is -1 (unlimited switches), zero means switch is not allowed, and all other integer values represent the total number of switches allowed. The attribute that tracks the number of switches between Active and Standby DIObjects is SwitchCnt. When SwitchCnt reaches the value of SwitchMax, the ConnectionAlarm is set, and no more switches are allowed until SwitchCnt is reset.

Sets the security classification for the capability to reset to zero the SwitchCnt attribute, which represents the number of times the RedundantDIObject has switched from Active to Standby DIObject data sources. It also resets the switchover alarm to false.

Enables an alarm if the connection is switched from the Active DIObject to the Standby DIObject. Default is disabled.

Sets switchover alarm priority. Valid values are 1 through 999, with 1 being the most urgent. Default is disabled, 500 if the Detect switchover alarm option is enabled.

Sets the security classification for the capability to cause a failover operation, the process of switching between the Active and Standby DIObjects. Default setting is Operate.

Scan Group Configuration

Use the Scan Group tab to configure one or more scan groups. A scan group, or device group, contains items that will be polled according to a specified update interval.

The update interval for each scan group is inherited from the scan groups configured in the source DIObjects.

The item references for each attribute are not copied. Instead item references are resolved by the Primary and Backup DIObject data sources. If aliases are used, both source DIObjects must support the same set of alias names.

Note You must configure at least one scan group before you can deploy the RedundantDIObject.

Click the Copy Common Scan Groups button to display the dialog box displayed below. This dialog box shows the scan groups configured in the Primary DIObject (Configured in primary) and the Backup DIObject (Configured in backup), and those scan groups shared by the two DIObjects (Identically named). Click OK to add the scan groups in the Identically named box to the Available scan groups list on the Scan Group tab.

Important! Only scan groups shared by the Primary and Backup DIObjects should be configured in the RedundantDIObject. If you include non-shared groups, the RedundantDIObject will be placed in Warning state. If you configure non-shared groups in the RedundantDIObject first, you can add them to either DIObject source at a later time. You then must validate the RedundantDIObject to change it from Warning state to Good state. A special case is the unnamed Scan Group that is preconfigured in all DAS DIDevice Objects and in the InTouchProxy object. The unnamed Scan Group is represented in the RedundantDIObject editor as <Default>.

To configure additional scan groups, click the Add ("+" sign) button to start filling in a new group. To delete a row from a list, select the row and then click the Delete ("X" sign) button.

To add attributes to the Associated attributes list, select a scan group and click either the Copy Attributes from Primary or Copy Attributes from Backup button. All configured attributes from the respective DIObject sources (corresponding to the selected Scan Group) are added to the Associated attributes list (only attribute names).

To configure additional attributes for a scan group, use the Add ("+" sign) and Delete ("X" sign) buttons. The maximum number of attributes that can be preconfigured is 5,000 per Scan Group. You do not have to add attributes to a scan group; you can simply define the scan group and reference the device items directly from the client. Scan group attributes are simply named placeholders for values coming from the associated field device items. To reference attributes or items in a scan group that you create, you must include the scan group name in the reference.

Valid characters for scan group and attribute names include all alphabetic characters (A-Z, a-z), and/or numeric digits (0-9), and/or the following special characters: the underscore (_), the dollar sign ($), and the pound sign (#). Spaces are not allowed.

Run-time object attributes allow you to monitor scan group errors and other diagnostic information.

Options are as follows. For more information about the attribute associated with each option, click the attribute link in parentheses.

The list of names of all configured scan groups (special case is the unnamed Scan Group which is represented by a blank space). When a set is made with new values, it should contain a unique name for the scan group, from which data will be received. Group names should be unique across ScanGroupList, BlockReadList and BlockWriteList.

The item quality of this item is checked on each scan to determine the Scan Group status.

This list contains all of the attributes that are configured for the selected scan group.

Block Read Configuration

Use the Block Read tab to configure one or more block read groups. A block read group is a set of items for which values will be read from the field device in a single transaction. Each block read group configured within this object can be named <Block Name.>.

Note Transaction timeouts and access paths for block read groups are inherited from the block read groups configured in the source DIObjects. The item references for each attribute are not copied. Instead item references are resolved by the Primary and Backup DIObject data sources. If aliases are used, both source DIObjects must support the same set of alias names.

Instead of the I/O points being on advise, as with a scan group, the attributes are updated once per transaction with the values from the item references. A block read transaction must be initiated from a user or script via the TransactionTrigger attribute.

In the case of a block read failure or transaction timeout, the RedundantDIObject would forcefully complete the transaction and set the data quality of incomplete items to BAD.

Click the Copy Common Block Reads button to display the dialog box displayed below. This dialog box shows the block read groups configured in the Primary DIObject (Configured in primary) and the Backup DIObject (Configured in backup), and those block read groups shared by the two DIObjects (Identically named). Click OK to add the block read groups in the Identically named box to the Available block reads list on the Block Read tab.

Important! Only block read groups shared by the Primary and Backup DIObjects should be configured in the RedundantDIObject. If you include non-shared groups, the RedundantDIObject will be placed in Warning state. If you configure non-shared groups in the RedundantDIObject first, you can add them to either DIObject source at a later time. You then must validate the RedundantDIObject to change it from Warning state to Good state.

To configure additional block read groups, click the Add ("+" sign) button to start filling in a new group. To delete a row from a list, select the row and then click the Delete ("X" sign) button.

To add attributes to the Associated attributes list, select a block read group and click either the Copy Attributes from Primary or Copy Attributes from Backup button. All configured attributes from the respective DIObject sources (specific to the selected Block Read) are added to the Associated attributes list.

To configure additional attributes for a block read group, use the Add ("+" sign) and Delete ("X" sign) buttons.

Valid characters for block read group and attribute names include all alphabetic characters (A-Z, a-z), and/or numeric digits (0-9), and/or the following special characters: the underscore (_), the dollar sign ($), and the pound sign (#). Spaces are not allowed.

Run-time object attributes allow you to monitor transaction errors and other diagnostic information.

Note Although block reads are intended to be individual transactions, the actual communication with the field device is dependent on the number and type of attributes, and it may be necessary to send and receive multiple messages to and from the field device. As a result, the values exposed after a block read operation might have been obtained at different times. You must carefully design the logic in the field device to make sure that the values do not change until the full read operation is completed.

Options are as follows. For more information about the attribute associated with each option, click the attribute link in parentheses.

The list of names of all configured block read groups. When a set is made with new values, it should contain a unique name for the block read group, from which data will be received. Group names should be unique across ScanGroupList, BlockReadList, and BlockWriteList.

This list contains all of the attributes that are configured for the selected block read group.

Block Write Configuration

Use the Block Write tab to configure one or more block write groups. A block write group is a set of items for which values will be written to the field device in a single transaction. Each block write group configured for this object can be named <Block Name.>.

Note Transaction timeouts and access paths for block write groups are inherited from the block write groups configured in the source DIObjects. The item references for each attribute are not copied. Instead item references are resolved by the Primary and Backup DIObject data sources. If aliases are used, both source DIObjects must support the same set of alias names.

Only values that are new for the attribute since the last transaction are written to the field device. A block write transaction must be initiated from a user or script via the TransactionTrigger attribute. You cannot trigger another transaction if the previous transaction has not completed.

Partial writes are supported. However, the system does not offer roll-back functionality. In the case of a block write failure or transaction timeout, some values may have been successfully sent, but there is no way to undo the value changes. For items that have not yet been written to, the data quality is set to BAD.

Click the Copy Common Block Writes button to display the dialog box displayed below. This dialog box shows the block write groups configured in the Primary DIObject (Configured in primary) and the Backup DIObject (Configured in backup), and those block write groups shared by the two DIObjects (Identically named). Click OK to add the block write groups in the Identically named box to the Available block writes list on the Block Write tab.

Important! Only block write groups shared by the Primary and Backup DIObjects can be configured in the RedundantDIObject. If you include non-shared groups, the RedundantDIObject will be placed in Warning state, and you cannot deploy the object. If you configure non-shared groups in the RedundantDIObject first, you can add them to either DIObject source at a later time. You then must validate the RedundantDIObject to change it from Warning state to Good state.

To configure additional block write groups, click the Add ("+" sign) button to start filling in a new group. To delete a row from a list, select the row and then click the Delete ("X" sign) button.

To add attributes to the Associated attributes list, select a block write group and click either the Copy Attributes from Primary or Copy Attributes from Backup button. All configured attributes from the respective DIObject sources (specific to the selected Block Write) are added to the Associated attributes list.

To configure additional attributes for a block write group, use the Add ("+" sign) and Delete ("X" sign) buttons.

Valid characters for block write group and attribute names include all alphabetic characters (A-Z, a-z), and/or numeric digits (0-9), and/or the following special characters: the underscore (_), the dollar sign ($), and the pound sign (#). Spaces are not allowed.

Run-time object attributes allow you to monitor transaction errors and other diagnostic information.

Note Although block writes are intended to be individual transactions, the actual communication with the field device is dependent on the number and type of attributes, and it may be necessary to send and receive multiple messages to and from the field device. In the case of a block write operation, the logic in the field device must not use the written values until the full write operation is completed.

Options are as follows. For more information about the attribute associated with each option, click the attribute link in parentheses.

The list of names of all configured block write groups. When a set is made with new values, it should contain a unique name for the block write group, from which data will be received. Group names should be unique across ScanGroupList, BlockReadList and BlockWriteList.

This list contains all of the attributes that are configured for the selected block write group.

Run-Time Behavior

Run-time behavior pertains to the running state of a deployed object. Once deployed and operating, the RedundantDIObject can assume one of the following states:

Startup. This state describes the operations performed by the object when the object is being initialized. The RedundantDIObject begins tracking whether the target DIObjects are deployed and onscan, the ConnectionStatus is connected, subscribes to the configured Ping Items on each data source, and checking for a non-zero ProtocolFailureReasonCode. Data acquisition has not been started yet.

Going onscan. This state describes the operations performed by the object when it is about to start the data acquisition process. Reading and writing to data items in the low-level device will immediately follow. All dynamic attributes requested by clients are subscribed to. The object will go into the Continuous execution state.

Continuous execution. This state describes the operations when the object is running. In this state, the RedundantDIObject:

Adds newly activated attributes to the Active DI source. If the ScanMode is set to ActiveOnDemand, adds the attributes in an inactive state to the backup DI source. Otherwise, the attributes are added in an Active state.

Updates attributes with new values if new data comes from the Active DI source.

Services read and write requests.

Monitors the connection to the Active and Standby DI sources. If the connection to the Active fails, it switches to the Standby. Also updates the DISourceActive, DISourceStandby, StatusPrimaryDISource, StatusBackupDISource attributes. When switchover occurs, it updates the SwitchTime, SwitchTimePrevious, SwitchReason, SwitchReasonPrevious, SwitchCnt, and SwitchAlarm attributes.

Monitors the item quality of the ping items in all scan groups in both the Active and Standby sources. When no ping item is specified for a scan group, the first item in the scan group requested by a client is used as the ping item.

Detects alarm conditions, if alarming is enabled.

Raises a connection alarm if connection to both DI sources fails or when the SwitchCnt attribute’s value reaches the SwitchMax attribute’s value. The connection alarm will be reset to false automatically when the connection to one of the DI sources is restored.

Monitors the data quality for DIObject data values and updates run-time error statistics if the quality is not Good.

Going offscan. This state describes the operations performed by the object when it is about to stop its data acquisition process. Reading and writing to data items in the low-level device will immediately stop. The object is set to offscan state and it unsubscribes to all dynamic attributes in all DAGroups. The object is going out of the Continuous execution state. The ConnectionStatus attribute is set to "Disconnected."

Shutdown. This state describes the operations performed by the object when it is about to clean up its data connections and then stops the data acquisition process.

Special set handling. This state describes the special operations supported by the object when it is set (written to). These operations include:

Setting DISourcePrimary attribute - You can change the primary DI source at runtime. If the primary DI source is currently the active DI source, a switchover occurs. All items that were currently subscribed are removed, all transactions in progress are forcefully completed, and the quality of the items not processed is set to Bad. The same subscriptions are made to the new Active DI source and all attributes are updated.

Setting DISourceBackup attribute - You can change the backup DI source at runtime. If the backup DI source is currently the active DI source, a switchover occurs. All items that were currently subscribed are removed, all transactions in progress are forcefully completed, and the quality of the items not processed is set to Bad. The same subscriptions are made to the new Active DI source and all attributes are updated.

Setting SwitchReset attribute - You can reset the SwitchCnt attribute to zero (0) and the SwitchoverAlarm.Alarmed attribute to false by setting the SwitchReset attribute to True.

Setting SwitchMax - You can reset the SwitchMax attribute to a new value. Switch is not limited when this value is -1. Switch is not allowed when this value is zero (0).

Setting ForceFailoverCmd attribute - You can trigger a switchover between Active and Standby DI sources by setting ForceFailoverCmd to True. Switchover only occurs if the SwitchMax attribute has not been reached previously or if the SwitchMax value is -1. Also, if the Standby DI source is in Bad state, no switchover occurs. If a Force-Failover is completed successfully, SwitchoverAlarm.Alarmed is set to true, SwitchCnt is incremented, SwitchReason is set to "ForceFailover", and SwitchTime, SwitchTimePrevious and SwitchReasonPrevious are updated. DISourceActive and DISourceStandby attributes are also updated.

Time propagation. When the RedundantDIObject object receives a data update from the active DI source, the time stamp received is used to update the attribute. When the RedundantDIObject object receives a poke request, it forwards the poke request that contains the value and time stamp to the active DI source.

Object Attributes

The following table describes the RedundantDIObject’s attributes. These attributes are provided to optimize the performance of the RedundantDIObject and should be reserved for advanced users.

Topic Category	Topic Subcategory	Topic Details
Object Attributes	Alarm Aggregation Attributes

Attributes that are common to all objects are not included in the following attribute table. For information on common attributes, see the Configuration Help. To access this Help file, click the Configuration Help link, which is located in the fixed header area that appears at the top of this Help file window.

Hidden attributes are not included in the following attribute table. Hidden attribute names are prefixed with an underscore ( _ ) and may be visible within certain applications, such as the Object Viewer. Hidden attributes are generally used for internal ArchestrA functionality, and should be ignored.

The Config column specifies whether the attribute can be configured using an option in the object editor.

The RT Access column describes how the attribute value can be accessed at run time. Values for this column include:

Supervisory – The attribute value can be changed using a script.

User – The attribute value can be modified by the user.

Read-Only – The attribute value cannot be changed.

None – The feature is being deployed; however, the attribute is not deployed at run time (package only).


Attribute	Description	Config	RT Access
AlarmDSCnt	The total number of disabled and silenced alarms in the object. Sub-areas or sub-notification-distributors are not included.	No	Read-Only
AlarmInhibit	This attribute, when true, disables alarms in the RedundantDIObject.	No	Read-Only
AlarmMode	Contains the current alarm mode of the RedundantDIObject. The mode is based on the object's commanded mode if its area and container are enabled. Otherwise, the most disabled state of the container or parent area applies. "Disabled" is considered the most disabled mode, then "silenced," and then "enabled."	No	Read-Only
AlarmModeCmd	Currently commanded alarm mode of the RedundantDIObject.	No	Read-Only
AlarmOnCnt	The number of active alarms in the distributor. Does not include sub-areas or sub-notification-distributors.	No	Read-Only
AlarmUnAckCnt	The number of unacknowledged alarms in the distributor (including unacknowledged return-to-normal). Does not include sub-areas or sub-notification-distributors.	No	Read-Only
<Block Name.>AccessPath	The address path (maps to scan group). The path syntax is specific to the type of DIObject data source. This attribute reflects the same attribute value in the current Active DI source.	No	None
<Block Name.>AliasDatabase	Used to store pairs of alias attribute names and the corresponding item references. Item references are not editable in the RedundantDIObject. At run time, each item reference will reflect the same item reference value in the current Active DI source.	No	Read-Only
<Block Name.>ItemCnt	The total number of items in the group that are on advise by a client application.	No	Read-Only
<Block Name.>ItemErrorCnt	The current number of items within the group that have data quality other than GOOD. This value is calculated.	No	Read-Only
<Block Name.>ItemErrorCntAlarm	If TRUE, the current error count is not zero. This value can be alarmed.	No	Read-Only
<Block Name.>ItemErrorCntLast	The error count immediately prior to the current error count.	No	Read-Only
<Block Name.>ItemErrorCntLastEnd	The last time the error count returned to zero. The date format reflects the current locale setting for the operating system.	No	Read-Only
<Block Name.>ItemErrorCntLastStart	The last time that the error count changed from zero to non-zero, not including the most recent change. The date format reflects the current locale setting for the operating system.	No	Read-Only
<Block Name.>ItemErrorCntStart	The time that the error count most recently changed from zero to non-zero. The date format reflects the current locale setting for the operating system.	No	Read-Only
<Block Name.>ItemList	The list of user-defined names for item references. Normally, use the "Copy Attributes..." buttons to copy attributes from either of the DI source objects.	Yes	None
<Block Name.>StatsReset	If TRUE, reset all statistics during run time.	No	Supervisory, User
<Block Name.>TransactionComplete	If TRUE, the transaction has completed.	No	Read-Only
<Block Name.>TransactionEnd	The time the last transaction ended. The date format reflects the current locale setting for the operating system.	No	Read-Only
<Block Name.>TransactionsCnt	The total number of transactions since the last statistics reset.	No	Read-Only
<Block Name.>TransactionStart	The time the last transaction started. The date format reflects the current locale setting for the operating system.	No	Read-Only
<Block Name.>TransactionStatus	The status of the transaction. Valid values are: InActive, Processing, and Completed.	No	Read-Only
<Block Name.>TransactionTimeAvg	The average amount of time required to process this group since the last statistics reset.	No	Read-Only
<Block Name.>TransactionTimeMax	The longest amount of time required to process this group since the last statistics reset.	No	Read-Only
<Block Name.>TransactionTimeMin	The shortest amount of time required to process this group since the last statistics reset.	No	Read-Only
<Block Name.>TransactionTimeout	The amount of time, in milliseconds, allowed for the block transaction to complete. If this value is 0, then there is no transaction timeout. The default value is 0. This attribute reflects the same attribute value in the current Active DI source.	No	None
<Block Name.>TransactionTimeoutAlarm	If TRUE, the transaction timeout has been exceeded.	No	Read-Only
<Block Name.>TransactionTrigger	If TRUE, the transaction will be started.	No	Supervisory, User
BlockReadList	The list of names of all configured block read groups. When a set is made with new values, it should contain a unique name for the block read group, from which data will be received.	No	None
BlockWriteList	The list of names of all configured block write groups. When a set is made with new values, it should contain a unique name for the block write group, from which data will be received.	No	None
ConnectionAlarm	If set to TRUE, one of the following has occurred: both DI source objects are in Bad state or the SwitchMax value has been reached.	Yes	Read-Only
ConnectionStatus	The status of the connection between the object and the Active DIObject data source. Possible values are Connected and Disconnected. Disconnected means both DI source objects are in Bad state, the Active DI source is in Bad state and no switchover can occur because SwitchMax has been reached, or the object is set to Offscan. If none of these has occurred, this attribute’s value is Connected.	No	Read-Only
DISourceActive	Contains the name of the current Active DIObject data source.	No	Read-Only
DISourceBackup	Contains the name of the DIObject that is configured as the backup source of I/O points.	Yes	Supervisory, User
DISourcePrimary	Contains the name of the DIObject that is configured as the primary source of I/O points.	Yes	Supervisory, User
DISourceStandby	Contains the name of the current standby DIObject data source.	No	Read-Only
ForceFailoverCmd	Trigger for causing a failover operation, the process of switching between the Active and Standby DIObjects. This operation occurs only if the Switch attempts count has not been reach or if the Switch attempts value is -1 (unlimited switches).	Yes	Supervisory, User
InAlarm	Contains the RedundantDIObject’s alarm state. It represents the alarm condition, except when alarming is disabled (in which case InAlarm is set to Off).	No	Read-Only
PingItems	A string containing ScanGroupName,PingItem pairs	Yes	Read-Only
<Scan Group Name.>Active	If set to TRUE, the object will register all of the data items in the group. If FALSE, all attributes in the scan group will be unregistered.	No	Supervisory, User
<Scan Group Name.>ItemCnt	The total number of items in the group that are on advise by a client application.	No	Read-Only
<Scan Group Name.>ItemErrorCnt	The current number of items within the group that have data quality other than GOOD. This value is calculated.	No	Read-Only
<Scan Group Name.>ItemErrorCntAlarm	If TRUE, the current error count is not zero. This value can be alarmed.	No	Read-Only
<Scan Group Name.>ItemErrorCntLast	The error count immediately prior to the current error count.	No	Read-Only
<Scan Group Name.>ItemErrorCntLastEnd	The last time the error count returned to zero. The date format reflects the current locale setting for the operating system.	No	Read-Only
<Scan Group Name.>ItemErrorCntLastStart	The last time that the error count changed from zero to non-zero, not including the most recent change. The date format reflects the current locale setting for the operating system.	No	Read-Only
<Scan Group Name.>ItemErrorCntStart	The time that the error count most recently changed from zero to non-zero. The date format reflects the current locale setting for the operating system.	No	Read-Only
<Scan Group Name.>ItemList	The list of user-defined names for item references. Normally, use the "Copy Attributes from Primary" or "Copy Attributes from Backup" buttons to copy attributes from either of the DI source objects.	Yes	None
<Scan Group Name.>ItemUpdateCnt	The number of items whose values were updated during the most recent scan cycle. For the RedundantDIObject, the value of this attribute is always equal to ItemCnt. To get the actual ItemUpdateCnt value from the field device, subscribe to the ItemUpdateCnt attribute of the Active source DIObject.	No	Read-Only
<Scan Group Name.>PingItem	Name of item used to monitor the connection status between the DI source object and the PLC device	No	Read-Only
<Scan Group Name.>ScanMode	The scanning mode for the scan group, either ActiveOnDemand, Active, or ActiveAll. For the ActiveOnDemand mode, attributes that are not actively being referenced by any client or object are not scanned. For the Active mode, an attribute is always in the active scanning state. When the last reference to the attribute is unregistered (unadvised) , the attribute is deleted. For ActiveAll, an attribute is always in the active scanning state, but when the last reference to the attribute is unregistered (unadvised), the attribute is not deleted.	No	Supervisory, User
<Scan Group Name.>UpdateRateCmd	The rate, in milliseconds, at which the object will receive updated data values for the Scan Group. This attribute reflects the same attribute value in the current Active DI source.	No	None
ScanGroupList	The list of names of all configured scan groups. When a set is made with new values, it should contain a unique name for the scan group, from which data will be received.	No	Read-Only
StatusBackupDISource	Contains the current status of the backup DIObject as observed from the RedundantDIObject. Possible values are Connected, Disconnected, Offscan, Unknown: Config Error (DISource not accessible), and Unknown: Comm Error (DISource not accessible). Unknown indicates the RedundantDIObject cannot communicate with the backup DIObject and therefore cannot provide its status.	No	Read-Only
StatusPrimaryDISource	Contains the current status of the primary DIObject as observed from the RedundantDIObject. Possible values are Connected, Disconnected, Offscan, Unknown: Config Error (DISource not accessible), and Unknown: Comm Error (DISource not accessible). Unknown indicates the RedundantDIObject cannot communicate with the primary DIObject and therefore cannot provide its status.	No	Read-Only
SwitchCnt	The number of times the RedundantDIObject has switched from Active to Standby DIObject data sources.	No	Read-Only
SwitchMax	The maximum number of switches allowed between Active and Standby DIObjects. Default value is unlimited (-1). Only integer values are valid. Minimum value is -1 (unlimited switches), zero means switch is not allowed, and all other integer values represent the total number of switches allowed before the ConnectionAlarm is raised. The attribute that tracks the number of switches between Active and Standby DIObjects is SwitchCnt. When SwitchCnt reaches the value of SwitchMax, the ConnectionAlarm is raised, and no more switches are allowed until SwitchCnt is reset.	Yes	Supervisory, User
SwitchoverAlarm	Alarm raised whenever a switchover occurs.	Yes	Read-Only
SwitchReason	Contains the reason for the last switch between Active and Standby DI sources. Possible values are Disconnected, Offscan, ForceFailover, ActiveDISourceChanged, Unknown: Config Error (DISource not accessible), and Unknown: Comm Error (DISource not accessible).	No	Read-Only
SwitchReasonPrevious	Contains the reason for the previous switch between Active and Standby DI sources. Possible values are Disconnected, Offscan, ForceFailover, ActiveDISourceChanged, Unknown: Config Error (DISource not accessible), and Unknown: Comm Error (DISource not accessible).	No	Read-Only
SwitchReset	Trigger that sets the SwitchCnt attribute to zero (0) and the SwitchAlarm.Alarmed to false.	Yes	Supervisory, User
SwitchTime	Contains the date and time of the last switch between Active and Standby DI sources.	No	Read-Only
SwitchTimePrevious	Contains the date and time of the previous switch between Active and Standby DI sources.	No	Read-Only

Alarm Aggregation Attributes

The following attributes are available for all Objects. If alarm aggregation is enabled on the Area, the following attributes aggregate their respective alarm status values for the Area, for all sub-Areas, contained objects, and their descendants assigned to the Area. If alarm aggregation is disabled, these attributes remain at their default values. Alarm aggregation attributes behave similarly to alarm aggregation of individual attributes.

Attribute	Description	Run-Time Access (Supervisory, User, Read-Only, None)
<Attribute>.AlarmCntsBySeverity	Array of counts of all alarms that are in UNACK_ALM, ACK_ALM, or UNACK_RTN states on the object, aggregated by severity levels 1-4.	Read-Only
<Attribute>.AlarmMostUrgentAcked	TRUE (default) indicates that no alarms are in the InAlarm state or waiting to be Acked. A value of TRUE also indicates that the most urgent alarm(s) on the object and its descendants in the InAlarm state have been acknowledged, whether or not they are currently InAlarm.	Read-Only
<Attribute>.AlarmMostUrgentIn Alarm	FALSE (default) indicates that no alarms are in the InAlarm state or waiting to be Acked. A value of FALSE indicates whether the most urgent alarm(s) on the object and its descendants are in the InAlarm state, whether or not they have been acknowledged.	Read-Only
<Attribute>.AlarmMostUrgentMode	The AlarmMode of the most urgent alarm(s) on this Object and its descendants. If no alarms are in the InAlarm state or waiting to be Acked, the value is the same as the AlarmMode for the Object.	Read-Only
<Attribute>.AlarmMostUrgent Severity	Severity level expressed as an integer 1-4 of the most urgent alarm(s) on the object and its descendants. If no alarm is in the InAlarm state or waiting to be Acked, the value is 0 (zero).	Read-Only
<Attribute>.AlarmMostUrgent Shelved	The Shelved status as a Boolean value for the “most urgent” alarm(s) on this Object and its descendants. A value of FALSE indicates that no alarms have been Shelved for the "most urgent" alarm(s) on this Object and its descendants.	Read-Only