OPC Alarm and Event Data

OPC alarm event categories are made available to subscribing alarm clients (in AlarmWorX64 Viewer, GraphWorX64 displays, and other runtime access tools). The information provided in this topic is helpful when working with Alarm Categories.

Below in this topic are:

Events and Their Attributes

This table shows the different event types, their names, and their attributes.

Alarm Event Attributes

Event Name	Deviation	Digital	Limit	Rate of Change	Type	Comment
ACK COMMENT					VT_BSTR	Comment entered when alarm was last acknowledged.
ALARM COUNT					VT_I4	Number of alarm transitions before acknowledge.
AREA					VT_ARRAY \| VT_BSTR	Array of areas.
CV					VT_R8	Current Value (OPC Input 1 or 2).
DEADBAND					VT_BOOL	Alarm detection Deadband.
DEFAULT DISPLAY					VT_R8	A text string, usually a file name, that when launched provides related information.
HELP TEXT					VT_BSTR	Help information.
LIMIT VALUE EXCEEDED					VT_BSTR	The Current Value at the time the limit was exceeded.
LOOP DESC					VT_R8	A description of the Source (tag).
NEXT_LIM					VT_BSTR	The value of the next limit.
NORMAL STATE					VT_R8	Value of the normal state (TRUE or FALSE).
PREV LIM					VT_BOOL	Value of the previous limit reached.
RELATED VALUE 01-10					VT_R8	Associates up to 10 OPC tags or expressions with each alarm tag as ”r;supplemental” information to the alarm.
SP					VT_SP	Setpoint (OPC Input 2)

OPC Data Access Interface

The AlarmWorX64 Server exposes much of its real-time and configuration data via the OPC Data Access specification. This allows OPC Data Access client applications, such as GraphWorX64, to make use of alarm-related data without using the OPC Alarm & Events interface. Some typical uses would include:

Changing the color of a graphic symbol to correspond to alarm state.
Displaying alarm limits.
Allowing alarm limits to be changed by the operator.

The following table lists the OPC item names that are available from the server.

OPC Data Access Items

Item Name	Type	Read/Write	Comment
Active	VT_BOOL	R	Tag's Global Alarm Active Bit.
Name	VT_BSTR	R	Tag Name (Source).
Input1	VT_BSTR	R
BaseText	VT_BSTR	R
Enabled	VT_BOOL	R	Enabled state of the Source (tag).
HelpText	VT_BSTR	R
LIM_RTNText	VT_BSTR	R
LIM_Input2	VT_R8	R
LIM_Deadband	VT_R8	R
LIM_Active	VT_BOOL	R
LIM_Acked	VT_BOOL	R/W
LIM_HIHI_Active	VT_BOOL	R
LIM_HIHI_Enabled	VT_BOOL	R/W
LIM_HIHI_RequiresAck	VT_BOOL	R/W
LIM_HIHI_Severity	VT_R8	R/W
LIM_HIHI_Limit	VT_R8	R/W
LIM_HIHI_MsgText	VT_BSTR	R/W
LIM_HI_Active	VT_BOOL	R
LIM_HI_Enabled	VT_BOOL	R/W
LIM_HI_RequiresAck	VT_BOOL	R/W
LIM_HI_Severity	VT_R8	R/W
LIM_HI_Limit	VT_R8	R/W
LIM_HI_MsgText	VT_BSTR	R/W
LIM_LOLO_Active	VT_BOOL	R
LIM_LOLO_Enabled	VT_BOOL	R/W
LIM_LOLO_RequiresAck	VT_BOOL	R/W
LIM_LOLO_Severity	VT_R8	R/W
LIM_LOLO_Limit	VT_R8	R/W
LIM_LOLO_MsgText	VT_BSTR	R/W
LIM_LO_Active	VT_BOOL	R
LIM_LO_Enabled	VT_BOOL	R/W
LIM_LO_RequiresAck	VT_BOOL	R/W
LIM_LO_Severity	VT_R8	R/W
LIM_LO_Limit	VT_R8	R/W
LIM_LO_MsgText	VT_BSTR	R/W
DEV_RTNText	VT_BSTR	R
DEV_Input2	VT_R8	R
DEV_Deadband	VT_R8	R
DEV_Active	VT_BOOL	R
DEV_Acked	VT_BOOL	R/W
DEV_HIHI_Enabled	VT_BOOL	R/W
DEV_HIHI_RequiresAck	VT_BOOL	R/W
DEV_HIHI_Severity	VT_R8	R/W
DEV_HIHI_Limit	VT_R8	R/W
DEV_HIHI_MsgText	VT_BSTR	R/W
DEV_HI_Enabled	VT_BOOL	R/W
DEV_HI_RequiresAck	VT_BOOL	R/W
DEV_HI_Severity	VT_R8	R/W
DEV_HI_Limit	VT_R8	R/W
DEV_HI_MsgText	VT_BSTR	R/W
DEV_LOLO_Enabled	VT_BOOL	R/W
DEV_LOLO_RequiresAck	VT_BOOL	R/W
DEV_LOLO_Severity	VT_R8	R/W
DEV_LOLO_Limit	VT_R8	R/W
DEV_LOLO_MsgText	VT_BSTR	R/W
DEV_LO_Enabled	VT_BOOL	R/W
DEV_LO_RequiresAck	VT_BOOL	R/W
DEV_LO_Severity	VT_R8 R/W	R/W
DEV_LO_Limit	VT_R8 R/W	R/W
DEV_LO_MsgText	VT_BSTR	R/W
DIG_RTNText	VT_R8 R/W	R
DIG_Input2	VT_R8	R
DIG_Active	VT_BOOL	R
DIG_Acked	VT_BOOL	R/W
DIG_Enabled	VT_BOOL	R/W
DIG_RequiresAck	VT_BOOL	R/W
DIG_Severity	VT_R8	R/W
DIG_Limit	VT_R8	R/W
DIG_MsgText	VT_BSTR	R/W
ROC_RTNText	VT_BSTR	R
ROC_Input2	VT_R8	R
ROC_Active	VT_BOOL	R
ROC_Acked	VT_BOOL	R/W
ROC_Enabled	VT_BOOL	R/W
ROC_RequiresAck	VT_BOOL	R/W
ROC_Severity	VT_R8	R/W
ROC_Limit	VT_R8	R/W
ROC_MsgText	VT_BSTR	R/W
LIM_HIHI_Active	VT_BOOL	R
LIM_HI_Active	VT_BOOL	R
LIM_LOLO_Active	VT_BOOL	R
LIM_LO_Active	VT_BOOL	R
DEV_HIHI_Active	VT_BOOL
DEV_HI_Active	VT_BOOL
DEV_LOLO_Active	VT_BOOL
DEV_LO_Active	VT_BOOL

Area Bits

Item Name	Type	Read/Write	Comment
Area_Active	VT_BOOL	R	Notifies that one or more tags in the current area is in active state.
Area_Unacked	VT_BOOL	R	Notifies that one or more tags in the current area has not been acknowledged.
Recursive_Active	VT_BOOL	R	Notifies that one or more tags in the current area or any subdirectories is in active state.
Recursive_Unacked	VT_BOOL	R	Notifies that one or more tags in the current area or any subdirectories has not been acknowledged.

Error Reporting

Internal errors encountered by the AlarmWorX64 Server are reported via the GENESIS64 Event Server, another OPC Alarm & Events compliant server. The GENESIS64 Event Server can optionally write selected events to the NT Event Log. The following simple events may be generated by the AlarmWorX64 Server : For the GENESIS64 Event Server, severity values of 600 and below are considered "normal," and severity values of 601 to 1000 are considered errors.

Server Errors

Severity	Message
500	"%1 %2 Started."
500	"%1 %2 Stopped."
700	"Alarm Tag: %1, Condition: %2, Input Item: %3, Error: Unknown"
700	"Alarm Tag: %1, Condition: %2, Input Item: %3, Error: Tag does not exist."
700	"Alarm Tag: %1, Condition: %2, Input Item: %3, Error: Rejected by Security Server ."
700	"Alarm Tag: %1, Condition: %2, Input Item: %3, Error: Licensed I/O Point Count Exceeded. "
700	"Alarm Tag: %1, Condition: %2, Input Item: %3, Error: Demo mode has timed out."
700	"Alarm Tag: %1, Condition: %2, Input Item: %3, Error: Local I/O not allowed on Browser node."
700	"Alarm Tag: %1, Condition: %2, Input Item: %3, Error: COM error registering with GenRegistrar."
800	"%1 %2 Failed to Register with GenRegistrar. Reason: %3"
800	"No configuration found for node and no ""Default"" configuration in Database Provider: %1 Connection: %2"
800	"Database Error - Provider: %1 Connection: %2"