Alarm Set Operation (ASO)

The Alarm Set Operation (ASO) instruction issues a specified operation to all alarm conditions of the specified alarm set. The Alarm Set Operation instruction is used to initiate asynchronous execution of an alarm operation for all alarm conditions of the specified alarm set. The instruction iterates through alarm conditions of the specified alarm set and sets an internal flag requesting the operation execution for each of the conditions. The internal flags have the same purpose and priority as the existing user accessible Progxxx bits and will be processed for all the alarm conditions of the specified alarm set during the next periodic evaluation of each particular alarm condition from the set.

Available Languages

Ladder Diagram

Function Block Diagram

This instruction is not available in Function Block Diagram.

Structured Text

ASO (Alarm Set, Alarm Set Control, Operation)Operands

The following table provides operands used for configuring the instruction.

Operand	Data Type	Format	Description
Alarm Set	ALARM_SET	AlarmSet	The ALARM_SET structure represents alarm conditions that are operated on by this instruction.
Alarm Set Control	ALARM_SET_CONTROL	tag	This data type contains three BOOL flags: EnableIn EnableOut LastState The instruction reacts to the edge (transition of .EnableIn from false to true) instead of the level. EnableOut is always set to .EnableIn. The request to perform the instruction operation have the same priority as ProgXXX flags.
Operation		immediate	This operand can be selected from the list or entered as an integer value: 0 - Acknowledge 1 - Reset 2 - Enable 3 - Disable 4- Unshelve 5 - Suppress 6 - Unsuppress 7 - ResetAlarmCount

Affects Math Status FlagsNoMajor/Minor FaultsNone specific to this instruction. See Index through arrays for array-indexing faults.Execution

Condition/State	Action Taken
Prescan	The instruction clears all ALARM_SET structure members.
Rung-condition -in is false	The instruction clears .EnableOut and .LastState structure members.
Rung-condition-in is true	If .LastState is false then the instruction initiates the operation and sets .LastState structure member to true. The .EnableOut structure member is always set to true.
Postscan	The instruction clears all ALARM_SET structure members.

OperationThe Alarm Set Operation instruction initiates asynchronous execution of one of the following alarm operations on the specified alarm set:

Acknowledge
Reset
Enable
Disable
Unshelve
Suppress
Unsuppress
ResetAlarmCount

The instruction iterates through all alarm conditions which are included in the specified alarm set or in the nested alarm sets to set an internal flag representing the request to perform the required operation on a particular alarm condition. The operation is initiated for all alarm conditions which are iterated by the instruction with the following exceptions:

Alarm Conditions which are configured not to support alarm operations
Alarm Conditions which are configured as not used

When an alarm operation is initiated for a particular alarm condition by the instruction, the operation is performed during the next alarm periodic evaluation of the alarm condition.When the instruction is called multiple times for the same Alarm Set to initiate contradictory alarm operations, the last requested operation is always applied to all alarm conditions in the Alarm Set. The alarm operations initiated for the Alarm Set may be applied to the conditions before the last requested operation is performed.When an Alarm Condition is periodically evaluated, the requests to perform particular alarm operations have the same priority as the requests to perform alarm operations initiated via user accessible Progxxx flags. It means that if a request to perform an alarm operation is generated by the instruction, then it is handled as if the corresponding Progxxx flag is set and the same rules used to resolve conflicting requests specified for ProgXXX flags are used to resolve conflicts between the instruction requests and requests made via Progxxx flags.The Alarm Set Operation instruction initiates the required alarm operation only when it detects the transition of .EnableIn value from false to true. In order to detect the transition, .LastState structure member is used to store .EnableIn value from the previous instruction execution. See the Execution section above.