Choke Step Method is used to adjust the opening size in a choke.

Method Signature:

Step(

[in] Direction ChokeCommandEnum,

[in] Steps UInt16,

[in] OverrideInterlocks Boolean,

[in] SEM SEMEnum

);

Table 23 – Choke Step Method Arguments

Argument	Description
Direction	Enumeration to indicate if an open request or close request is being initiated
Steps	The number of steps to either open or close the choke
OverrideInterlocks	Boolean indicating if the open or close command should override any defeatable interlocks
SEM	The selection of which SEM to send the command to.

Method result codes are defined as part of the Call Service (see OPC UA Services Part 4 – Services specification). They are described in Table 94 for ease of reference.

Comments

The choke Step Method initiates a move command. Parameters include the direction (open or close), the number of steps to step, overriding of any interlocks and the SEM selection to use for the command. After receiving the command, the choke will start to move. The Method will complete when the command has been accepted. The move operation may or may not have completed when the Method returns. The Method returns errors only if the operation cannot be started. The Client must monitor the Moving Variable to determine when the Step command actually finishes.

If a Server does not support an override of defeatable interlocks, then the OverrideInterlocks parameter will be ignored by the Server and if any interlocks are active the appropriate error code is returned.

If a Server does not support the selection of SEM, the SEM parameter is ignored.

Table 24 specifies the AddressSpace representation for the ChokeStepMethod.

Table 24 – Choke Step Method AddressSpace Definition

Attribute	Value
BrowseName	Step
References		Node Class	BrowseName	DataType	TypeDefinition	ModellingRule
HasProperty		Variable	InputArguments	Argument[]	PropertyType	Mandatory