[RQ7.1] The SAPI of the SafetyProvider represents the safety communication layer services of the SafetyProvider. Table 24lists all inputs and outputs of the SAPI of the SafetyProvider. Each SafetyProvider shall implement the SAPI as shown in Table 24, however, the details are vendor-specific.

Table 24– SAPI of the SafetyProvider

SAPI Term

Type

I/O

Definition

SafetyData

Structure

I

This input is used to accept the user data which is then transmitted as SafetyData in the SPDU.

NOTE: Whenever a new MNR is received from a SafetyConsumer, the state machine of the SafetyProvider will read a new value of the SafetyData from its corresponding Safety Application and use it until the next MNR is received.

NOTE: If no valid user data is available at the Safety Application, ActivateFSV is expected to be set to “1” by the Safety Application.

NonSafetyData

Structure

I

Used to consistently transmit non-safety data values (e.g. diagnostic information) together with safe data, see Clause 8.2.1.10

EnableTestMode

Boolean

I

By setting this input to “1” the remoteSafetyConsumer is informed (by Bit 2 in ResponseSPDU.Flags, see Clause 6.2.2) that the SafetyData are test data, and are not to be used for safety-related decisions. NOTE: The OPC UA Safety stack is intended for implementation in safety devices exclusively, see Clause 4.2.

OperatorAckProvider

Boolean

I

This input is used to implement an operator acknowledgment on the SafetyProvider side. The value will be forwarded to the SafetyConsumer, where it can be used to trigger a return from fail-safe substitute values (FSV) to actual process values (PV), see Annex B.2.4.

OperatorAckRequested

Boolean

O

Indicates that an operator acknowledge is requested by the SafetyConsumer. This flag is received within the RequestSPDU.

ActivateFSV(Fail-safeSubstituteValues)

Boolean

I

By setting this input to “1” the SafetyConsumer is instructed (via Bit 1 in ResponseSPDU.Flags, see Clause 6.2.2) to deliver FSV instead of PV to the safety application program.

NOTE: If the replacement of process values by FSV should be controllable in a more fine-grained way, this can be realized by using qualifiers within the SafetyData, see Clause 5.3.

SafetyConsumerID

UInt32

O

This output yields the ConsumerID used in the last access to this SafetyProvider by a SafetyConsumer (see Clause 6.1.3).

NOTE: all safety-related checks are executed by OPC UA Safety. The safety application is not required to check this SafetyConsumerID.

MonitoringNumber

UInt32

O

This output yields the monitoring number (MNR). It is updated whenever a new request comes in from the SafetyConsumer.

NOTE: all safety-related checks are executed by OPC UA Safety. The safety application is not required to check this Monitoring number.

SafetyProviderID

UInt32

I

For dynamic systems, this input can be set to a non-zero value. In this case, the SafetyProvider uses this value instead of the value from the SPI parameter SafetyProviderIDConfigured. If the value is changed to “0”, the value of parameter SafetyProviderIDConfigured from the SPI will be used (again).See Figure 11, Clause 3.2, and Clause 11.1.1.

For static systems, this input is usually always kept at value “0”.

SafetyBaseID

GUID

I

For dynamic systems, this input can be set to a non-zero value. In this case, the SafetyProvider uses this value instead of the value of the SPI parameter SafetyBaseIDConfigured. If the value is changed to “0”, the value of parameter SafetyBaseIDConfigured from the SPI will be used (again).See Figure 11, Clause 3.2, and Clause 11.1.1.

For static systems, this input is usually always kept at value “0”.