7 Safety communication layer services and management ToC Previous Next

7.4 SafetyConsumer interfaces ToC Previous Next

The Figure 12 shows an overview of the SafetyConsumer interfaces. The SAPI is specified in Clause 7.4.1, the SPI is specified in Clause 7.4.3.

readme_files/image014.png Figure 12 – SafetyConsumer interfaces

7.4.1 SAPI of SafetyConsumer ToC Previous Next

The SAPI of the SafetyConsumer represents the Safety communication layer services of the SafetyConsumer. Table 16 lists all inputs and outputs of the SAPI of the SafetyConsumer. [RQ7.4] Each SafetyConsumer shall implement the SAPI as shown in Table 16, however, the details are vendor specific.

Table 16 – SAPI of the SafetyConsumer

SAPI Term Type Definition
SafetyData Structure This output either delivers the process values received from the SafetyProvider in the SPDU field SafetyData, or FSV.
NonSafetyData Structure Used to consistently transmit non-safety data values (e.g. diagnostic information) together with safe data, see Clause 8.1.1.10
Enable Boolean By changing this input to “0” the SafetyConsumer will change each and every variable of the SafetyData to “0” and stop sending requests to the SafetyProvider. When changing Enable to “1” the SafetyConsumer will restart safe communication. The variable can be used to delay the start of the OPC UA Safety communication, after power on until “OPC UA connection ready” is set. The delay time is not monitored while enable is set to “0”.
FSV_Activated Boolean This output indicates via “1”, that on the output SafetyData FSV (all binary “0”) are provided.
NOTE: If an application needs different FSV than “all binary 0”, it is expected to use appropriate constants and ignore the output of SafetyData whenever FSV_Activated is set.

NOTE: If the ResponseSPDU is checked with error: ActivateFSV is set.
OperatorAckConsumer
Boolean For motivation, see Clause 7.4.2.
After an indication of OperatorAckRequested this input can be used to signal an operator acknowledgment. By changing this input from “0” to “1” (rising edge) the SafetyConsumer is instructed to switch SafetyData from FSV to PV. OperatorAckConsumer is processed only if this rising edge arrives after OperatorAckRequested was set to “1”, see Figure 18.
If a rising edge of OperatorAckConsumer arrives before OperatorAckRequested becomes 1, this rising edge is ignored.
OperatorAckRequested Boolean This output indicates the request for operator acknowledgment. The bit is set to “1” by the SafetyConsumer, when three conditions are met:
1. Too many communication errors were detected in the past, so the SafetyConsumer decided to switch to fail-safe substitute values.
2. Currently, no communication errors occur, and hence operator acknowledgment is possible.
3. Operator acknowledgment (rising edge at input OperatorAckConsumer) has not yet occurred.
The bit is reset to “0” when a rising edge at OperatorAckConsumer is detected.
OperatorAckProvider Boolean This output indicates that an operator acknowledgment has taken place on the SafetyProvider. If operator acknowledgment at the SafetyProvider should be allowed, this output is connected to OperatorAckConsumer, see Annex B.2.4 and B.2.5.
NOTE: If the ResponseSPDU is checked with error, this output remains last value.
TestModeActivated Boolean The safety application program is expected to evaluate this output for determining whether the communication partner is in test mode or not. A value of “1” indicates that the communication partner (source of data) is in test mode, e.g. during commissioning. Data coming from a device in test mode may be used for testing but is not intended to be used to control safety-critical processes. A value of “0” represents the “normal” safety-related mode.
Motivation: Test mode enables the programmer and commissioner to validate the safety application using test data. NOTE: If the ResponseSPDU is checked with error: TestModeActivated is reset.
SafetyProviderID UInt32 By changing this input to a non-zero value, the SafetyConsumer uses this variable instead of the SPI-Parameter SafetyProviderID. This input is only read in the first cycle, or when a rising edge occurs at the input Enable. See also Table 17. If it is changed to “0”, the parameter SafetyProviderID will become activated.
SafetyBaseID GUID By changing this input to a non-zero-value the SafetyConsumer uses this variable instead of the SPI-Parameter SafetyBaseID. This input is only read in the first cycle, or when a rising edge occurs at the input Enable. See also Table 17. If it is changed to “0”, the SPI-parameter SafetyBaseID will become activated.
SafetyConsumerID UInt32 By changing this input to a non-zero-value the SafetyConsumer uses this variable instead of the SPI-Parameter SafetyConsumerID. This input is only read in the first cycle, or when a rising edge occurs at the input Enable. See also Table 17. If it is changed to “0”, the SPI-parameter SafetyConsumerID will become activated.

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