Figure 11 shows the structure of a RequestSPDU which originates at the SafetyConsumer and contains a SafetyConsumerID, a MonitoringNumber (MNR), and one octet of (non-safety-related) Flags. See 7.2.1.2 to 7.2.1.4 for details. See 6.2.3.3 for details on the RequestSPDUDataType definition.

NOTE 1 The RequestSPDU does not contain a CRC signature.

Figure 11 – RequestSPDU

Figure 12 shows the structure of a ResponseSPDU which originates at the SafetyProvider and contains the SafetyData (1 to 1 500 octets), an additional 25 octet safety code (STrailer) and the NonSafetyData. See 7.2.1.5 to 7.2.1.11 for details. See 6.2.3.4 for details on the ResponseSPDUDataType definition.

Figure 12 – ResponseSPDU

NOTE 2 To avoid spurious trips, the ResponseSPDU is transmitted in an atomic (consistent) way from the OPC UA Platform Interface of the SafetyProvider to the OPC UA Platform Interface of the SafetyConsumer. This is the task of the respective OPC UA mapper, see Figure 2.