The SafetyProvider / SafetyConsumer tester "simulates" the behavior of an opposite SafetyProvider / SafetyConsumer Layer. Thus, it must be configured according to the deployed OPC UA communication system. This can be done with the help of an XML file associated with the tester.
A so-called “upper tester” runs on top of the SafetyProvider or SafetyConsumer within the device under test (DUT). It transfers data from the SafetyProvider or SafetyConsumer via its SAPI and makes them visible to the test tool via an OPC UA interface that is specified in the OPC UA Safety test specification (“Set Data” in Figure 26 and Figure 27). In a similar way, the upper tester enables the test-tool to set inputs of the SAPI (“Get Data” in Figure 26 and Figure 27).
The upper tester is implemented by the vendor of the DUT using standard program languages such as C/C++, IEC 61131-3 or Structured Text and does not need to be executed in a safety-related way.
Detailed requirements for the upper tester are described in the OPC UA Safety test specification.