Differences

This shows you the differences between two versions of the page.

--- eeros_architecture:safety_system:start [2016/11/03 17:27] – [Events] graf
+++ eeros_architecture:safety_system:start [2023/02/26 17:59] (current) – [How it works] ursgraf
@@ Line 8: / Line 8: @@
      - has a unique name
      - defines the state of all critical outputs
-     - defines conditions of the critical inputs, which are proofed periodically by an inspection task
+     - defines conditions for the critical inputs, which are checked periodically by an inspection task
-     - can have accept certain events
+     - can accept certain events
      - can cause events
   * The order of the safety level numbering corresponds to the potential damage in case of an error
@@ Line 20: / Line 20: @@
 Events are exclusively received and handled by the safety system. An event can cause a change of the safety level. Such a change can happen only if this specific event was registered for the current level. The next figure shows a couple of safety levels together with associated events causing a level change.
 {{ .:safetysystemevents1.png?300 | //Typical safety levels and associated events//}}
+  * If the safety system itself causes an event leading to a change of the safety level, this level change takes place only after the safety system completes this run.
+  * Multiple events fired during a single safety period would lead to ambiguities. The event leading to a lower prioritized safety level wins, while the other events are cancelled.
+===== What does the Safety System do ? =====
+The most important function of the safety system is its run method. This method is called periodically by the executor. Here's how it works:
+<code cpp>
+  void SafetySystem::run() {
+    // 1) Read inputs and check them
+    for(auto ia : level->inputAction) {
+      if(ia != nullptr) ia->check(&privateContext);
+    }
+    // 2) Execute level action
+    if(level->action != nullptr) level->action(&privateContext);
+    // 3) Set outputs
+    for(auto oa : level->outputAction) {
+      if(oa != nullptr) oa->set();
+    }
+  }
+</code>
 If you want to learn more about the individual parts of the safety system, look at the links below:
-  *[[.:hal|HAL (Hardware Abstraction Layer)]]\\
-  *[[.:properties|Safety Properties]] \\
+  *[[.:properties|Safety Properties]]
-  *[[.:io_actions|Input / Output Actions]]\\
+  *[[.:io_actions|Input / Output Actions]]
-  *[[.:usage|Creation]]
+  *[[.:usage|Setup a Safety System]]