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--- getting_started:tutorials:stoppingsystem [2016/11/07 09:07] – graf
+++ getting_started:tutorials:stoppingsystem [2017/09/24 16:39] (current) – removed graf
@@ Line 1: / Line 1: @@
-====== Shutting down a System ======
-How does a robot control system properly shut down? In general it does never stop. Pressing an emergency button might switch to a emergency safety level. However, in a system under development it is often desirable to end an application. That usually means to switch to a specific safety level where the necessary steps for a well controlled stopping of the application takes place. Only after this happened the executor stops running and returns control to the main program, which then stops as well. \\
-The following example shows how this can be accomplished. The code can be found in [[getting_started:tutorials:safetysystem|]]. First of all you have to define a signal handler which handles all kind of signals, among them the ''SIGINT'' signal which is sent by pressing ''Ctrl-C''.
-<code cpp>
-#include "MySafetyProperties.hpp>
-#include <signal.h>
-void signalHandler(int signum) {
-	SafetySystem::exitHandler();
-}
-int main() {
-  signal(SIGHUP, signalHandler);
-  signal(SIGINT, signalHandler);
-  signal(SIGQUIT, signalHandler);
-  signal(SIGKILL, signalHandler);
-  signal(SIGTERM, signalHandler);
-  signal(SIGPWR, signalHandler);
-  ...
-  // Create and initialize safety system
-  double period = 1;
-  MySafetyProperties ssProperties;
-  SafetySystem safetySys(ssProperties, period);
-  ...
-}
-</code>
-The ''exitHandler'' in the safety system runs a predefined exit function which must be defined in your safety properties.
-<code cpp>
-exitFunction = [&](SafetyContext* privateContext) {
-  privateContext->triggerEvent(seShutDown);
-};
-</code>
-In the example this function triggers a safety event ''seShutDown''. You have to add this event to all safety levels where you actually want to allow shutting down the machine.
-After pressing ''Ctrl-C'' the safety system will go into the safety level ''slShuttingDown'', see example in [[getting_started:tutorials:safetysystem|]].
-The system will stay in the level as long as the shutting down will take. This could include a whole sequence of steps such as applying brakes or driving to a safe position. As soon as this point is reached another safety event, ''seSwitchingOff'' is triggered which leads to a safety level change to ''slOff''. The action to be taken in this level is stopping the executor. Therefore, you have to assign a level action in your safety properties as follows:
-<code cpp>
-slOff.setLevelAction([&](SafetyContext* privateContext) {Executor::stop();});
-</code>
-This will cause the executor to stop running and return control to the main programm which in turns will exit.