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--- eeros_architecture:control_system:signals [2017/03/17 12:06] – [Properties] graf
+++ eeros_architecture:control_system:signals [2021/03/03 08:29] (current) – [Reading from Unconnected Inputs] ursgraf
@@ Line 6: / Line 6: @@
 Each element of a signal is characterized by a value, a high precision timestamp, a name and additional properties, depending on the type of signal, which will provide semantic information. Some examples are dimension (e.g. length, mass, current, etc.), SI-unit (e.g. m, m/s, kg, Nm, A, etc.), reference coordinate system or activation state (enabled/disabled). Other properties could include information about the quality of the signal like noise or quantification which could be used for Kalman filtering.
-{{ signaluml.png?150 | Signal type with its properties}}
+[{{ signaluml.png?150 | //Signal type with its properties//}}]
 It's important to note that a signal can carry a single value as well as a vector or matrix of values. For this purpose the field //value// is declared as of type T.
@@ Line 25: / Line 25: @@
 </code>
 This is shown in the following diagram:
-{{ sumblock.png?300 | //Summation block with threedimensional signals//}}
+[{{ sumblock.png?300 | //Summation block with threedimensional signals//}}]
-The functions //getIn()// and //getOut()// return an input or output signal, respectively. With the summation block, //getOut()// returns the single output signal.
+The functions //getIn()// and //getOut()// return an input or output. To access the signals on those in- or outputs, use //getSignal()//.
-===== Using Signals =====
+===== Timestamp =====
-The example below shows a gain block being defined, where its input and output are set to a two dimensional vector. Its gain is therefore a 2x2-matrix.
+Every signal carries a timestamp. The timestamp of a signal is usually set in input blocks. Block which read from an external source and deliver this value on a output signal will set its timestamp to the time of the acquisition of the value. \\
-<code cpp>
+Most blocks will not alter this timestamp. However, blocks which depend on the sampling time such as integrators or differentiators will change the timestamp according to their inner algorithm.
-  Gain<Vector2, Matrix<2,2>> g1({1,2.5,-1,-0.5});
-</code>
+===== Reading from Unconnected Inputs =====
+If you try to read from an input, which is not connected to an output, a //NotConnectedFault// is thrown. Please make sure that such faults are handled correctly. For an example refer to [[getting_started:tutorials:controlsystem|]].
-If a ''Gain'' block is declared with a simple value, a eye matrix with this value is created internally.
-<code cpp>
-  Gain<Vector2> g2(10);
-</code>
-In order to access the individual dimensions of a certain signal, use functions like
-<code cpp>
-  g1.getOut().getValue();  // returns value of gain output
-  g1.getOut().getValue().getRow(1);  // returns row 1 of gain output
-</code>