Pulse decoder

The Pulse decoder I/O decodes the two signals from a quadrature encoder to a pulse count/position. A quadrature encoder (or incremental rotary encoder or relative rotary encoder) has two outputs which are 90 degrees out of phase. That makes it possible to determine both position and direction of movement. The output of the Pulse decoder can be shown in a graph and in a table

Pulse decoder example

Properties and actions

To control the behavior of the Pulse decoder I/O, several properties are available. These can be accessed through a popup menu which is shown when the I/O is right clicked.

Voltage

The Voltage property sets the high and low level for signal edge detection. Several standard values are available that set both levels at once. A user defined setting is available to set both levels individually.

Step size

The Step size property indicates the physical size of one encoder step, in relation to the selected Unit. When the unit is set to e.g. meter, and there are 1000 encoder pulses per meter, Step size needs to be set to 0.001, which can also be entered as 1/1000 or as 1m (where m stands for milli).

Offset

The property Offset adds an starting offset in Unit to the determined encoder position.

Pulses per revolution

The property Pulses per revolution allows to set a number of pulses per revolution for the decoder. This setting limits the output of the encoder between zero and the selected number of pulses. When the encoder reaches a limit and then continues moving in the same direction, the output is reset to the other limit and starts counting again. This can be useful for applications where an encoder is connected to a rotating object.