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- Enable: Checking this box enables the generation of encoder data for the channels in the group once the simulation has started, provided that the type of functionality is set to Encoder Out (see item below for more detail). Clicking Enable also adds the connection points for each encoder's (up to 2 per group) angular rate (or speed) in the Configuration panel of RT-LAB. In order to output data, connections must be made between points in the model (in the form of OpOutput blocks) and the encoder output connectable points. Connections with Dashboards panels are also possible. To create a connection , the user drags and drops the connectable items onto an to the appropriate OpOutput block in the Configuration panel of the RT-LAB project, use the Dashboards interface, accessible from the project, and refer to its documentation.
Digital type: Given that the encoder functionality cannot be selected dynamically (i.e. it is not part of the SDIO functionality), this field is always grayed out. For the sending of angular rate values, verify that the field displays Encoder Out.
Number of encoder signals: The value entered in this field represents how many encoders of the group are to be controlled. There are at most two encoders per group, therefore the user has the option of controlling just one encoder or both. An encoder is composed of a set of A, B and Z signals. Frequency values will be transmitted from the model to the FPGA at each calculation step for each encoder. This value is then used to compute the state of the A, B and Z signals. These signals are output on the physical module's channels as such:
Index in group Usage first channel of the group channel A of the first encoder second channel of the group channel B of the first encoder third channel of the group channel Z of the first encoder fourth channel of the group channel A of the second encoder fifth channel of the group channel B of the second encoder sixth channel of the group channel Z of the second encoder seventh channel of the group not used eighth channel of the group not used Regardless of how many encoders are used, the last two channels of the group always output '0'. They are not controlled by any kind of functionality (such as PWM, static or time-stamped digital). When only one encoder is used, the second encoder's outputs are disabled. Therefore, the fourth up to the last channels of the group outputs '0'.
Frequency unit: The unit in which the angular rate provided in the model is to be interpreted. The user has the choice between revolutions-per-minute (RPM) or Hertz (Hz).
Resolution (# of cycles per revolution): The resolution is also known as pulses-per-revolution (PPR) or count per revolution (CPR). The value entered in this field represents the number of cycles of the A and B signals per revolution. Its maximum is 32767 cycles per revolution. However, the maximum resolution combined with high rates leads to precision loss. The highest resolution at which the maximum speed of 10000 RPM (166.67 Hz) or negative values are achievable is 25000 PPR.
Clockwise rotation: This parameter determines whether the encoder signals are produced with signal A leading signal B (causing a clockwise rotation), or the reverse.
Polarity: This parameter allows the user to choose the polarity of the A, B and Z signals of the encoder(s). Is it presented as a drop-down list and the two choices the list offers are Active high (default) and Active low. Active high or Active low mean that the active part of the duty cycle is either low (low voltage) or high (high voltage). A signal configured to be Active high outputs a high voltage value for the active part of its duty cycle, whereas an Active low signal outputs a low voltage value for the active part of its duty cycle.
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