[MagiChau]

getPeriod() would be working as intended. If the encoder is not getting a pulse it means the velocity is zero and thus getPeriod is zero.

Here's the actual source code for the method.

public double getPeriod() {
        double period;
        if (m_counter.readTimerOutput_Stalled()) {
            return Double.POSITIVE_INFINITY;
        } else {
            period = (double) m_counter.readTimerOutput_Period() / (double) m_counter.readTimerOutput_Count();
        }
        return period / 1.0e6;
    }

The counter class will run the getStopped() method if the pulse did not change within x period and set the time to stalled.

public boolean getStopped() {
        return m_counter.readTimerOutput_Stalled();
    }