Automatic brake control
Description
Automatic brake control is activated if the controller is switched to the Operation enabled state of the CiA 402 Power State Machine; the brake otherwise always remains closed.
The brake output of the controller results in a PWM signal that can be adjusted with respect to frequency and duty cycle.
For information on the interaction of the brake with the motor stopping behavior, see also chapter Power State machine – halt motion reactions.
Activation and connection
The brake can be controlled either automatically or manually:
Connection
The brake output is located on X5 (see X5 – external holding brake)
Brake control
The following graphic shows the states of the CiA 402 Power State Machine together with the states of the brake for the automatic mode.
Brake PWM
The switched-on brake generates a PWM signal at the output of the controller that can be adjusted with respect to duty cycle and frequency. If an output pin without PWM is needed, a duty cycle of 100 percent can be set.
Frequency
The frequency of the brake PWM can be set in object 2038h:5h. The unit is Hertz; a value less than 50 or greater than 20000 is not possible.
Duty cycle
The duty cycle – the ratio of pulse to period duration – is set in 2038h:6h. The value is a percentage and can be selected between 2 and 100. With a value of 100, the output pin is permanently switched on.
In the following figure, example duty cycles of 25 and 50 percent are shown, whereby the frequency is held constant.