Automatic brake control
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:
The following graphic shows the states of the CiA 402 Power State Machine together with the states of the brake for the automatic mode.
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.
The Brake + pin of the brake output is connected to the voltage supply of the controller.
If the operating voltage of the brake is greater than the supply voltage of the controller, you cannot use the brake output of the controller; you must supply the brake externally.
If the supply voltage of the controller is greater than the operating voltage of the brake (and up to 48 V DC), it is recommended that the PWM controller from Nanotec with order designation EB-BRAKE-48V be used and the duty cycle of the controller brake output be set to "100".
The frequency of the brake PWM can be set in object 2038h:5h. The unit is Hertz; a value greater than 2000 is not possible.
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.