Most Roboteq controllers outputs can drive a brake coil with maximum current consumption of 1 A and coil voltage up to 24V. The exact specs should be confirmed by referring to each controller’s datasheet.
Connecting a brake on a General-Purpose Output
The brake's coil can be connected directly to a controller’s output only if a flyback diode is connected in parallel with the coil and the coil's rated voltage is equal or lower than 24 V. The controller outputs are open drain, so one side of the coil must be connected to battery+ and the other side to the controller's output. The connection must be done according to image below:
The diode must be rated for 1A, forward bias voltage must be at least 100 V and reverse bias voltage must be more than 24 V.
In case the brake coil is rated for a higher voltage than 24V, then a relay must be connected to the controller's output to enable the brake. In that case, two different power sources should be used, one for the relay's coil and one for the brake's coil.
After the connections have been done, the controller's output can be configured on the Roborun+ utility to be activated when the motor is on. The respective channel that the brake will be used for must be ticked.
In case that the brake contact has a reverse logic, the output’s active level can be configured accordingly
With default configuration the brake will be controlled as follows:
- The brake will be disengaged when a motor command is given
- The brake will be engaged when the motor speed and power is zero
Minor differences in the default control of the brake might exist depending on the firmware version.
Connecting a brake on a dedicated brake output
There are controllers that have dedicated outputs for connecting a brake. One example is SBLM2360T controller. These outputs are controlled by a PWM signal so two different voltages can be applied on the brake. The one is the initial voltage required to release the brake (release voltage) and the other is the voltage that is required to hold the brake (hold voltage). That way the overall power consumption of the brake is lower. Between the two applied voltages there is a configurable delay time.
The control logic of the brake is similar to the previous implementation, with the difference that this time two different voltages will be applied while the brake is disengaged. This time the connection to battery+ is implemented internally on the controller. so the user will only have to connect the brake coil between the Brk+ and Brk -. The user should check on each controller’s datasheet to confirm if a reverse diode exists on the controller or it should be added externally.
Please note that most controllers use shared pins for brakes and digital outputs so the output function should be configured on the Utility. Please check on the controller's datasheet which are the common output used, to enable them.
Custom brake implementation
The brake operation can be very different on each application. For example, the default implementation where the brakes will be engaged only when the speed of the motor is zero, will not be suitable for a winch application, where the load will continue to fall due to its weight even if a zero-motor command is given. Such problems can be solved by configuring the controller’s output to be never triggered and writing a Microbasic script to control the output according to the application needs.
