Flashing a LED (command line)

ROS Terminal commands are a quick and easy way to see what’s going on with your RoNeX module. If you need to run something over and over again you’ll want to write a script or use the GUI, but for one off tests, or when you only have command line access, these commands can be very handy.

For the following commands you can use the tab key to auto complete the name of the topic/service and message type, and once you’ve entered the message type you can actually double tap tab again to produce an empty message in the correct format, handy for when you’re not familiar with the message types.

So if we’re interfacing with an LED we need to set the corresponding digital channel as an output, this can be done from the command line by calling the set_parameters service. In the example below we have also set the pwm_clock_divider parameter in the same message for convenience.

rosservice call /ronex/general_io/12/set_parameters "config:
  bools:
  - {name: 'input_mode_0', value: false}
  ints:
  - {name: 'pwm_clock_divider', value: 20}"

Once the channel is configured correctly we can publish a message to the command topic for the corresponding PWM module as shown below. Changing the pwm_on_time_0 value will adjust the brightness of the LED.

rostopic pub /ronex/general_io/12/command/pwm/0 sr_ronex_msgs/PWM "pwm_period: 64000
    pwm_on_time_0: 1000
    pwm_on_time_1: 0"