Driver for the microprocessor HW-584.
This project is coded to drive a 16 port network relay switch, HW-584. Click here to see the documentation of the switch. As a beginner tip, HW-584 is a network control switch with only ethernet port. Therefore, all the coding is done on server requests. Spesifically on GET requests.
Make sure that CURL library and ROS are installed. The project is developed with ROS Melodic. Project also may require you to reprogram the switch from this link. During the development phase, we observed that default program of the switch is neither stable enough nor sufficient.
You need to build the project at least once to control the network control switch. Create a workspace and put src folder in. Then, go to the workspace and type "catkin_make". That's all, you are ready to use the driver. Do not forget to start the roscore, simply type "roscore". Run the project with the command "rosrun". You can even send commands from terminal typing "rosservice call"! You can use the switch with both labels and relay IDs. Two services are defined and located under srv folder. They do the same job as labels are converted into IDs in the relayControlCallbackWlabel function. You can turn on and off the relays by simply changing the write_state. As stated in the service files, action 1 is READ whereas action 2 is WRITE. Note that if you would like to read the current status of a pin, the program would not care the write_state at all. In the read case, it must be either 1 or 0. Otherwise the program would return an error code. The program would returns success status and the relay status. If you WRITE a pin, the program returns the write_state you typed. In case of any type of error, the program returns a relay_state of -1. You can assing labels to the relay IDs at config/relay_map.yaml. You can also change the default URL and port provided by me from launch/relay_map_launch.launch. Note that as a default URL is 192.168.1.4 and port is 80. Example usage with relay ID : rosservice call /pdm_driver_node/relay_control_wid "relay_id: 4 action: 2 write_state: 1" Example usage with relay label : rosservice call /pdm_driver_node/relay_control_wlabel "relay_label: 'LIDAR_TOP' action: 1 write_state: 65" Note that since action 1 is READ, write_state won't matter for the program. 38
In the main function a PdmDriverNode class object is created. This class calls the related callback function according to the requested service. Both callback functions call the main callback function, relayControlCallback. In this function, a HW584_Curl class object is created. HW584_Curl implements an interface called HW584_Interface. This interface contains public functions such as init, send_read_request and send_write_request. Note that if you need to avoid using CURL library, you can reimplement HW584_Interface class. If you do so, you need to change the private member of the PdmDriver class, HW584_Curl hw584_curl_obj to your own object.
We could not observe too many bugs but a small issue. Time to time if switch cannot draw enough power to perform the command, it may restart itself. That may cause your program to stop responding. This is a physical problem more than a bug. Make sure that all the connections are perfect and the switch is receiving 5V supply. My idea to resolve the issue is to just simply add a timeout to the code. If the program cannot return a success or error in a certain time, it could return a timeout error.