Communicating with the robot controller

It is possible for a backend container contribution to communicate with the robots controller using different interfaces. To establish controller communication two parts are required:

In the Manifest.yaml describe what service the container should access.
From code implement the socket communication using the service name and correct interface port number.

Controller services

These are the available services that can be reached from a container contribution.

Service	DNS name	Description
Controller Primary	urcontrol-primary	Primary interface on controller
Controller Secondary	urcontrol-secondary	Secondary interface on controller
Controller Real-time	urcontrol-real-time	Real-time interface on controller
Controller RTDE	urcontrol-rtde	RTDE interface on controller
Controller interpreter	urcontrol-interpreter	Interpreter interface on controller
Controller primary read-only	urcontrol-primary-read-only	Read-only access
Controller secondary read-only	urcontrol-secondary-read-only	Read-only access
Controller real-time read-only	urcontrol-real-time-read-only	Read-only access
Container services	servicegateway	Ingress access to containers

Controller ports

These are the ports needed when creating a socket from code

Interface	Port
Primary	30001
Secondary	30002
Realtime (Deprecated)	30003
RTDE	30004
Primary read-only	30011
Secondary read-only	30012
Realtime read-only	30013
Interpreter	30020

Communicating with a service

The following is snippets from the calibration-info sample, that demonstrates how to set up a backend contribution for reading the controllers primary interface.

manifest.yaml

The following shows how the backend contribution of the calibration-info sample is configured to read from the controllers primary interface.

....
containers:
  - id: calibration-info
  image: calibration-info:latest
  services:
    - service: urcontrol-primary-read-only
...

The “services” section describe what services should be made available to the contribution (see “Controller services” table). “urcontrol-primary-read-only” will allow reading from the controller primary socket

Socket implementation

When implementing the socket communication the service name from the manifest must be used as host, the port can be found in the controller ports section above. In this case the host is “urcontrol-primary-read-only” and the port for the primary interface is 30001.

....
private static final String HOST = "urcontrol-primary-read-only";
private static final int PORT = 30011;
private final Socket socket;
private final DataInput input;

public ControllerConnection() throws IOException {
        socket = new Socket(HOST, PORT);
        input = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
}
...