Monitor the state of the robot

This article shows how to monitor a Staubli CS8 or CS9 controller from a PC, in C# or Python: which applications run, the state of each VAL 3 task, and the runtime errors. It gives a complete program that polls the controller and prints each change.

Prerequisites

• The SDK is connected to the controller: see Connect to your robot.
• Reading the state needs no right to change anything, and no VAL 3 program.

What to read

The SDK has no events for these values: poll them in a loop.

Example

using UnderAutomation.Staubli;
using UnderAutomation.Staubli.Soap.Data;

public class HowToMonitorState
{
    static void Main()
    {
        
        var controller = new StaubliController();
        controller.Connect("192.168.0.254");

        var lastStates = new Dictionary<string, ControllerTaskState>();

        // Poll the controller every 500 ms
        while (controller.Enabled)
        {
            // Applications that run
            string running = string.Join(", ", controller.Soap.GetValApplications()
                .Where(a => a.IsRunning)
                .Select(a => a.Name));

            foreach (ControllerTask task in controller.Soap.GetTasks())
            {
                // Report a change of state
                if (!lastStates.TryGetValue(task.Name, out var previous) || previous != task.State)
                    Console.WriteLine($"{DateTime.Now:T} {task.Name}: {previous} -> {task.State}");
                lastStates[task.Name] = task.State;

                // Report a runtime error of a VAL 3 task
                if (task.RuntimeError != 0)
                    Console.WriteLine($"{task.Name} error {task.RuntimeError}: {task.RuntimeErrorDescription}");
            }

            Thread.Sleep(500);
        }
        
    }
}

The program reads the applications and the tasks every 500 ms. It prints a line when the state of a task changes, and when a task has a runtime error. It runs while the connection is open.

Choose the polling period

Each method call is one request. A loop with two calls every 500 ms sends 4 requests per second. Measure the duration of a request on your cell, then choose a period that leaves the controller and the network free for the other clients, like Staubli Robotics Suite. For values that change fast, read them in one call: GetCurrentCartesianJointPosition gives the joints and the Cartesian position together, ReadIos reads several I/O together.

Troubleshooting

• WebException after a while: the network or the controller did not answer. Catch the exception, wait, and connect again.
• CustomSoapException with InvalidSessionIdCode: the session has expired, for example after a restart of the controller. Connect again.

What to read next

• VAL 3 tasks: the fields of a task.
• Run a VAL 3 program.
• Read and write I/O.