How to tune polling by code in a TANGO class

This HowTo explains how it is easily possible to tune attribute or command polling parameters in the code of a Tango class

Since Tango 8, it is possible to configure command or attribute polling within a Tango class code. A new set of polling related methods has been added to the base class Tango::DeviceImpl. These methods are similar to those you find in the Tango::DeviceProxy class when you write a Tango client. With them, you can

• Check if a command or attribute is polled
• Start/Stop polling for a command or a attribute
• Get or update polling period for a polled attribute or command

In C++

To display some information related to polling of the attribute named TheAtt:

string att_name("TheAtt");
cout << "Attribute " << att_name;

if (is_attribute_polled(att_name) == true)
   cout << " is polled with period " << get_attribute_poll_period(att_name) << " mS" << endl;
else
   cout << " is not polled" << endl;

To poll a command simply type:

poll_command("TheCmd",250);

 If the command is already polled, this method will update its polling period to 250 mS. Finally, to stop polling the same command, type:

stop_poll_command("TheCmd");

All these DeviceImpl polling related methods are documented in the DeviceImpl class documentation page

In Python

To display some information related to polling of the attribute named TheAtt, in a DeviceImpl context type:

att_name = "TheAtt"

if self.is_attribute_polled(att_name):
    print("{0} is polled with period {1} ms".format(att_name, self.get_attribute_poll_period(att_name))
else:
    print("{0} is not polled".format(att_name))

To poll a command, in a DeviceImpl context, simply type:

self.poll_command("TheCmd", 250)

 If the command is already polled, this method will update its polling period to 250 mS. Finally, to stop polling the same command, in a DeviceImpl context type:

self.stop_poll_command("TheCmd")

All these DeviceImpl polling related methods are documented in the PyTango DeviceImpl class documentation page.

In Java

The polling can be retrieved and modified from the DeviceManager class. Here is an example:

import org.tango.server.annotation.Device;
import org.tango.server.annotation.DeviceManagement;
import org.tango.server.device.DeviceManager;
import fr.esrf.Tango.DevFailed;
@Device
public class Test {
    @DeviceManagement
    private DeviceManager deviceManager;
     ...
        final String attName = "TheAttr";
        if (deviceManager.isPolled(attName)) {
            System.out.println(attName + " is polled with period " + deviceManager.getPollingPeriod(attName) + " mS");
        } else {
            System.out.println(attName + " is not polled");
        }
        deviceManager.startPolling("TheCmd", 250);
        deviceManager.stopPolling("TheCmd")
        ...
   
   public void setDeviceManager(final DeviceManager deviceManager) {
        this.deviceManager = deviceManager;
    }
}