How to tune polling by code in a TANGO class
Intended audience: advanced developers,
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++
Programming language: c++
To display some information related to polling of the attribute named TheAtt:
1string att_name("TheAtt");
2cout << "Attribute " << att_name;
3
4if (is_attribute_polled(att_name) == true)
5 cout << " is polled with period " << get_attribute_poll_period(att_name) << " mS" << endl;
6else
7 cout << " is not polled" << endl;
To poll a command simply type:
1poll_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:
1stop_poll_command("TheCmd");
All these DeviceImpl polling related methods are documented in the DeviceImpl class documentation page
In Python
Programming language: python
To display some information related to polling of the attribute named TheAtt, in a DeviceImpl context type:
1att_name = "TheAtt"
2
3if self.is_attribute_polled(att_name):
4 print("{0} is polled with period {1} ms".format(att_name, self.get_attribute_poll_period(att_name))
5else:
6 print("{0} is not polled".format(att_name))
To poll a command, in a DeviceImpl context, simply type:
1self.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:
1self.stop_poll_command("TheCmd")
All these DeviceImpl polling related methods are documented in the PyTango DeviceImpl class documentation page.
In Java
Programming language: java
The polling can be retrieved and modified from the DeviceManager class. Here is an example:
1import org.tango.server.annotation.Device;
2import org.tango.server.annotation.DeviceManagement;
3import org.tango.server.device.DeviceManager;
4import fr.esrf.Tango.DevFailed;
5@Device
6public class Test {
7 @DeviceManagement
8 private DeviceManager deviceManager;
9 ...
10 final String attName = "TheAttr";
11 if (deviceManager.isPolled(attName)) {
12 System.out.println(attName + " is polled with period " + deviceManager.getPollingPeriod(attName) + " mS");
13 } else {
14 System.out.println(attName + " is not polled");
15 }
16 deviceManager.startPolling("TheCmd", 250);
17 deviceManager.stopPolling("TheCmd")
18 ...
19
20 public void setDeviceManager(final DeviceManager deviceManager) {
21 this.deviceManager = deviceManager;
22 }
23}