High level server API
Server helper classes for writing Tango device servers.
This module provides a high level device server API. It implements TEP1. It exposes an easier API for developing a Tango device server.
Here is a simple example on how to write a Clock device server using the high level API:
import time
from tango.server import run
from tango.server import Device
from tango.server import attribute, command
class Clock(Device):
time = attribute()
def read_time(self):
return time.time()
@command(dtype_in=str, dtype_out=str)
def strftime(self, format):
return time.strftime(format)
if __name__ == "__main__":
run((Clock,))
Here is a more complete example on how to write a PowerSupply device server using the high level API. The example contains:
device description (via docstring), which user can get later as DeviceProxy.description()
default state DevState.ON and default status “Device is current supply mode”
a read-only double scalar attribute called voltage
a read/write double scalar expert attribute current
a read-only double image attribute called noise
a ramp command
a host device property
a port class property
1from time import time
2from numpy.random import random_sample
3
4from tango import AttrQuality, AttrWriteType, DispLevel
5from tango.server import Device, attribute, command
6from tango.server import class_property, device_property
7
8class PowerSupply(Device):
9 """PyTango example of PowerSuppy device."""
10
11 # alternative way to add device description (see note below)
12 DEVICE_CLASS_DESCRIPTION = "PyTango example of PowerSuppy device."
13
14 DEVICE_CLASS_INITIAL_STATUS = "Device is in current supply mode"
15 DEVICE_CLASS_INITIAL_STATE = DevState.ON
16
17 voltage = attribute()
18
19 current = attribute(label="Current", dtype=float,
20 display_level=DispLevel.EXPERT,
21 access=AttrWriteType.READ_WRITE,
22 unit="A", format="8.4f",
23 min_value=0.0, max_value=8.5,
24 min_alarm=0.1, max_alarm=8.4,
25 min_warning=0.5, max_warning=8.0,
26 fget="get_current", fset="set_current",
27 doc="the power supply current")
28
29 noise = attribute(label="Noise", dtype=((float,),),
30 max_dim_x=1024, max_dim_y=1024,
31 fget="get_noise")
32
33 host = device_property(dtype=str)
34 port = class_property(dtype=int, default_value=9788)
35
36 def read_voltage(self):
37 self.info_stream("get voltage(%s, %d)" % (self.host, self.port))
38 return 10.0
39
40 def get_current(self):
41 return 2.3456, time(), AttrQuality.ATTR_WARNING
42
43 def set_current(self, current):
44 print("Current set to %f" % current)
45
46 def get_noise(self):
47 return random_sample((1024, 1024))
48
49 @command(dtype_in=float)
50 def ramp(self, value):
51 print("Ramping up...")
52
53if __name__ == "__main__":
54 PowerSupply.run_server()
Pretty cool, uh?
Note
the device description can be added either by class docstring or by DEVICE_CLASS_DESCRIPTION class member, the latter has priority over the docstring. The important difference is that DEVICE_CLASS_DESCRIPTION will be inherited by child classes, while the docstring will not be.
Data types
When declaring attributes, properties or commands, one of the most important
information is the data type. It is given by the keyword argument dtype.
In order to provide a more pythonic interface, this argument is not restricted
to the CmdArgType
options.
For example, to define a SCALAR DevLong
attribute you have several possibilities:
‘int’
‘int64’
tango.CmdArgType.DevLong64
‘DevLong64’
To define a SPECTRUM attribute simply wrap the scalar data type in any python sequence:
using a tuple:
(:obj:`int`,)
orusing a list:
[:obj:`int`]
orany other sequence type
To define an IMAGE attribute simply wrap the scalar data type in any python sequence of sequences:
using a tuple:
((:obj:`int`,),)
orusing a list:
[[:obj:`int`]]
orany other sequence type
Below is the complete table of equivalences.
dtype argument |
converts to tango type |
---|---|
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- class tango.server.Device(cl, name)
Bases:
BaseDevice
Device class for the high-level API.
All device-specific classes should inherit from this class.
- DEVICE_CLASS_DESCRIPTION: ClassVar[str | None]
Description of the device class (optional).
If not specified, the class docstring is used. Available to clients via
tango.DeviceProxy.description()
. Use as a class variable.
- DEVICE_CLASS_INITIAL_STATE: ClassVar[DevState]
Initial state value for all instances of the device (optional).
Use as a class variable.
- DEVICE_CLASS_INITIAL_STATUS: ClassVar[str]
Initial status string for all instances of the device (optional).
Use as a class variable.
- add_attribute(self, attr, r_meth=None, w_meth=None, is_allo_meth=None) Attr
Add a new attribute to the device attribute list.
Please, note that if you add an attribute to a device at device creation time, this attribute will be added to the device class attribute list. Therefore, all devices belonging to the same class created after this attribute addition will also have this attribute.
If you pass a reference to unbound method for read, write or is_allowed method (e.g. DeviceClass.read_function or self.__class__.read_function), during execution the corresponding bound method (self.read_function) will be used.
Note: Calling the synchronous add_attribute method from a coroutine function in an asyncio server may cause a deadlock. Use
await
async_add_attribute()
instead. However, if overriding the synchronous methodinitialize_dynamic_attributes
, then the synchronous add_attribute method must be used, even in asyncio servers.- Parameters:
attr (server.attribute or Attr or AttrData) – the new attribute to be added to the list.
r_meth (callable) – the read method to be called on a read request (if attr is of type server.attribute, then use the fget field in the attr object instead)
w_meth (callable) – the write method to be called on a write request (if attr is writable) (if attr is of type server.attribute, then use the fset field in the attr object instead)
is_allo_meth (callable) – the method that is called to check if it is possible to access the attribute or not (if attr is of type server.attribute, then use the fisallowed field in the attr object instead)
- Returns:
the newly created attribute.
- Return type:
- Raises:
- add_command(self, cmd, device_level=True) cmd
Add a new command to the device command list.
- Parameters:
cmd – the new command to be added to the list
device_level – Set this flag to true if the command must be added for only this device
- Returns:
The command to add
- Return type:
Command
- Raises:
- add_version_info(self, key, value) dict
Method to add information about the module version a device is using
New in version 10.0.0.
- always_executed_hook()
Tango always_executed_hook. Default implementation does nothing
- append_status(self, status, new_line=False)
Appends a string to the device status.
- async async_add_attribute(self, attr, r_meth=None, w_meth=None, is_allo_meth=None) Attr
Add a new attribute to the device attribute list.
Please, note that if you add an attribute to a device at device creation time, this attribute will be added to the device class attribute list. Therefore, all devices belonging to the same class created after this attribute addition will also have this attribute.
If you pass a reference to unbound method for read, write or is_allowed method (e.g. DeviceClass.read_function or self.__class__.read_function), during execution the corresponding bound method (self.read_function) will be used.
- Parameters:
attr (server.attribute or Attr or AttrData) – the new attribute to be added to the list.
r_meth (callable) – the read method to be called on a read request (if attr is of type server.attribute, then use the fget field in the attr object instead)
w_meth (callable) – the write method to be called on a write request (if attr is writable) (if attr is of type server.attribute, then use the fset field in the attr object instead)
is_allo_meth (callable) – the method that is called to check if it is possible to access the attribute or not (if attr is of type server.attribute, then use the fisallowed field in the attr object instead)
- Returns:
the newly created attribute.
- Return type:
- Raises:
New in version 10.0.0.
- async async_remove_attribute(self, attr_name, free_it=False, clean_db=True)
Remove one attribute from the device attribute list.
- Parameters:
- Raises:
New in version 10.0.0.
- check_command_exists(self)
Check that a command is supported by the device and does not need input value.
The method throws an exception if the command is not defined or needs an input value.
- Parameters:
cmd_name (str) – the command name
- Raises:
API_IncompatibleCmdArgumentType –
API_CommandNotFound –
New in PyTango 7.1.2
- create_telemetry_tracer(device_tracer_provider) opentelemetry.trace.Tracer
Factory method returning a Tracer for telemetry.
The default implementation can be overridden.
New in version 10.0.0.
- create_telemetry_tracer_provider(class_name, device_name) opentelemetry.trace.TracerProvider
Factory method returning a TracerProvider for telemetry.
The default implementation can be overridden.
New in version 10.0.0.
- debug_stream(self, msg, *args, source=None)
Sends the given message to the tango debug stream.
Since PyTango 7.1.3, the same can be achieved with:
print(msg, file=self.log_debug)
- Parameters:
msg (str) – the message to be sent to the debug stream
*args – Arguments to format a message string.
source (Callable) – Function that will be inspected for filename and lineno in the log message.
New in version 9.4.2: added source parameter
- delete_device(self)
Delete the device.
- dev_state(self) DevState
Get device state.
Default method to get device state. The behaviour of this method depends on the device state. If the device state is ON or ALARM, it reads the attribute(s) with an alarm level defined, check if the read value is above/below the alarm and eventually change the state to ALARM, return the device state. For all th other device state, this method simply returns the state This method can be redefined in sub-classes in case of the default behaviour does not fullfill the needs.
- dev_status(self) str
Get device status.
Default method to get device status. It returns the contents of the device dev_status field. If the device state is ALARM, alarm messages are added to the device status. This method can be redefined in sub-classes in case of the default behaviour does not fullfill the needs.
- error_stream(self, msg, *args, source=None)
Sends the given message to the tango error stream.
Since PyTango 7.1.3, the same can be achieved with:
print(msg, file=self.log_error)
- Parameters:
msg (str) – the message to be sent to the error stream
*args – Arguments to format a message string.
source (Callable) – Function that will be inspected for filename and lineno in the log message.
New in version 9.4.2: added source parameter
- fatal_stream(self, msg, *args, source=None)
Sends the given message to the tango fatal stream.
Since PyTango 7.1.3, the same can be achieved with:
print(msg, file=self.log_fatal)
- Parameters:
msg (str) – the message to be sent to the fatal stream
*args – Arguments to format a message string.
source (Callable) – Function that will be inspected for filename and lineno in the log message.
New in version 9.4.2: added source parameter
- get_attr_min_poll_period(self) Sequence[str]
Returns the min attribute poll period
- Returns:
the min attribute poll period
- Return type:
Sequence[str]
New in PyTango 7.2.0
- get_attr_poll_ring_depth(self, attr_name) int
Returns the attribute poll ring depth.
- Parameters:
attr_name (str) – the attribute name
- Returns:
the attribute poll ring depth
- Return type:
New in PyTango 7.1.2
- get_attribute_config(self, attr_names) list[DeviceAttributeConfig]
Returns the list of AttributeConfig for the requested names
- Parameters:
attr_names (list[str]) – sequence of str with attribute names
- Returns:
tango.DeviceAttributeConfig
for each requested attribute name- Return type:
- get_attribute_config_2(self, attr_names) list[AttributeConfig_2]
Returns the list of AttributeConfig_2 for the requested names
- get_attribute_config_3(self, attr_name) list[AttributeConfig_3]
Returns the list of AttributeConfig_3 for the requested names
- get_attribute_poll_period(self, attr_name) int
Returns the attribute polling period (ms) or 0 if the attribute is not polled.
- Parameters:
attr_name (str) – attribute name
- Returns:
attribute polling period (ms) or 0 if it is not polled
- Return type:
New in PyTango 8.0.0
- get_cmd_min_poll_period(self) Sequence[str]
Returns the min command poll period.
- Returns:
the min command poll period
- Return type:
Sequence[str]
New in PyTango 7.2.0
- get_cmd_poll_ring_depth(self, cmd_name) int
Returns the command poll ring depth.
New in PyTango 7.1.2
- get_command_poll_period(self, cmd_name) int
Returns the command polling period (ms) or 0 if the command is not polled.
- Parameters:
cmd_name (str) – command name
- Returns:
command polling period (ms) or 0 if it is not polled
- Return type:
New in PyTango 8.0.0
- get_dev_idl_version(self) int
Returns the IDL version.
- Returns:
the IDL version
- Return type:
New in PyTango 7.1.2
- get_device_attr(self) MultiAttribute
Get device multi attribute object.
- Returns:
the device’s MultiAttribute object
- Return type:
- get_device_class(self)
Get device class singleton.
- Returns:
the device class singleton (device_class field)
- Return type:
- get_device_properties(self, ds_class=None)
Utility method that fetches all the device properties from the database and converts them into members of this DeviceImpl.
- Parameters:
ds_class (DeviceClass) – the DeviceClass object. Optional. Default value is None meaning that the corresponding DeviceClass object for this DeviceImpl will be used
- Raises:
- get_exported_flag(self) bool
Returns the state of the exported flag
- Returns:
the state of the exported flag
- Return type:
New in PyTango 7.1.2
- get_logger(self) Logger
Returns the Logger object for this device
- Returns:
the Logger object for this device
- Return type:
Logger
- get_min_poll_period(self) int
Returns the min poll period.
- Returns:
the min poll period
- Return type:
New in PyTango 7.2.0
- get_non_auto_polled_attr(self) Sequence[str]
Returns a COPY of the list of non automatic polled attributes
- Returns:
a COPY of the list of non automatic polled attributes
- Return type:
Sequence[str]
New in PyTango 7.1.2
- get_non_auto_polled_cmd(self) Sequence[str]
Returns a COPY of the list of non automatic polled commands
- Returns:
a COPY of the list of non automatic polled commands
- Return type:
Sequence[str]
New in PyTango 7.1.2
- get_poll_old_factor(self) int
Returns the poll old factor
- Returns:
the poll old factor
- Return type:
New in PyTango 7.1.2
- get_poll_ring_depth(self) int
Returns the poll ring depth
- Returns:
the poll ring depth
- Return type:
New in PyTango 7.1.2
- get_polled_attr(self) Sequence[str]
Returns a COPY of the list of polled attributes
- Returns:
a COPY of the list of polled attributes
- Return type:
Sequence[str]
New in PyTango 7.1.2
- get_polled_cmd(self) Sequence[str]
Returns a COPY of the list of polled commands
- Returns:
a COPY of the list of polled commands
- Return type:
Sequence[str]
New in PyTango 7.1.2
- get_prev_state(self) DevState
Get a COPY of the device’s previous state.
- Returns:
the device’s previous state
- Return type:
- get_state(self) DevState
Get a COPY of the device state.
- Returns:
Current device state
- Return type:
- get_telemetry_tracer() opentelemetry.trace.Tracer
Returns device telemetry tracer, or None if telemetry disabled.
New in version 10.0.0.
- get_version_info(self) dict
Returns a dict with versioning of different modules related to the pytango device.
- Example:
{ "Build.PyTango.Boost": "1.84.0", "Build.PyTango.NumPy": "1.26.4", "Build.PyTango.Python": "3.12.2", "Build.PyTango.cppTango":"10.0.0", "NumPy": "1.26.4", "PyTango": "10.0.0.dev0", "Python": "3.12.2", "cppTango": "10.0.0", "omniORB": "4.3.2", "zmq": "4.3.5" }
- Returns:
modules version dict
- Return type:
New in version 10.0.0.
- info_stream(self, msg, *args, source=None)
Sends the given message to the tango info stream.
Since PyTango 7.1.3, the same can be achieved with:
print(msg, file=self.log_info)
- Parameters:
msg (str) – the message to be sent to the info stream
*args – Arguments to format a message string.
source (Callable) – Function that will be inspected for filename and lineno in the log message.
New in version 9.4.2: added source parameter
- init_device()
Tango init_device method. Default implementation calls
get_device_properties()
- initialize_dynamic_attributes()
Method executed at initializion phase to create dynamic attributes. Default implementation does nothing. Overwrite when necessary.
Note
This method is only called once when the device server starts, after init_device(), but before the device is marked as exported. If the Init command is executed on the device, the initialize_dynamic_attributes() method will not be called again.
- is_device_locked(self) bool
Returns if this device is locked by a client.
- Returns:
True if it is locked or False otherwise
- Return type:
New in PyTango 7.1.2
- is_kernel_tracing_enabled(self) bool
Indicates if telemetry tracing of the cppTango kernel API is enabled.
Always False if telemetry support isn’t compiled into cppTango.
- Returns:
if kernel tracing is enabled
- Return type:
New in version 10.0.0.
- is_polled(self) bool
Returns if it is polled
- Returns:
True if it is polled or False otherwise
- Return type:
New in PyTango 7.1.2
- is_telemetry_enabled(self) bool
Indicates if telemetry tracing is enabled for the device.
Always False if telemetry support isn’t compiled into cppTango.
- Returns:
if device telemetry tracing is enabled
- Return type:
New in version 10.0.0.
- is_there_subscriber(self, att_name, event_type) bool
Check if there is subscriber(s) listening for the event.
This method returns a boolean set to true if there are some subscriber(s) listening on the event specified by the two method arguments. Be aware that there is some delay (up to 600 sec) between this method returning false and the last subscriber unsubscription or crash…
The device interface change event is not supported by this method.
- push_alarm_event(attr_name, *args, **kwargs)
- push_alarm_event(self, attr_name, except)
- push_alarm_event(self, attr_name, data, dim_x=1, dim_y=0)
- push_alarm_event(self, attr_name, str_data, data)
- push_alarm_event(self, attr_name, data, time_stamp, quality, dim_x=1, dim_y=0)
- push_alarm_event(self, attr_name, str_data, data, time_stamp, quality)
Push an alarm event for the given attribute name.
- Parameters:
attr_name (str) – attribute name
data – the data to be sent as attribute event data. Data must be compatible with the attribute type and format. for SPECTRUM and IMAGE attributes, data can be any type of sequence of elements compatible with the attribute type
str_data (str) – special variation for DevEncoded data type. In this case ‘data’ must be a str or an object with the buffer interface.
except (DevFailed) – Instead of data, you may want to send an exception.
dim_x (int) – the attribute x length. Default value is 1
dim_y (int) – the attribute y length. Default value is 0
time_stamp (double) – the time stamp
quality (AttrQuality) – the attribute quality factor
- Raises:
DevFailed – If the attribute data type is not coherent.
- push_archive_event(attr_name, *args, **kwargs)
- push_archive_event(self, attr_name, except)
- push_archive_event(self, attr_name, data, dim_x=1, dim_y=0)
- push_archive_event(self, attr_name, str_data, data)
- push_archive_event(self, attr_name, data, time_stamp, quality, dim_x=1, dim_y=0)
- push_archive_event(self, attr_name, str_data, data, time_stamp, quality)
Push an archive event for the given attribute name.
- Parameters:
attr_name (str) – attribute name
data – the data to be sent as attribute event data. Data must be compatible with the attribute type and format. for SPECTRUM and IMAGE attributes, data can be any type of sequence of elements compatible with the attribute type
str_data (str) – special variation for DevEncoded data type. In this case ‘data’ must be a str or an object with the buffer interface.
except (DevFailed) – Instead of data, you may want to send an exception.
dim_x (int) – the attribute x length. Default value is 1
dim_y (int) – the attribute y length. Default value is 0
time_stamp (double) – the time stamp
quality (AttrQuality) – the attribute quality factor
- Raises:
DevFailed – If the attribute data type is not coherent.
- push_att_conf_event(self, attr)
Push an attribute configuration event.
- Parameters:
attr (Attribute) – the attribute for which the configuration event will be sent.
New in PyTango 7.2.1
- push_change_event(attr_name, *args, **kwargs)
- push_change_event(self, attr_name, except)
- push_change_event(self, attr_name, data, dim_x=1, dim_y=0)
- push_change_event(self, attr_name, str_data, data)
- push_change_event(self, attr_name, data, time_stamp, quality, dim_x=1, dim_y=0)
- push_change_event(self, attr_name, str_data, data, time_stamp, quality)
Push a change event for the given attribute name.
- Parameters:
attr_name (str) – attribute name
data – the data to be sent as attribute event data. Data must be compatible with the attribute type and format. for SPECTRUM and IMAGE attributes, data can be any type of sequence of elements compatible with the attribute type
str_data (str) – special variation for DevEncoded data type. In this case ‘data’ must be a str or an object with the buffer interface.
except (DevFailed) – Instead of data, you may want to send an exception.
dim_x (int) – the attribute x length. Default value is 1
dim_y (int) – the attribute y length. Default value is 0
time_stamp (double) – the time stamp
quality (AttrQuality) – the attribute quality factor
- Raises:
DevFailed – If the attribute data type is not coherent.
- push_data_ready_event(self, attr_name, counter)
Push a data ready event for the given attribute name.
The method needs the attribute name and a “counter” which will be passed within the event
- push_event(attr_name, filt_names, filt_vals, *args, **kwargs)
- push_event(self, attr_name, filt_names, filt_vals, except)
- push_event(self, attr_name, filt_names, filt_vals, data, dim_x=1, dim_y=0)
- push_event(self, attr_name, filt_names, filt_vals, str_data, data)
- push_event(self, attr_name, filt_names, filt_vals, data, time_stamp, quality, dim_x=1, dim_y=0)
- push_event(self, attr_name, filt_names, filt_vals, str_data, data, time_stamp, quality)
Push a user event for the given attribute name.
- Parameters:
attr_name (str) – attribute name
filt_names (Sequence[str]) – unused (kept for backwards compatibility) - pass an empty list.
filt_vals (Sequence[double]) – unused (kept for backwards compatibility) - pass an empty list.
data – the data to be sent as attribute event data. Data must be compatible with the attribute type and format. for SPECTRUM and IMAGE attributes, data can be any type of sequence of elements compatible with the attribute type
str_data (str) – special variation for DevEncoded data type. In this case ‘data’ must be a str or an object with the buffer interface.
dim_x (int) – the attribute x length. Default value is 1
dim_y (int) – the attribute y length. Default value is 0
time_stamp (double) – the time stamp
quality (AttrQuality) – the attribute quality factor
- Raises:
DevFailed – If the attribute data type is not coherent.
- push_pipe_event(self, blob)
Push an pipe event.
- Parameters:
blob – the blob which pipe event will be send.
New in PyTango 9.2.2
- read_attr_hardware(self, attr_list)
Read the hardware to return attribute value(s).
Default method to implement an action necessary on a device to read the hardware involved in a read attribute CORBA call. This method must be redefined in sub-classes in order to support attribute reading
- register_signal(self, signo)
Register a signal.
Register this device as device to be informed when signal signo is sent to to the device server process
- Parameters:
signo (int) – signal identifier
- remove_attribute(self, attr_name)
Remove one attribute from the device attribute list.
Note: Call of synchronous remove_attribute method from a coroutine function in an asyncio server may cause a deadlock. Use
await
async_remove_attribute()
instead. However, if overriding the synchronous methodinitialize_dynamic_attributes
, then the synchronous remove_attribute method must be used, even in asyncio servers.- Parameters:
- Raises:
New in version 9.5.0: free_it parameter. clean_db parameter.
- remove_command(self, cmd_name, free_it=False, clean_db=True)
Remove one command from the device command list.
- classmethod run_server(args=None, **kwargs)
Run the class as a device server. It is based on the tango.server.run method.
The difference is that the device class and server name are automatically given.
- Args:
- args (iterable): args as given in the tango.server.run method
without the server name. If None, the sys.argv list is used
- kwargs: the other keywords argument are as given
in the tango.server.run method.
- server_init_hook()
Tango server_init_hook. Called once the device server admin device (DServer) is exported. Default implementation does nothing.
- set_archive_event(self, attr_name, implemented, detect=True)
Set an implemented flag for the attribute to indicate that the server fires archive events manually, without the polling to be started.
If the detect parameter is set to true, the criteria specified for the archive event are verified and the event is only pushed if they are fullfilled. If detect is set to false the event is fired without any value checking!
- set_attribute_config(self, new_conf) None
Sets attribute configuration locally and in the Tango database
- Parameters:
new_conf (list[
tango.AttributeConfig
]) – The new attribute(s) configuration. One AttributeConfig structure is needed for each attribute to update- Returns:
None
- Return type:
None
New in version 10.0.0.
- set_attribute_config_3(self, new_conf) None
Sets attribute configuration locally and in the Tango database
- Parameters:
new_conf (list[
tango.AttributeConfig_3
]) – The new attribute(s) configuration. One AttributeConfig structure is needed for each attribute to update- Returns:
None
- Return type:
None
- set_change_event(self, attr_name, implemented, detect=True)
Set an implemented flag for the attribute to indicate that the server fires change events manually, without the polling to be started.
If the detect parameter is set to true, the criteria specified for the change event are verified and the event is only pushed if they are fullfilled. If detect is set to false the event is fired without any value checking!
- set_data_ready_event(self, attr_name, implemented)
Set an implemented flag for the attribute to indicate that the server fires data ready events manually.
- set_kernel_tracing_enabled(self, enabled) None
Enable or disable telemetry tracing of cppTango kernel methods, and for high-level PyTango devices, tracing of the PyTango kernel (BaseDevice) methods.
This is a no-op if telemetry support isn’t compiled into cppTango.
- Parameters:
enabled (bool) – True to enable kernel tracing
New in version 10.0.0.
- set_state(self, new_state)
Set device state.
- Parameters:
new_state (DevState) – the new device state
- set_status(self, new_status)
Set device status.
- Parameters:
new_status (str) – the new device status
- set_telemetry_enabled(self, enabled) None
Enable or disable the device’s telemetry interface.
This is a no-op if telemetry support isn’t compiled into cppTango.
- Parameters:
enabled (bool) – True to enable telemetry tracing
New in version 10.0.0.
- signal_handler(self, signo)
Signal handler.
The method executed when the signal arrived in the device server process. This method is defined as virtual and then, can be redefined following device needs.
- stop_poll_attribute(self, attr_name) None
Remove an attribute from the list of polled attributes.
- Parameters:
attr_name (str) – attribute name
- Returns:
None
- Return type:
None
- stop_poll_command(self, cmd_name) None
Remove a command from the list of polled commands.
- Parameters:
cmd_name (str) – cmd_name name
- Returns:
None
- Return type:
None
- stop_polling(self)
- stop_polling(self, with_db_upd)
Stop all polling for a device. if the device is polled, call this method before deleting it.
- Parameters:
with_db_upd (bool) – Is it necessary to update db?
New in PyTango 7.1.2
- unregister_signal(self, signo)
Unregister a signal.
Unregister this device as device to be informed when signal signo is sent to to the device server process
- Parameters:
signo (int) – signal identifier
- warn_stream(self, msg, *args, source=None)
Sends the given message to the tango warn stream.
Since PyTango 7.1.3, the same can be achieved with:
print(msg, file=self.log_warn)
- Parameters:
msg (str) – the message to be sent to the warn stream
*args – Arguments to format a message string.
source (Callable) – Function that will be inspected for filename and lineno in the log message.
New in version 9.4.2: added source parameter
- write_attr_hardware(self)
Write the hardware for attributes.
Default method to implement an action necessary on a device to write the hardware involved in a write attribute. This method must be redefined in sub-classes in order to support writable attribute
- class tango.server.attribute(fget=None, **kwargs)
Declares a new tango attribute in a
Device
. To be used like the python nativeproperty
function. For example, to declare a scalar, tango.DevDouble, read-only attribute called voltage in a PowerSupplyDevice
do:class PowerSupply(Device): voltage = attribute() def read_voltage(self): return 999.999
The same can be achieved with:
class PowerSupply(Device): @attribute def voltage(self): return 999.999
It receives multiple keyword arguments.
parameter
type
default value
description
name
class member name
alternative attribute name
dtype
DevDouble
data type (see Data type equivalence)
dformat
SCALAR
data format
max_dim_x
1
maximum size for x dimension (ignored for SCALAR format)
max_dim_y
0
maximum size for y dimension (ignored for SCALAR and SPECTRUM formats)
display_level
OPERATOR
display level
polling_period
-1
polling period
memorized
False
attribute must be memorized (only applicable to scalar, writeable attributes). If True, the latest write value, i.e., set point, is stored in the Tango database - see also
hw_memorized
parameter. Corresponds to low-leveltango.Attr.set_memorized()
.hw_memorized
False
memorized value will be restored by automatically calling attribute write method at startup, and after each
Init
command call (only applies ifmemorized
is set to True). Corresponds to low-leveltango.Attr.set_memorized_init()
access
READ
read only/ read write / write only access
fget (or fread)
‘read_<attr_name>’
read method name or method object
fset (or fwrite)
‘write_<attr_name>’
write method name or method object
fisallowed
‘is_<attr_name>_allowed’
is allowed method name or method object
label
‘<attr_name>’
attribute label
enum_labels
sequence
None
the list of enumeration labels (enum data type)
doc (or description)
‘’
attribute description
unit
‘’
physical units the attribute value is in
standard_unit
‘’
physical standard unit
display_unit
‘’
physical display unit (hint for clients)
format
‘6.2f’
attribute representation format
min_value
None
minimum allowed value
max_value
None
maximum allowed value
min_alarm
None
minimum value to trigger attribute alarm
max_alarm
None
maximum value to trigger attribute alarm
min_warning
None
minimum value to trigger attribute warning
max_warning
None
maximum value to trigger attribute warning
delta_val
None
delta_t
None
abs_change
None
minimum value change between events that causes event filter to send the event
rel_change
None
minimum relative change between events that causes event filter to send the event (%)
period
None
archive_abs_change
None
archive_rel_change
None
archive_period
None
green_mode
True
Default green mode for read/write/isallowed functions. If True: run with green mode executor, if False: run directly
read_green_mode
‘green_mode’ value
green mode for read function. If True: run with green mode executor, if False: run directly
write_green_mode
‘green_mode’ value
green mode for write function. If True: run with green mode executor, if False: run directly
isallowed_green_mode
‘green_mode’ value
green mode for is allowed function. If True: run with green mode executor, if False: run directly
forwarded
False
the attribute should be forwarded if True
Note
avoid using dformat parameter. If you need a SPECTRUM attribute of say, boolean type, use instead
dtype=(bool,)
.Example of a integer writable attribute with a customized label, unit and description:
class PowerSupply(Device): current = attribute(label="Current", unit="mA", dtype=int, access=AttrWriteType.READ_WRITE, doc="the power supply current") def init_device(self): Device.init_device(self) self._current = -1 def read_current(self): return self._current def write_current(self, current): self._current = current
The same, but using attribute as a decorator:
class PowerSupply(Device): def init_device(self): Device.init_device(self) self._current = -1 @attribute(label="Current", unit="mA", dtype=int) def current(self): """the power supply current""" return 999.999 @current.write def current(self, current): self._current = current
In this second format, defining the write implicitly sets the attribute access to READ_WRITE.
New in version 8.1.7: added green_mode, read_green_mode and write_green_mode options
- tango.server.command(f=None, dtype_in=None, dformat_in=None, doc_in='', dtype_out=None, dformat_out=None, doc_out='', display_level=None, polling_period=None, green_mode=True, fisallowed=None, cmd_green_mode=None, isallowed_green_mode=None)
Declares a new tango command in a
Device
. To be used like a decorator in the methods you want to declare as tango commands. The following example declares commands:void TurnOn(void)
void Ramp(DevDouble current)
DevBool Pressurize(DevDouble pressure)
class PowerSupply(Device): @command def TurnOn(self): self.info_stream('Turning on the power supply') @command(dtype_in=float) def Ramp(self, current): self.info_stream('Ramping on %f...' % current) @command(dtype_in=float, doc_in='the pressure to be set', dtype_out=bool, doc_out='True if it worked, False otherwise') def Pressurize(self, pressure): self.info_stream('Pressurizing to %f...' % pressure) return True
Note
avoid using dformat parameter. If you need a SPECTRUM attribute of say, boolean type, use instead
dtype=(bool,)
.- Parameters:
dtype_in – a data type describing the type of parameter. Default is None meaning no parameter.
dformat_in (AttrDataFormat) – parameter data format. Default is None.
doc_in (str) – parameter documentation
dtype_out – a data type describing the type of return value. Default is None meaning no return value.
dformat_out (AttrDataFormat) – return value data format. Default is None.
doc_out (str) – return value documentation
display_level (DispLevel) – display level for the command (optional)
polling_period (int) – polling period in milliseconds (optional)
green_mode (bool) – DEPRECATED: green mode for command method. If True: run with green mode executor, if False: run directly. See the green_mode parameter deprecation note below for more details.
fisallowed (str or callable) – is allowed method for command
cmd_green_mode (bool) – green mode for command method. If True: run with green mode executor, if False: run directly See the green_mode parameter deprecation note below for more details.
isallowed_green_mode (bool) – green mode for isallowed method. If True: run with green mode executor, if False: run directly See the green_mode parameter deprecation note below for more details.
New in version 8.1.7: added green_mode option
New in version 9.2.0: added display_level and polling_period optional argument
New in version 9.4.0: added fisallowed option
New in version 10.0.0: added cmd_green_mode and isallowed_green_mode options
Changed in version 10.0.0: the way that the green_mode parameter is interpreted was changed to be consistent with the same parameter for attributes. Now it expects bool, which indicates, if methods should be run with executor (green_mode=True, default) or bypass it (green_mode=False) Before it was either green_mode=None - use executor or green_mode=GreenMode.Synchronous - bypass it. However, due python by default casts GreenMode.Synchronous (which is int value 0) to False bool, old code is automatically backward compatible.
Deprecated since version 10.0.0: green_mode parameter is deprecated and may be removed in future. Use cmd_green_mode and isallowed_green_mode parameters instead. The new parameters match how attributes and pipes are defined, offer more flexibility, and are clearer. If you use both old green_mode, and new isallowed_green_mode and cmd_green_mode - the new ones take priority.
- class tango.server.pipe(fget=None, **kwargs)
Declares a new tango pipe in a
Device
. To be used like the python nativeproperty
function.Checkout the pipe data types to see what you should return on a pipe read request and what to expect as argument on a pipe write request.
For example, to declare a read-only pipe called ROI (for Region Of Interest), in a Detector
Device
do:class Detector(Device): ROI = pipe() def read_ROI(self): return ('ROI', ({'name': 'x', 'value': 0}, {'name': 'y', 'value': 10}, {'name': 'width', 'value': 100}, {'name': 'height', 'value': 200}))
The same can be achieved with (also showing that a dict can be used to pass blob data):
class Detector(Device): @pipe def ROI(self): return 'ROI', dict(x=0, y=10, width=100, height=200)
It receives multiple keyword arguments.
parameter
type
default value
description
name
class member name
alternative pipe name
display_level
OPERATOR
display level
access
READ
read only/ read write access
fget (or fread)
‘read_<pipe_name>’
read method name or method object
fset (or fwrite)
‘write_<pipe_name>’
write method name or method object
fisallowed
‘is_<pipe_name>_allowed’
is allowed method name or method object
label
‘<pipe_name>’
pipe label
doc (or description)
‘’
pipe description
green_mode
True
Default green mode for read/write/isallowed functions. If True: run with green mode executor, if False: run directly
read_green_mode
‘green_mode’ value
green mode for read function. If True: run with green mode executor, if False: run directly
write_green_mode
‘green_mode’ value
green mode for write function. If True: run with green mode executor, if False: run directly
isallowed_green_mode
‘green_mode’ value
green mode for is allowed function. If True: run with green mode executor, if False: run directly
The same example with a read-write ROI, a customized label and description:
class Detector(Device): ROI = pipe(label='Region Of Interest', doc='The active region of interest', access=PipeWriteType.PIPE_READ_WRITE) def init_device(self): Device.init_device(self) self.__roi = 'ROI', dict(x=0, y=10, width=100, height=200) def read_ROI(self): return self.__roi def write_ROI(self, roi): self.__roi = roi
The same, but using pipe as a decorator:
class Detector(Device): def init_device(self): Device.init_device(self) self.__roi = 'ROI', dict(x=0, y=10, width=100, height=200) @pipe(label="Region Of Interest") def ROI(self): """The active region of interest""" return self.__roi @ROI.write def ROI(self, roi): self.__roi = roi
In this second format, defining the write / setter implicitly sets the pipe access to READ_WRITE.
New in version 9.2.0.
New in version 9.4.0: added isallowed_green_mode option
- class tango.server.device_property(dtype=None, doc='', mandatory=False, default_value=None, update_db=False)
Declares a new tango device property in a
Device
. To be used like the python nativeproperty
function. For example, to declare a scalar, tango.DevString, device property called host in a PowerSupplyDevice
do:from tango.server import Device, DeviceMeta from tango.server import device_property class PowerSupply(Device): host = device_property(dtype=str) port = device_property(dtype=int, mandatory=True)
- Parameters:
dtype – Data type (see Data types)
doc – property documentation (optional)
(optional (mandatory) – default is False)
default_value – default value for the property (optional)
update_db (bool) – tells if set value should write the value to database. [default: False]
New in version 8.1.7: added update_db option
- class tango.server.class_property(dtype=None, doc='', default_value=None, update_db=False)
Declares a new tango class property in a
Device
. To be used like the python nativeproperty
function. For example, to declare a scalar, tango.DevString, class property called port in a PowerSupplyDevice
do:from tango.server import Device, DeviceMeta from tango.server import class_property class PowerSupply(Device): port = class_property(dtype=int, default_value=9788)
- Parameters:
dtype – Data type (see Data types)
doc – property documentation (optional)
default_value – default value for the property (optional)
update_db (bool) – tells if set value should write the value to database. [default: False]
New in version 8.1.7: added update_db option
- tango.server.run(classes, args=None, msg_stream=<_io.TextIOWrapper name='<stdout>' mode='w' encoding='utf-8'>, verbose=False, util=None, event_loop=None, pre_init_callback=None, post_init_callback=None, green_mode=None, raises=False, err_stream=<_io.TextIOWrapper name='<stderr>' mode='w' encoding='utf-8'>)
Provides a simple way to run a tango server. It handles exceptions by writting a message to the msg_stream.
- Examples:
Example 1: registering and running a PowerSupply inheriting from
Device
:from tango.server import Device, run class PowerSupply(Device): pass run((PowerSupply,))
Example 2: registering and running a MyServer defined by tango classes MyServerClass and MyServer:
from tango import Device_4Impl, DeviceClass from tango.server import run class MyServer(Device_4Impl): pass class MyServerClass(DeviceClass): pass run({'MyServer': (MyServerClass, MyServer)})
Example 3: registering and running a MyServer defined by tango classes MyServerClass and MyServer:
from tango import Device_4Impl, DeviceClass from tango.server import Device, run class PowerSupply(Device): pass class MyServer(Device_4Impl): pass class MyServerClass(DeviceClass): pass run([PowerSupply, [MyServerClass, MyServer]]) # or: run({'MyServer': (MyServerClass, MyServer)})
Note
the order of registration of tango classes defines the order tango uses to initialize the corresponding devices. if using a dictionary as argument for classes be aware that the order of registration becomes arbitrary. If you need a predefined order use a sequence or an OrderedDict.
- Parameters:
classes (Sequence[tango.server.Device] | dict) –
Defines for which Tango Device Classes the server will run. If
dict
is provided, it’s key is the tango class name and value is either:two element sequence:DeviceClass
,DeviceImpl
args (list) – list of command line arguments [default: None, meaning use sys.argv]
msg_stream – stream where to put messages [default: sys.stdout]
util (
Util
) – PyTango Util object [default: None meaning create a Util instance]event_loop (callable) – event_loop callable
pre_init_callback (callable or tuple) – an optional callback that is executed between the calls Util.init and Util.server_init The optional pre_init_callback can be a callable (without arguments) or a tuple where the first element is the callable, the second is a list of arguments (optional) and the third is a dictionary of keyword arguments (also optional).
post_init_callback (callable or tuple) – an optional callback that is executed between the calls Util.server_init and Util.server_run The optional post_init_callback can be a callable (without arguments) or a tuple where the first element is the callable, the second is a list of arguments (optional) and the third is a dictionary of keyword arguments (also optional).
raises (bool) – Disable error handling and propagate exceptions from the server
err_stream – stream where to put catched exceptions [default: sys.stderr]
- Returns:
The Util singleton object
- Return type:
New in version 8.1.2.
Changed in version 8.1.4: when classes argument is a sequence, the items can also be a sequence <TangoClass, TangoClassClass>[, tango class name]
Changed in version 9.2.2: raises argument has been added
Changed in version 9.5.0: pre_init_callback argument has been added
Changed in version 10.0.0: err_stream argument has been added
- tango.server.server_run(classes, args=None, msg_stream=<_io.TextIOWrapper name='<stdout>' mode='w' encoding='utf-8'>, verbose=False, util=None, event_loop=None, pre_init_callback=None, post_init_callback=None, green_mode=None, err_stream=<_io.TextIOWrapper name='<stderr>' mode='w' encoding='utf-8'>)
Since PyTango 8.1.2 it is just an alias to
run()
. Userun()
instead.New in version 8.0.0.
Changed in version 8.0.3: Added util keyword parameter. Returns util object
Changed in version 8.1.1: Changed default msg_stream from stderr to stdout Added event_loop keyword parameter. Returns util object
Changed in version 8.1.2: Added post_init_callback keyword parameter
Deprecated since version 8.1.2: Use
run()
instead.Changed in version 9.5.0: pre_init_callback argument has been added
Changed in version 10.0.0: err_stream argument has been added