AttributeProxy

class tango.AttributeProxy(*args, **kwds)

AttributeProxy is the high level Tango object which provides the client with an easy-to-use interface to TANGO attributes.

To create an AttributeProxy, a complete attribute name must be set in the object constructor.

Example:

att = AttributeProxy(“tango/tangotest/1/long_scalar”)

Note: PyTango implementation of AttributeProxy is in part a python reimplementation of the AttributeProxy found on the C++ API.

delete_property(self, value)None

Delete a the given of properties for this attribute. This method accepts the following types as value parameter:

  1. string [in] - single property to be deleted

  2. tango.DbDatum [in] - single property data to be deleted

  3. tango.DbData [in] - several property data to be deleted

  4. sequence<string> [in]- several property data to be deleted

  5. sequence<DbDatum> [in] - several property data to be deleted

  6. dict<str, obj> [in] - keys are property names to be deleted (values are ignored)

  7. dict<str, DbDatum> [in] - several DbDatum.name are property names to be deleted (keys are ignored)

Parameters
value

can be one of the following:

  1. string [in] - single property data to be deleted

  2. tango.DbDatum [in] - single property data to be deleted

  3. tango.DbData [in] - several property data to be deleted

  4. sequence<string> [in]- several property data to be deleted

  5. sequence<DbDatum> [in] - several property data to be deleted

  6. dict<str, obj> [in] - keys are property names to be deleted (values are ignored)

  7. dict<str, DbDatum> [in] - several DbDatum.name are property names to be deleted (keys are ignored)

Return

None

Throws

ConnectionFailed, CommunicationFailed DevFailed from device (DB_SQLError), TypeError

event_queue_size(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().event_queue_size(…)

For convenience, here is the documentation of DeviceProxy.event_queue_size(…):

event_queue_size(self, event_id) -> int

Returns the number of stored events in the event reception buffer. After every call to DeviceProxy.get_events(), the event queue size is 0. During event subscription the client must have chosen the ‘pull model’ for this event. event_id is the event identifier returned by the DeviceProxy.subscribe_event() method.

Parameters
event_id

(int) event identifier

Return

an integer with the queue size

Throws

EventSystemFailed

New in PyTango 7.0.0

get_config(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().get_attribute_config(self.name(), …)

For convenience, here is the documentation of DeviceProxy.get_attribute_config(…):

get_attribute_config( self, name) -> AttributeInfoEx

Return the attribute configuration for a single attribute.

Parameters
name

(str) attribute name

Return

(AttributeInfoEx) Object containing the attribute information

Throws

ConnectionFailed, CommunicationFailed, DevFailed from device

Deprecated: use get_attribute_config_ex instead

get_attribute_config( self, names) -> AttributeInfoList

Return the attribute configuration for the list of specified attributes. To get all the attributes pass a sequence containing the constant tango.:class:constants.AllAttr

Parameters
names

(sequence<str>) attribute names

Return

(AttributeInfoList) Object containing the attributes information

Throws

ConnectionFailed, CommunicationFailed, DevFailed from device, TypeError

Deprecated: use get_attribute_config_ex instead

get_device_proxy(self)DeviceProxy

A method which returns the device associated to the attribute

Parameters

None

Return

(DeviceProxy)

get_events(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().get_events(…)

For convenience, here is the documentation of DeviceProxy.get_events(…):

get_events( event_id, callback=None, extract_as=Numpy) -> None

The method extracts all waiting events from the event reception buffer.

If callback is not None, it is executed for every event. During event subscription the client must have chosen the pull model for this event. The callback will receive a parameter of type EventData, AttrConfEventData or DataReadyEventData depending on the type of the event (event_type parameter of subscribe_event).

If callback is None, the method extracts all waiting events from the event reception buffer. The returned event_list is a vector of EventData, AttrConfEventData or DataReadyEventData pointers, just the same data the callback would have received.

Parameters
event_id

(int) is the event identifier returned by the DeviceProxy.subscribe_event() method.

callback

(callable) Any callable object or any object with a “push_event” method.

extract_as

(ExtractAs)

Return

None

Throws

EventSystemFailed, TypeError, ValueError

See Also

subscribe_event

New in PyTango 7.0.0

get_last_event_date(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().get_last_event_date(…)

For convenience, here is the documentation of DeviceProxy.get_last_event_date(…):

get_last_event_date(self, event_id) -> TimeVal

Returns the arrival time of the last event stored in the event reception buffer. After every call to DeviceProxy:get_events(), the event reception buffer is empty. In this case an exception will be returned. During event subscription the client must have chosen the ‘pull model’ for this event. event_id is the event identifier returned by the DeviceProxy.subscribe_event() method.

Parameters
event_id

(int) event identifier

Return

(tango.TimeVal) representing the arrival time

Throws

EventSystemFailed

New in PyTango 7.0.0

get_poll_period(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().get_attribute_poll_period(self.name(), …)

For convenience, here is the documentation of DeviceProxy.get_attribute_poll_period(…):

get_attribute_poll_period(self, attr_name) -> int

Return the attribute polling period.

Parameters
attr_name

(str) attribute name

Return

polling period in milliseconds

get_property(self, propname, value) → DbData

Get a (list) property(ies) for an attribute.

This method accepts the following types as propname parameter: 1. string [in] - single property data to be fetched 2. sequence<string> [in] - several property data to be fetched 3. tango.DbDatum [in] - single property data to be fetched 4. tango.DbData [in,out] - several property data to be fetched. 5. sequence<DbDatum> - several property data to be feteched

Note: for cases 3, 4 and 5 the ‘value’ parameter if given, is IGNORED.

If value is given it must be a tango.DbData that will be filled with the property values

Parameters
propname

(str) property(ies) name(s)

value

(tango.DbData) (optional, default is None meaning that the method will create internally a tango.DbData and return it filled with the property values

Return

(DbData) containing the property(ies) value(s). If a tango.DbData is given as parameter, it returns the same object otherwise a new tango.DbData is returned

Throws

NonDbDevice, ConnectionFailed (with database), CommunicationFailed (with database), DevFailed from database device

get_transparency_reconnection(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().get_transparency_reconnection(…)

For convenience, here is the documentation of DeviceProxy.get_transparency_reconnection(…):

get_transparency_reconnection(self) -> bool

Returns the device transparency reconnection flag.

Parameters

None

Return

(bool) True if transparency reconnection is set or False otherwise

history(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().attribute_history(self.name(), …)

For convenience, here is the documentation of DeviceProxy.attribute_history(…):

attribute_history(self, attr_name, depth, extract_as=ExtractAs.Numpy) -> sequence<DeviceAttributeHistory>

Retrieve attribute history from the attribute polling buffer. See chapter on Advanced Feature for all details regarding polling

Parameters
attr_name

(str) Attribute name.

depth

(int) The wanted history depth.

extract_as

(ExtractAs)

Return

This method returns a vector of DeviceAttributeHistory types.

Throws

NonSupportedFeature, ConnectionFailed, CommunicationFailed, DevFailed from device

is_event_queue_empty(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().is_event_queue_empty(…)

For convenience, here is the documentation of DeviceProxy.is_event_queue_empty(…):

is_event_queue_empty(self, event_id) -> bool

Returns true when the event reception buffer is empty. During event subscription the client must have chosen the ‘pull model’ for this event. event_id is the event identifier returned by the DeviceProxy.subscribe_event() method.

Parameters
event_id

(int) event identifier

Return

(bool) True if queue is empty or False otherwise

Throws

EventSystemFailed

New in PyTango 7.0.0

is_polled(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().is_attribute_polled(self.name(), …)

For convenience, here is the documentation of DeviceProxy.is_attribute_polled(…):

is_attribute_polled(self, attr_name) -> bool

True if the attribute is polled.

Parameters
attr_name

(str) attribute name

Return

boolean value

name(self)str

Returns the attribute name

Parameters

None

Return

(str) with the attribute name

ping(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().ping(…)

For convenience, here is the documentation of DeviceProxy.ping(…):

ping(self) -> int

A method which sends a ping to the device

Parameters

None

Return

(int) time elapsed in microseconds

Throws

exception if device is not alive

poll(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().poll_attribute(self.name(), …)

For convenience, here is the documentation of DeviceProxy.poll_attribute(…):

poll_attribute(self, attr_name, period) -> None

Add an attribute to the list of polled attributes.

Parameters
attr_name

(str) attribute name

period

(int) polling period in milliseconds

Return

None

put_property(self, value)None

Insert or update a list of properties for this attribute. This method accepts the following types as value parameter: 1. tango.DbDatum - single property data to be inserted 2. tango.DbData - several property data to be inserted 3. sequence<DbDatum> - several property data to be inserted 4. dict<str, DbDatum> - keys are property names and value has data to be inserted 5. dict<str, seq<str>> - keys are property names and value has data to be inserted 6. dict<str, obj> - keys are property names and str(obj) is property value

Parameters
value

can be one of the following: 1. tango.DbDatum - single property data to be inserted 2. tango.DbData - several property data to be inserted 3. sequence<DbDatum> - several property data to be inserted 4. dict<str, DbDatum> - keys are property names and value has data to be inserted 5. dict<str, seq<str>> - keys are property names and value has data to be inserted 6. dict<str, obj> - keys are property names and str(obj) is property value

Return

None

Throws

ConnectionFailed, CommunicationFailed DevFailed from device (DB_SQLError), TypeError

read(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().read_attribute(self.name(), …)

For convenience, here is the documentation of DeviceProxy.read_attribute(…):

read_attribute(self, attr_name, extract_as=ExtractAs.Numpy, green_mode=None, wait=True, timeout=None) -> DeviceAttribute

Read a single attribute.

Parameters
attr_name

(str) The name of the attribute to read.

extract_as

(ExtractAs) Defaults to numpy.

green_mode

(GreenMode) Defaults to the current DeviceProxy GreenMode. (see get_green_mode() and set_green_mode()).

wait

(bool) whether or not to wait for result. If green_mode is Synchronous, this parameter is ignored as it always waits for the result. Ignored when green_mode is Synchronous (always waits).

timeout

(float) The number of seconds to wait for the result. If None, then there is no limit on the wait time. Ignored when green_mode is Synchronous or wait is False.

Return

(DeviceAttribute)

Throws

ConnectionFailed, CommunicationFailed, DevFailed from device TimeoutError (green_mode == Futures) If the future didn’t finish executing before the given timeout. Timeout (green_mode == Gevent) If the async result didn’t finish executing before the given timeout.

Changed in version 7.1.4: For DevEncoded attributes, before it was returning a DeviceAttribute.value as a tuple (format<str>, data<str>) no matter what was the extract_as value was. Since 7.1.4, it returns a (format<str>, data<buffer>) unless extract_as is String, in which case it returns (format<str>, data<str>).

Changed in version 8.0.0: For DevEncoded attributes, now returns a DeviceAttribute.value as a tuple (format<str>, data<bytes>) unless extract_as is String, in which case it returns (format<str>, data<str>). Carefull, if using python >= 3 data<str> is decoded using default python utf-8 encoding. This means that PyTango assumes tango DS was written encapsulating string into utf-8 which is the default python encoding.

New in version 8.1.0: green_mode parameter. wait parameter. timeout parameter.

read_asynch(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().read_attribute_asynch(self.name(), …)

For convenience, here is the documentation of DeviceProxy.read_attribute_asynch(…):

read_attribute_asynch( self, attr_name) -> int read_attribute_asynch( self, attr_name, callback) -> None

Shortcut to self.read_attributes_asynch([attr_name], cb)

New in PyTango 7.0.0

read_reply(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().read_attribute_reply(…)

For convenience, here is the documentation of DeviceProxy.read_attribute_reply(…):

read_attribute_reply( self, id, extract_as) -> int read_attribute_reply( self, id, timeout, extract_as) -> None

Shortcut to self.read_attributes_reply()[0]

New in PyTango 7.0.0

set_config(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().set_attribute_config(…)

For convenience, here is the documentation of DeviceProxy.set_attribute_config(…):

set_attribute_config( self, attr_info) -> None

Change the attribute configuration for the specified attribute

Parameters
attr_info

(AttributeInfo) attribute information

Return

None

Throws

ConnectionFailed, CommunicationFailed, DevFailed from device, TypeError

set_attribute_config( self, attr_info_ex) -> None

Change the extended attribute configuration for the specified attribute

Parameters
attr_info_ex

(AttributeInfoEx) extended attribute information

Return

None

Throws

ConnectionFailed, CommunicationFailed, DevFailed from device, TypeError

set_attribute_config( self, attr_info) -> None

Change the attributes configuration for the specified attributes

Parameters
attr_info

(sequence<AttributeInfo>) attributes information

Return

None

Throws

ConnectionFailed, CommunicationFailed, DevFailed from device, TypeError

set_attribute_config( self, attr_info_ex) -> None

Change the extended attributes configuration for the specified attributes

Parameters
attr_info_ex

(sequence<AttributeInfoListEx>) extended attributes information

Return

None

Throws

ConnectionFailed, CommunicationFailed, DevFailed from device, TypeError

set_transparency_reconnection(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().set_transparency_reconnection(…)

For convenience, here is the documentation of DeviceProxy.set_transparency_reconnection(…):

set_transparency_reconnection(self, yesno) -> None

Set the device transparency reconnection flag

Parameters

” - val : (bool) True to set transparency reconnection ” or False otherwise

Return

None

state(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().state(…)

For convenience, here is the documentation of DeviceProxy.state(…): state (self) -> DevState

A method which returns the state of the device.

Parameters

None

Return

(DevState) constant

Example
dev_st = dev.state()
if dev_st == DevState.ON : ...
status(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().status(…)

For convenience, here is the documentation of DeviceProxy.status(…): status (self) -> str

A method which returns the status of the device as a string.

Parameters

None

Return

(str) describing the device status

stop_poll(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().stop_poll_attribute(self.name(), …)

For convenience, here is the documentation of DeviceProxy.stop_poll_attribute(…):

stop_poll_attribute(self, attr_name) -> None

Remove an attribute from the list of polled attributes.

Parameters
attr_name

(str) attribute name

Return

None

subscribe_event(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().subscribe_event(self.name(), …)

For convenience, here is the documentation of DeviceProxy.subscribe_event(…):

subscribe_event(event_type, cb, stateless=False, green_mode=None) -> int

The client call to subscribe for event reception in the push model. The client implements a callback method which is triggered when the event is received. This method is currently used device interface change events only.

Parameters
event_type

(EventType) Is the event reason and must be on the enumerated values: * EventType.INTERFACE_CHANGE_EVENT

callback

(callable) Is any callable object or an object with a callable “push_event” method.

stateless

(bool) When the this flag is set to false, an exception will be thrown when the event subscription encounters a problem. With the stateless flag set to true, the event subscription will always succeed, even if the corresponding device server is not running. The keep alive thread will try every 10 seconds to subscribe for the specified event. At every subscription retry, a callback is executed which contains the corresponding exception

green_mode

the corresponding green mode (default is GreenMode.Synchronous)

Return

An event id which has to be specified when unsubscribing from this event.

Throws

EventSystemFailed, TypeError

subscribe_event(self, attr_name, event, callback, filters=[], stateless=False, extract_as=Numpy, green_mode=None) -> int

The client call to subscribe for event reception in the push model. The client implements a callback method which is triggered when the event is received. Filtering is done based on the reason specified and the event type. For example when reading the state and the reason specified is “change” the event will be fired only when the state changes. Events consist of an attribute name and the event reason. A standard set of reasons are implemented by the system, additional device specific reasons can be implemented by device servers programmers.

Parameters
attr_name

(str) The device attribute name which will be sent as an event e.g. “current”.

event_type

(EventType) Is the event reason and must be on the enumerated values: * EventType.CHANGE_EVENT * EventType.PERIODIC_EVENT * EventType.ARCHIVE_EVENT * EventType.ATTR_CONF_EVENT * EventType.DATA_READY_EVENT * EventType.USER_EVENT

callback

(callable) Is any callable object or an object with a callable “push_event” method.

filters

(sequence<str>) A variable list of name,value pairs which define additional filters for events.

stateless

(bool) When the this flag is set to false, an exception will be thrown when the event subscription encounters a problem. With the stateless flag set to true, the event subscription will always succeed, even if the corresponding device server is not running. The keep alive thread will try every 10 seconds to subscribe for the specified event. At every subscription retry, a callback is executed which contains the corresponding exception

extract_as

(ExtractAs)

green_mode

the corresponding green mode (default is GreenMode.Synchronous)

Return

An event id which has to be specified when unsubscribing from this event.

Throws

EventSystemFailed, TypeError

subscribe_event(self, attr_name, event, queuesize, filters=[], stateless=False, green_mode=None) -> int

The client call to subscribe for event reception in the pull model. Instead of a callback method the client has to specify the size of the event reception buffer.

The event reception buffer is implemented as a round robin buffer. This way the client can set-up different ways to receive events:

  • Event reception buffer size = 1 : The client is interested only in the value of the last event received. All other events that have been received since the last reading are discarded.

  • Event reception buffer size > 1 : The client has chosen to keep an event history of a given size. When more events arrive since the last reading, older events will be discarded.

  • Event reception buffer size = ALL_EVENTS : The client buffers all received events. The buffer size is unlimited and only restricted by the available memory for the client.

All other parameters are similar to the descriptions given in the other subscribe_event() version.

unsubscribe_event(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().unsubscribe_event(…)

For convenience, here is the documentation of DeviceProxy.unsubscribe_event(…):

unsubscribe_event(self, event_id) -> None

Unsubscribes a client from receiving the event specified by event_id.

Parameters
event_id

(int) is the event identifier returned by the DeviceProxy::subscribe_event(). Unlike in TangoC++ we chech that the event_id has been subscribed in this DeviceProxy.

Return

None

Throws

EventSystemFailed, KeyError

write(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().write_attribute(self.name(), …)

For convenience, here is the documentation of DeviceProxy.write_attribute(…):

write_attribute(self, attr_name, value, green_mode=None, wait=True, timeout=None) -> None write_attribute(self, attr_info, value, green_mode=None, wait=True, timeout=None) -> None

Write a single attribute.

Parameters
attr_name

(str) The name of the attribute to write.

attr_info

(AttributeInfo)

value

The value. For non SCALAR attributes it may be any sequence of sequences.

green_mode

(GreenMode) Defaults to the current DeviceProxy GreenMode. (see get_green_mode() and set_green_mode()).

wait

(bool) whether or not to wait for result. If green_mode is Synchronous, this parameter is ignored as it always waits for the result. Ignored when green_mode is Synchronous (always waits).

timeout

(float) The number of seconds to wait for the result. If None, then there is no limit on the wait time. Ignored when green_mode is Synchronous or wait is False.

Throws

ConnectionFailed, CommunicationFailed, DeviceUnlocked, DevFailed from device TimeoutError (green_mode == Futures) If the future didn’t finish executing before the given timeout. Timeout (green_mode == Gevent) If the async result didn’t finish executing before the given timeout.

New in version 8.1.0: green_mode parameter. wait parameter. timeout parameter.

write_asynch(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().write_attribute_asynch(…)

For convenience, here is the documentation of DeviceProxy.write_attribute_asynch(…):

write_attributes_asynch( self, values) -> int write_attributes_asynch( self, values, callback) -> None

Shortcut to self.write_attributes_asynch([attr_name, value], cb)

New in PyTango 7.0.0

write_read(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().write_read_attribute(self.name(), …)

For convenience, here is the documentation of DeviceProxy.write_read_attribute(…):

write_read_attribute(self, attr_name, value, extract_as=ExtractAs.Numpy, green_mode=None, wait=True, timeout=None) -> DeviceAttribute

Write then read a single attribute in a single network call. By default (serialisation by device), the execution of this call in the server can’t be interrupted by other clients.

Parameters

see write_attribute(attr_name, value)

Return

A tango.DeviceAttribute object.

Throws

ConnectionFailed, CommunicationFailed, DeviceUnlocked, DevFailed from device, WrongData TimeoutError (green_mode == Futures) If the future didn’t finish executing before the given timeout. Timeout (green_mode == Gevent) If the async result didn’t finish executing before the given timeout.

New in PyTango 7.0.0

New in version 8.1.0: green_mode parameter. wait parameter. timeout parameter.

write_reply(*args, **kwds)
This method is a simple way to do:

self.get_device_proxy().write_attribute_reply(…)

For convenience, here is the documentation of DeviceProxy.write_attribute_reply(…):

write_attribute_reply(self, id) -> None

Check if the answer of an asynchronous write_attribute is arrived (polling model). If the reply is arrived and if it is a valid reply, the call returned. If the reply is an exception, it is re-thrown by this call. An exception is also thrown in case of the reply is not yet arrived.

Parameters
id

(int) the asynchronous call identifier.

Return

None

Throws

AsynCall, AsynReplyNotArrived, CommunicationFailed, DevFailed from device.

New in PyTango 7.0.0

write_attribute_reply(self, id, timeout) -> None

Check if the answer of an asynchronous write_attribute is arrived (polling model). id is the asynchronous call identifier. If the reply is arrived and if it is a valid reply, the call returned. If the reply is an exception, it is re-thrown by this call. If the reply is not yet arrived, the call will wait (blocking the process) for the time specified in timeout. If after timeout milliseconds, the reply is still not there, an exception is thrown. If timeout is set to 0, the call waits until the reply arrived.

Parameters
id

(int) the asynchronous call identifier.

timeout

(int) the timeout

Return

None

Throws

AsynCall, AsynReplyNotArrived, CommunicationFailed, DevFailed from device.

New in PyTango 7.0.0