RemoteCommand¶

class lsst.ts.salobj.topics.RemoteCommand(salinfo, name)¶

Bases: lsst.ts.salobj.topics.WriteTopic

Issue a specific command topic and wait for acknowldgement.

Parameters:	salinfo : `SalInfo` SAL component information name : `str` Command name

Attributes Summary

`DataType`	The type (class) for a message of this topic.
`data`	Internally cached message.
`has_data`	Has `data` ever been set?
`metadata`	Get topic metadata as a `TopicMetadata`, if available, else `None`.

Methods Summary

`close`()	Shut down and release resources.
`next_ackcmd`(ackcmd[, timeout, wait_done])	Wait for the next acknowledement for the command
`put`([data, priority])	Output this topic.
`set`(**kwargs)	Create a new `self.data` and set one or more fields.
`set_start`([timeout, wait_done])	Create a new `self.data`, set zero or more fields, and start the command.
`start`([data, timeout, wait_done])	Start a command.

Attributes Documentation

DataType¶

The type (class) for a message of this topic.

When you read or write a message for this topic you are reading or writing an instance of DataType.

Notes

The preferred way to write a message for a topic is:

RemoteCommand.set_start to start a command.
CommandEvent.set_put to write an event.
CommandTelemetry.set_put to write a telemetry message.

However, it is also possible to use DataType to create a message, then write, it as separate operations. For example, assuming we have a Remote for SAL component “Test”:

# The preferred way to issue a command:
await = remote.cmd_wait.set_put(duration=2, timeout=5)

# But an alternative is to first create the command,
# then send it, as two separate operations:
message = remote.cmd_wait.DataType(duration=2)
await remote.cmd_wait.start(message, timeout=5)

# Or, even more verbosely:
message = remote.cmd_wait.DataType()
message.duration = 2
await remote.cmd_wait.start(message, timeout=5)

data¶

Internally cached message.

Raises:	TypeError If `data` is not an instance of `DataType`

Notes

Do not assume the data will be constant. You can make a copy using copy.copy(data).

has_data¶: Has data ever been set?

metadata¶: Get topic metadata as a TopicMetadata, if available, else None.

Methods Documentation

close()¶

Shut down and release resources.

Intended to be called by SalInfo.close(), since that tracks all topics.

next_ackcmd(ackcmd, timeout=3600, wait_done=True)¶

Wait for the next acknowledement for the command

Parameters:	ackcmd : `SalInfo.AckCmdType` The command acknowledgement returned by the previous wait (e.g. from `start`). timeout : `float`, optional Time limit, in seconds. If None then use `DEFAULT_TIMEOUT`. This time limit is for the entire command if wait_done is true, else it is for the first acknowledgement after the initial “CMD_ACK”. wait_done : `bool`, optional If True then wait for final command acknowledgement. If False then wait until the next command acknowledgement; if that acknowledgement is not final (the ack code is not in `done_ack_codes`), then you will almost certainly want to await `next_ackcmd` again.
Returns:	ackcmd : `SalInfo.AckCmdType` Command acknowledgement.
Raises:	salobj.AckError If the command fails or times out. RuntimeError If the command specified by `seq_num` is unknown or has already finished.

put(data=None, priority=0)¶

Output this topic.

Parameters:	data : `self.DataType` or `None` New message data to replace `self.data`, if any. priority : `int`, optional Priority; used to set the priority field of events. Ignored for commands and telemetry.
Raises:	TypeError If `data` is not None and not an instance of `DataType`.

set(**kwargs)¶

Create a new self.data and set one or more fields.

Parameters:	**kwargs : `dict` [`str`, `any`] Dict of field name: new value for that field: Any key whose value is `None` is checked for existence, but the value of the field is not changed. If the field being set is an array then the value must either be an array of the same length or a scalar (which replaces every element of the array).
Returns:	did_change : `bool` True if `self.data` was changed, or if this was the first call to `set`.
Raises:	AttributeError If the topic does not have the specified field. ValueError If the field cannot be set to the specified value.

Notes

If one or more fields cannot be set, the data may be partially updated.

set_start(timeout=3600, wait_done=True, **kwargs)¶

Create a new self.data, set zero or more fields, and start the command.

Parameters:	timeout : `float`, optional Time limit, in seconds. If None then use `DEFAULT_TIMEOUT`. This time limit is for the entire command if `wait_done` is true, else it is for the first acknowledgement after the initial `CMD_ACK`. If the command is acknowledged with `CMD_INPROGRESS` then the timeout is extended by the timeout value in the acknowledgement. Thus a slow command will not need a long timeout, so long as the command issues a `CMD_INPROGRESS` acknowledgement with a reasonable `timeout` value. wait_done : `bool`, optional If True then wait for final command acknowledgement. If False then wait for the first acknowledgement after the initial “CMD_ACK”; if that acknowledgement is not final (the ack code is not in done_ack_codes), then you will almost certainly want to await `next_ackcmd`. **kwargs : `dict` [`str`, `any`] The remaining keyword arguments are field name = new value for that field. See `set` for more information about values.
Returns:	ackcmd : `SalInfo.AckCmdType` Command acknowledgement.
Raises:	salobj.AckError If the command fails. salobj.AckTimeoutError If the command times out. TypeError If `data` is not None and not an instance of `DataType`.

start(data=None, timeout=3600, wait_done=True)¶

Start a command.

Parameters:	data : `self.DataType`, optional Command message. If `None` then send the current `self.data`. timeout : `float`, optional Time limit, in seconds. If None then use `DEFAULT_TIMEOUT`. This time limit is for the entire command if `wait_done` is true, else it is for the first acknowledgement after the initial `CMD_ACK`. If the command is acknowledged with `CMD_INPROGRESS` then the timeout is extended by the timeout value in the acknowledgement. Thus a slow command will not need a long timeout, so long as the command issues a `CMD_INPROGRESS` acknowledgement with a reasonable `timeout` value. wait_done : `bool`, optional If True then wait for final command acknowledgement. If False then wait for the first acknowledgement after the initial “CMD_ACK”; if that acknowledgement is not final (the ack code is not in done_ack_codes), then you will almost certainly want to await `next_ackcmd`.
Returns:	ackcmd : `SalInfo.AckCmdType` Command acknowledgement.
Raises:	salobj.AckError If the command fails. salobj.AckTimeoutError If the command times out. RuntimeError If the `salinfo` has not started reading. TypeError If `data` is not None and not an instance of `DataType`.

Navigation

RemoteCommand¶