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 class of data for this topic.
data	Get or set internally cached data.
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)	Set one or more fields of self.data.
set_start([timeout, wait_done])	Set zero or more command data fields and start a command.
start([data, timeout, wait_done])	Start a command.

Attributes Documentation

DataType

The class of data for this topic.

data

Get or set internally cached data.

Parameters:

data : DataType

New data.

Raises:

TypeError

If data is not an instance of DataType

Notes

You must not modify the returned data, nor assume that it will be constant. If you need a copy then make it yourself.

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 no time limit. This time limit is for the entire command if wait_done is true, else it is for the first acknowledgement after the initial “SAL__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 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)

Set one or more fields of self.data.

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 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. This is not ideal, but is pragmatic because it is difficult to copy SAL topics (see TSS-3195).

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

Set zero or more command data fields and start a command.

Parameters:

timeout : float (optional)

Time limit, in seconds. If None then no time limit. This time limit is for the entire command if wait_done is true, else it is for the first acknowledgement after the initial “SAL__CMD_ACK”.

wait_done : bool (optional)

If True then wait for final command acknowledgement. If False then wait for the first acknowledgement after the initial “SAL__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 data. If None then send the current data.

timeout : float (optional)

Time limit, in seconds. If None then no time limit. This time limit is for the entire command if wait_done is true, else it is for the first acknowledgement after the initial “SAL__CMD_ACK”.

wait_done : bool (optional)

If True then wait for final command acknowledgement. If False then wait for the first acknowledgement after the initial “SAL__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.

TypeError

If data is not None and not an instance of DataType.