Getting started

This page will guide you to explore a running Dish LMC interface from DishManager.

Prerequisites

It is assumed here that you have set up your development environment and a deployed instance of DishLMC with the simulators.

Explore DishLMC Interface from Client

A tango device proxy will be used to drive control and perform monitoring on the deployed server. From the client, the DishManager device server interface can be explored using tango attributes, properties and commands. The detailed interface can be found in the API section.

Explore Attributes and Commands

interface using itango

In [1]: dish_manager = DeviceProxy("mid-dish/dish-manager/SKA001")

# ensure that the device is reachable
In [2]: dish_manager.ping()
Out[2]: 726

In [3]: dish_manager.get_attribute_list()
Out[3]: [a list of all the attributes]

In [4]: dish_manager.get_command_list()
Out[4]: [a list of all the commands]

# this will produce a snapshot of the state of the subservient
# devices. it is a custom commands used mosstly for debugging.
In [5]: print(dish_manager.GetComponentStates())

# on startup, dish manager reports STANDBY_LP
In [6]: dish_manager.dishMode
Out[6] <DishMode.STANDBY_LP: 2>

Tip

All commands begin with uppercase and for attributes, lowercase. However, the client can call a command or read an attribute in any case so long as that name exists on the server’s interface.

Dish Control and Monitoring

Since DishManager fans out commands to sub devices which in turn execute over a relatively “long” period, most of the commands are implemented to run asynchronously. The progress of a command can be tracked on dedicated attributes which have a longrunningcommand_ suffix (this is in addition to the attribute which will report the final state of the Dish).

The specific attribute(s) which is updated for each command is tabulated below. Event subscription will be used to monitor progress on the dishMode and configuredBand transitions in this example.

monitoring and control in itango

In [1]: cb = tango.utils.EventCallback()
   ...: subscription_id = dish_manager.subscribe_event("longrunningcommandprogress", tango.EventType.CHANGE_EVENT, cb)

# request to go to STANDBY_FP, response is a result code and unique id
In [2]: dish_manager.SetStandbyFPMode()
Out[2]: [array([2], dtype=int32), ['1701377289.3152518_92664672841537_SetStandbyFPMode']]

# monitor the events and look out for a message indicating the
# command has completed and check dish mode is STANDBY_FP
In [3]: dish_manager.dishMode
Out[3] <dishMode.STANDBY_FP: 3>

# configure a freq band (only 1 and 2 supported at the moment)
In [4]: dish_manager.ConfigureBand2(True)
Out[4]: [array([2], dtype=int32), ['1701377495.333358_33114815365266_ConfigureBand2']]

# check band is B2 after events show command completed
In [5]: dish_manager.configuredBand
Out[5] <configuredBand.B2: 2>

# request FP again (illegal transition)
In [6]: dish_manager.SetStandbyFPMode()
ERROR (see image below)

Tip

There is a list of transition rules for the various attributes which determine what the final state of the dish (it’s based on what the sub components are reporting). This is where the custom command GetComponentStates is especially useful.

Commands and updated attributes

Commands	Attributes to watch
SetStandbyLPMode SetStandbyFPMode SetOperateMode	dishMode
SetStowMode SetMaintenanceMode	dishMode, desiredPointing, achievedPointing
ConfigureBand [1,2,3,4,,5a,5b]	configuredBand dishMode (transient change to CONFIG and back to previous mode)
SetKValue	kValue
Scan Slew Track	pointingState, desiredPointing, achievedPointing, achievedTargetLock,
TrackStop	pointingState
TrackLoadStaticOff	N/A