Troubleshooting States and Modes

For DishManager most commands will be rejected if the device is not in the correct dishMode. When diagnosing state issues, the core rule is: DishManager aggregates its state from its subservient devices.

Note

Quick checks before diving into specific issues, verify the following:

  • The device is in the expected state and mode

  • All subdevices are reachable.

    • This can be done by evaluating the connection state of each subdevice using a DeviceProxy to DishManager and checking the attributes: spfConnectionState, spfrxConnectionState & dsConnectionState.

  • No errors are present in the device logs.

Scenario 1: Command Rejected

Issue: You attempt to run a command (e.g. Track), with a dishMode at STANDBY-LP and receive a Command Rejected response.

Root Cause: You are trying to execute a command in a dishMode that is does not allow the particular command. For example, you cannot run a Track if the dishMode is in STANDBY-LP, it must first be transitioned to dishmode OPERATE via the one of the ConfigureBand commands.

For more information detailing the conditions under which each dishMode is reported, please refer to the Dish States and Modes ICD available here. Additionally, visit the DishManager command fanout page for a list of preconditions required for specific dishMode transitions.

Resolution: Check the current dishmode using itango.

import tango
dish = tango.DeviceProxy("mid-dish/dish-manager/SKA001")

# Check current mode and state
dish.dishMode

# Try transitioning to the modes for operation
dish.SetStandbyFPMode()

# Init the track table
dish.trackTableLoadMode = TrackTableLoadMode.NEW
dish.programTrackTable = track_table
# Now you should be able to execute the Track command
dish.Track()

Scenario 2: DishManager Stuck in dishMode UNKNOWN

Issue: When trying to issue a command that causes the dishMode to transition through a sequence of states and eventually reach the desired state, in some cases the dishMode reaches and gets stuck in UNKNOWN.

Root Cause: This can occur when one of the subservient devices is not responding or is in an error state, resulting in the dish manager resolving the dish mode to UNKNOWN.

Resolution: To recover from this state attempt to stow the dish using the command SetStowMode on the DishManager interface. Once the dishMode has successfully transitioned to STOW, try transitioning the dish to low or full power mode using the command SetStandbyFPMode or SetStandbyLPMode to get the dishMode into a known state. Also refer to the States and Modes

# Stow the dish to get it into a known state
# Wait for mode STOW, to be reported on the dishMode attribute
dish.Stow()
# Check that Stow command was successful and dish is now in STOW mode
dish.Status()
# Verify that the dish is indeed in STOW mode
dish.dishMode
# Transition to low power mode
dish.SetStandbyLPMode()
# Verify the dish mode is now in a known state i.e STANDBY-LP
dish.dishMode

Tip

Tracking LRC progress during execution

Using a DeviceProxy to the DishManager device, the progress of the current command being executed can be checked by monitoring the Status attribute.

Note

If there are multiple commands in the queue and it is unclear which command was last invoked, we can check what the last command invoked was by reading the lastcommandinvoked attribute.