Package org.lsst.ccs.subsystem.shutter.plc

This package implements the conversion of messages that are sent and received from the Beckhoff PLC controller via ADS.

See: Description

Class Summary

Class	Description
CalibDone	Contains a CalibDone message sent from the PLC.
Calibrate	Signals the PLC to start a calibration.
ChangeAxisEnablePLC	Signals the PLC to change the enable state of an axis.
ChangeBrakeState	Signals the PLC to engage or release a brake.
ClearAllFaultsPLC	Signals the PLC to clear all axis faults.
ClearAxisFaultsPLC	Signals the PLC to clear faults on one of the axes.
CloseShutter	Signals the PLC to start closing the shutter.
Disable	Holds a Disable message sent from the PLC.
DisableAllAxesPLC	Signals the PLC to disable all axes.
Enable	Holds an Enable message sent from the PLC.
EnableAllAxesPLC	Signals the PLC to enable all axes.
Error	Holds an Error message sent from the PLC.
GoToProd	Signals the PLC enter the Prod state.
HomeAxisPLC	Signals the PLC to home one of the axes.
Ignored	Holds an Ignored message from the PLC.
MotionDonePLC	Contains a motion-done message sent from the PLC.
MoveAxisAbsolutePLC	Signals the PLC to move one axis to a given coordinate.
MoveAxisRelativePLC	Signals the PLC to move one axis to a given distance from its current coordinate at the time the command is actually executed.
MsgToCCS	The base class for all messages sent from the PLC task to CCS.
MsgToPLC	The base class for all messages to be sent to the PLC.
OpenShutter	Signals the PLC to start opening the shutter.
PLCMsg	The base class for all messages sent CCS and PLC in either direction.
Reset	Signals to the PLC to go through its reset sequence.
ShutterStatusPLC	Holds a ShutterStatusPLC message sent from the PLC.
TakeExposure	Signals the PLC to take an exposure.
Timer	Holds a Timer message sent from the PLC.
Tools	Provides some small utility functions.

Enum Summary

Enum	Description
BladeSetPosition	Names of several blade set positions of special importance.
ChangeBrakeState.State	Possible brake states.
Direction	The possible directions of travel for the shutter.
Ignored.Reason	The set of possible reasons for the PLC sending the Ignored message.

Package org.lsst.ccs.subsystem.shutter.plc Description

This package implements the conversion of messages that are sent and received from the Beckhoff PLC controller via ADS. Most of the classes represent messages and inherit from one of two abstract classes:

• PLCMsg defines the version number associated with the entire set of messages and provides an instance fields to hold it. Messages sent from the PLC to the CCS subsystem inherit directly from it.
• MsgToPLC inherits from PLCMsg and is the base class for all messages sent from CCS to PLC. It provides fields containing the message identification information that the PLC code requires in order to detect when a new message of the given type has arrived. It also contains the message sequence counter and the UUID for the subsystem.

Every message class has a constructor that can decode the PLC (ADS) form of the message and set the instance fields accordingly. Each also has an encode() method which implements the reverse transformation. Neither the constructor nor encode() resets the current position of the byte buffers used to hold the PLC form of the message. Both the decoding constructor and the encoding method are provided in order to facilitate testing; in normal use either one or the other is used. For the same reason each message class also has a constructor that takes the values of instance fields directly if there are any.

See the subsystem manual for a more detailed description of the communication between the subsystem and the PLC controller.