org.lsst.ccs.subsystem.shutter

Class BrakePowerMonitor

java.lang.Object

org.lsst.ccs.subsystem.shutter.BrakePowerMonitor

All Implemented Interfaces:

EventListener, org.lsst.ccs.framework.HasLifecycle, org.lsst.ccs.messaging.MessageListener, org.lsst.ccs.messaging.StatusMessageListener, org.lsst.ccs.services.alert.AlertListener

public class BrakePowerMonitor
extends Object
implements org.lsst.ccs.framework.HasLifecycle, org.lsst.ccs.messaging.StatusMessageListener, org.lsst.ccs.services.alert.AlertListener

Generates brakePowerChange() events for the central state machine based on status messages sent by a target subsystem, normally the quadbox subsystem (see org-lsst-ccs-subsystem-power). We assume that brake power has been lost if the target subsystem does any of the following:

Goes off-line. Sends a power status message in which the shutter brake voltage is too low. Raises a shutter brake power-loss alert of level higher than NOMINAL.

We assume that brake power has been restored if the target subsystem:

Sends a power status message in which the shutter brake voltage is high enough. Clears an outstanding shutter brake power-loss alert or reduces its level to NOMINAL.

It's not enough for the target subsystem to be on-line; we need to get a positive indication that brake power is on.

The brakeVoltageKey configuration parameter contains the name of the PDU channel supplying the voltage. It's used as the key for the voltage value in the KeyValueDataList published by the quadbox subsystem periodically. It's also use as the ID of the alert raised to signal problems with the voltage.

The quadbox subsystem is recognized not by name but by it's having an agent property named PowerAgentProperties.QUAD_BOX_AGENT which is transmitted with all of its messages.

Since the callbacks used to monitor the status bus should not block and the order of events must be preserved, we add power-is-on flags to an unbounded queue which is read by a dedicated task. The task undertakes to send the required events to the central state machine and waits for the state machine to reply to each event before sending the next.

Author:

tether