MCCS Power States

Overview

This document details the power states within the MCCS subsystem, focusing on how these states are determined based on the power state of subservient devices or the hardware directly controlled by a device. MCCS devices have 5 states:

  1. On: The device or hardware is fully powered and operational.

  2. Off: The device or hardware is powered down. This state is not always implemented if power-off control is unavailable.

  3. Standby: The device or hardware is in a low-power state, with some components powered off and others remaining on.

  4. Unknown: The device is in an error state because it cannot accurately determine the power state of its hardware or its subservient devices.

  5. Fault: The device is in an error state where the expected power state conflicts with the actual power state of its hardware or subservient devices.

Power State Logic by Repository

Main Repository

MccsStation

  • On: The MccsStation is On if both the SpsStation and FieldStation are On.

  • Standby: The MccsStation is Standby if both the SpsStation and FieldStation are Standby.

  • Off: The MccsStation is Off if both the SpsStation and FieldStation are Off.

  • Unknown: The MccsStation is Unknown if the above conditions are not met. This state is common due to mixed power states between the SpsStation and FieldStation.

MccsController

  • On: The MccsController is On if all controlled MccsStation devices are On.

  • Standby: The MccsController is Standby if all controlled MccsStation devices are Standby.

  • Off: The MccsController is Off if all controlled MccsStation devices are Off.

  • Unknown: The MccsController is Unknown if any controlled MccsStation device is Unknown. This state is common due to mixed states across stations.

SPSHW Repository

SpsStation

  • On: The SpsStation is On if all MccsTile devices are On and all MccsSubrack devices are On.

  • Standby: The SpsStation is Standby if all MccsTile devices are Off and all MccsSubrack devices are On.

  • Off: The SpsStation is Off if all MccsTile devices are Off and all MccsSubrack devices are Off. This state is currently unimplemented as subracks cannot be powered off.

  • Unknown: The SpsStation is Unknown if the above conditions are not met. Future work may redefine the On state to apply if any tiles are on, provided all subracks are on.

MccsTile

  • On/Off: MccsTile devices are either On or Off, depending on the power supplied by the MccsSubrack. They do not have a Standby state.

  • Fault: As MccsTile devices rely on the MccsSubrack device to determine their state, if the MccsSubrack responds with a state which the MccsTile doesn’t think is correct, it will go to the Fault state.

MccsSubrack

  • On: MccsSubrack devices are currently always On, but they will support both On and Off states once PDU control is implemented.

PaSD Repository

FieldStation

  • On: The FieldStation is On if all unmasked ports of the MccsFNDH and MccsSmartbox are On.

  • Standby: The FieldStation is Standby if all unmasked ports of the MccsFNDH are On and all ports of the MccsSmartbox are Off.

  • Off: The FieldStation is Off if all ports of the MccsFNDH are Off.

MccsSmartbox

  • On: A MccsSmartbox is On if any of its unmasked ports are On.

  • Standby: A MccsSmartbox is Standby if all ports are Off but its FNDH port is On.

  • Off: A MccsSmartbox is Off if its FNDH port is Off.

MccsFNDH

  • On: MccsFNDH is always On as there is no control over its upstream power supply.

Error Handling

Unknown State

A device enters the Unknown state when it cannot determine the power state of its hardware or when subservient devices do not report their power states. This state indicates uncertainty or a communication issue within the system.

Fault State

A device enters the Fault state when it detects a conflict between its expected power state and the actual power state of its hardware or subservient devices. For example, an MccsTile would enter the Fault state if it believes it is On, but the MccsSubrack it resides in reports that it is Off.

Future Considerations

  • Revising SpsStation Logic: There may be future work to redefine the On state of the SpsStation such that it is On if any tiles are On, provided all subracks are On.

  • Mixed State Handling: The frequent occurrence of Unknown states due to mixed power states between devices may lead to revisions in how these states are managed, particularly for the MccsStation and MccsController devices.