LEB Workshop ‘98, Rome, Detector

Control System, H.J.Burckhart, 1

DCS Detector Control SystemDetector Control SystemH.J Burckhart, CERNH.J Burckhart, CERN

Motivation and Scope Detector and Requirements Architecture and Functions Front End System Practical Work Summary

LEB Workshop ‘98, Rome, Detector

Control System, H.J.Burckhart, 2

DCS MotivationMotivation

Detector is too complex to be controlled manually Each expert covers only a (small) part of the

experiment Expertise gets lost with time It is important to detect problems early Possibility is needed to bring the detector

automatically in a safe state

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DCS Motivation (…)Motivation (…)

… and also...

Find the original cause of the problem Give “forecast” of problems about to come up

…and perhaps in the end…

Correct problems automatically

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DCS ScopeScope

Operate the experiment in a homogenous way Control all subdetectors

including magnets, cryogenics, etc.

Interface to infrastructure and services electricity distribution, cooling, ventilation,cryogenics

Interact with the LHC machine luminosity, background, radiation, beam dump, injection inhibit, etc.

Cover the full range of operation shift operator <--> expert interaction

Take care of the operational safety of detector

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DCS Scope (...)Scope (...)

Present the global safety status to the operator Provide a good connection to DAQ, but keep

operational independence Promote standardization amongst subdetectors

resources, maintenance

Enable evolution from a (small) stand-alone system to the integrated operation in the final experiment

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DCS Scope (...)Scope (...)

DCS is not responsible for: safety of personal ultimate safety of equipment

hardwired interlocks, PLC

DCS is not concerned with physics events: monitoring of physics data quality control of physics data flow

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DCS Scope (...)Scope (...)

Important rules:

DCS is the mandatory tool for all actions of the operator on the detector

DCS is mandatory for the presentation of all error messages and alarms to the operator

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DCS Detector OrganizationDetector Organization

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DCS Detector Time ScaleDetector Time Scale

R&D now “Module 0” test now mass production 1999 (pre-) assembly 2000 calibration 2000 installation 2003 physics data taking 2005

=> each phase has controls needs

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DCS Selected RequirementsSelected Requirements

Only selected points which are special as compared to industrial controls

are discussed here:

capability for stand-alone controls of sub-systems easy integration of sub-systems in the overall system robust, minimal operation e.g. also during power cut flexible (control procedures change) basic operation independent of DAQ system good connection to DAQ (information exchange, data

base, etc.)

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DCS Selected Requirements (…)Selected Requirements (…)

Critical functions must be automated, no operator intervention needed

intuitive user interface (no trained operators) operation of front end electronics in magnetic field radiation environment low power dissipation

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DCS ArchitectureArchitecture

Hierarchically organized in layers (like the detector):

Supervisor GUI, alarms, logging, etc.

Local Control Station (LCS) autonomous supervision of part of experiment

Programmable front end system PLC, Fieldbus nodes

Sensors and actuators temperature, valve, etc.

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DCS ArchitectureArchitecture

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DCS Architecture (…)Architecture (…)

Remarks: classification into ‘sub-detectors’ and ‘external systems’ onto which layer to map a of piece of hardware depends on

complexity, functions needed, etc. information flow mainly up/down, not horizontally standardised LCS is the boundary between DCS and

subdetectors propose also a standardised solution for front end system

(Temp. Measurements, power supplies, etc.) standardise gateways for information exchange with

“external system” (LHC machine, cooling/ventilation, electricity distribution, etc.)

interaction with safety system only “one way”

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DCS FunctionsFunctions

On-line status display alarm handling history plots data logging command logging incident logging

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DCS Functions (...)Functions (...)

operator or event driven execution of expert-defined procedures

state transition, calibration, shut down, etc.

operator assistance help facility, suggestion for actions, problem analysis

remote (restricted) access via network

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DCS Functional ArchitectureFunctional Architecture

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DCS Front End SystemFront End System

Requirements: Radiation Tolerance

selection of COTS over-design performance, allow for degradation operate at lower values than specified install at protected and accessible places replace after n years

Operation in magnetic field no coils, chokes, transformers, DC/DC remote power

Distributed cluster of I/O points

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DCS Front End System (…)Front End System (…)

Solutions: Fieldbus:

“simple” cable bus connecting “intelligent” nodes using a well defined protocol

wide range (sensor bus, device bus, LAN) many industrial standards many industrial products (chip<->devices, drivers<->

network management) characteristics: robustness, bandwidth, topology, length,

openness, determinism, bus mastership, error handling, redundancy

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DCS Front End System (…)Front End System (…)

Programmable Logic Controller (PLC) simple program structure (one loop, interrupts) robust deterministic dedicated programming environment connection via LAN and/or Fieldbus

proprietary flexibility limited

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DCS Front End System (…)Front End System (…)

Fieldbus and PLC suited for front end system distributed I/O concentrator remote diagnostics (no access) local low level control tasks local data treatment and reduction

Standardization across LHC experiments CERN selected Fieldbuses: CAN, Fip, Profibus Fieldbus nodes

general purpose (ADC, digital I/O, …) purpose built (chamber controls, rack controls, …)

Fieldbus devices (HT systems, crates, … ) PLC (magnets, gas, cryogenics, … )

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DCS Practical WorkPractical Work

CERN Joint Controls Project (JCOP): Collection of requirements high level architecture investigation and evaluation of commercial control

system generic controls of subsystem and devices ( HV,

racks, gas, … ) Fieldbus HW and SW

CAN CanOpen LMB

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DCS SummarySummary

Hierarchical controls architecture Commercial solutions (HW, SW) Fieldbus and PLC very suited for lowest

level Standardisation across LHC experiments

(and machine !)