ITER Control System Technology Study

1
ITER Control System Technology Study
Klemen Žagar klemen.zagar_at_cosylab.com
2
Overview

• About ITER
• ITER Control and Data Acquisition System (CODAC)
  architecture
• Communication technologies for the Plant
  Operation Network
• Use cases/requirements
• Performance benchmark

3
A Note!

• Information about ITER and CODAC architecture
  presented here-in is a summary of ITER
  Organizations presentations
• Cosylab prepared studies on communication
  technologies for ITER

4
About ITER (International Thermonuclear
Experimental Reactor)
5
About ITER
29m
28m
6
CODAC Architecture
7
Plant Operation Network (PON)

• Command Invocation
• Data Streaming
• Event Handling
• Monitoring
• Bulk Data Transfer
• PON self-diagnostics
• Diagnosing problems in the PON
• Monitoring the load of the PON network
• Process Control
• Reacting on events in the control system by
  issuing commands or transmitting other events
• Alarm Handling
• Transmission of notification of anomalous
  behavior
• Management of currently active alarm states

8
Prototype and Benchmarking

• We have measured latency and throughput in a
  controlled test environment
• Allows side-by-side comparison
• Also, hands-on experience is more comparable
• Latency test
• Where a central service is involved (OmniNotify,
  IceStorm or EPICS/CA)
• Send a message (to the central service)
• Upon receipt on the sender node, measure
  difference between send and receive times
• Without a central service (OmniORB, ICE, RTI
  DDS)
• Round-trip test
• Send a message (to the receiving node)
• Respond
• Upon receipt of the response, measure the
  difference
• Throughput test
• Send messages as fast as possible
• Measure differences between receive times
• Statistical analysis to obtain average, jitter,
  minimum, 95th percentile, etc.

9
Applicability to Use Cases
CHANNEL ACCESS omniORB CORBA RTI DDS ZeroC ICE
Command invocation 4/2 5 /5 4/3 5/5
Event handling 4/3 4/4 5/4 4/5
Monitoring 5/5 (EPICS) 5/5 (TANGO) 5/3 5/3
Bulk data transfer 5/3 4/4 5/4 4/4
Diagnostics 5 4 5 3
Process control 5 (EPICS) 5 (TANGO) 4 3
Alarm handling 5 (EPICS) 5 (TANGO) 3 3

• First number performance
• Second number functional applicability of the
  use case

1. not applicable at all
2. applicable, but at a significant
   performance/quality cost compared to optimal
   solution custom design required
3. applicable, but at some performance/quality cost
   compared to optimal solution custom design
   required
4. applicable, but at some performance/quality cost
   compared to optimal solution foreseen in
   existing design
5. applicable, and close to optimal solution use
   case foreseen in design

10
Applicability to Use Cases
CHANNEL ACCESS omniORB CORBA RTI DDS ZeroC ICE
Command invocation 4/2 5 /5 4/3 5/5
Event handling 4/3 4/4 5/4 4/5
Monitoring 5/5 (EPICS) 5/5 (TANGO) 5/3 5/3
Bulk data transfer 5/3 4/4 5/4 4/4
Diagnostics 5 4 5 3
Process control 5 (EPICS) 5 (TANGO) 4 3
Alarm handling 5 (EPICS) 5 (TANGO) 3 3

• First number performance
• Second number functional applicability of the
  use case

1. not applicable at all
2. applicable, but at a significant
   performance/quality cost compared to optimal
   solution custom design required
3. applicable, but at some performance/quality cost
   compared to optimal solution custom design
   required
4. applicable, but at some performance/quality cost
   compared to optimal solution foreseen in
   existing design
5. applicable, and close to optimal solution use
   case foreseen in design

11
PON Latency (small payloads)
12
PON Latency (small payloads)

• Ranking
• OmniORB (one way invocations)
• ICE (one way invocations)
• RTI DDS (not tuned for latency)
• EPICS
• OmniNotify
• ICE storm

13
PON Throughput
14
PON Throughput

• Ranking
• RTI DDS
• OmniORB (one way invocations)
• ICE (one way invocations)
• EPICS
• ICE storm
• OmniNotify

15
PON Scalability

• RTI DDS efficiently leverages IP multicasting
• (source RTI)

• With technologies that do not use IP
  multicasting/broadcasting, per-subscriber
  throughput is inversely proportional to the
  number of subscribers!
• (source RTI)

16
EPICS

• Ultimately, ITER Organization has chosen EPICS
• Very good performance.
• Easiest to work with.
• Very robust.
• Full-blown control system infrastructure (not
  just middleware).
• Likely to be around for a while (widely used by
  many labs).
• Where EPICS could improve?
• Use IP multicasting for monitors.
• A remote procedure call layer (e.g., abuse
  waveforms to transmit data serialized with with
  Google Protocol Buffers, or use PVData in
  EPICSv4).

17

• Thank You for Your Attention