1. Networks strategy for control systems
28 Septembre 2001
Networks strategy for
control systems
Patrice Noury

2. No any single solution meets all the needs
System issues
ALSTOM address several market segments having specific needs:
Performances for control functions, dynamic time response, synchronisation
Credibility for supporting control functions across the network
Safety related functions to ensure process safety
Remote and advanced diagnostics to support scheduled maintenance
Quality and flexibility of engineering via tools
Long lasting of system components, upgrade control
Transparent access for on-demand reporting
No any single solution meets all the needs

3. Ethernet summary Availability of general purpose equipment:
Commodity item for office automation
Large support from IT world
Used in conjunction with TCP/IP
High speed and very high speed available
Limited availability of advanced features and ruggedised environment
Priority traffic class expediting features
Multicast over switch for selected branches
Industrial environment
IEC/ISO standard not reflecting latest IEEE publications,
implementations are conforming to minimum
standard address lower layers only (physical & data link)

4. Ethernet a commonly available LAN
Ethernet summary (2)
Application layer not stabilised, many initiatives are on-going:
HSE Fieldbus Foundation-ALSTOM is member of the consortium
IDA
ODVA IONA
ProfiNet
Many others such as IEC (substation)
Real time protocols exists but private based on TDMA type techniques
Cabling is still point to point with two links (star)
Cannot be considered as trusted for safety related systems- subject for future work in IEC 61508
Ethernet a commonly available LAN

5. WorldFIP summary
Genuine real time fieldbus developed for multiple qualities of service
Standardised in CENELEC/IEC
Scheduled exchanges with multiple simultaneous cycles to fit process demand
Industrial messaging
TCP/IP support
Highly robust to harsch environment with continued service
Bus type topology, suitable for cost effective cabling system
Trusted component suitable for safety related system up to SIL3 (according to IEC 61508)

6. WorldFIP use all the available bandwidth:
WorldFIP summary (2)
Limited availability, but components can be fully developed based on the standard.
Due to its inherent flexibility, traffic should be organised, tools are available.
WorldFIP use all the available bandwidth:
Traffic is scheduled on a per variable basis, no need for any time allowance
Variable addresses are not related to device address, no need for extra time slot, or agreed time slot
Global efficiency above 80 %
Industrial reliability of implementation, lifetime over 15 y
WorldFIP a high quality trusted fieldbus

7. Systems are a collection of functions:
Class of functions
Systems are a collection of functions:
Control, high speed data acquisition, synchronisation
Monitoring, supervision
Event logging, data historian
Configuration offline or online incl. on demand processing
Maintenance online
Safety related function
Video
Each system instance has its own mix leading to a communication architecture hierarchy

8. Function requirements
Real time
type
scope
integrity
Security
Pro vable
Control, data acquisition
Schedule
X cycles
Short
known
Local field
Yes
med No
yes
Data flow confined
Supervision
On changes
Long
Local plant
N/Y
rmte
Open access
Events logs
Event driven time tagged
traceabilty
Configuration, programming
On request
seg
Y/N
Download
Servlet
Maintenance
On request during operation
seg, uknwn
World
wide Y
Transparent access, applets
Safety control
Local
funct
YES
high
Resilient
tolerant
Audio/Video monitoring
uknwn N

9. Control architecture requires a defined hierarchy and scoping:
Approach
Compromise is necessary as only one communication architecture will be implemented
Other exchanges have to use the remaining bandwidth of the chosen networks
Control architecture requires a defined hierarchy and scoping:
Sampling rates are determined by the physics and synchronised
Real time requirements are coming loose for upper levels of process optimisation
Real time communication should also support on demand communication

10. Generic architecture Inter-partners Plant management Ethernet
ATM, SDH...
Plant management
Ethernet
coordination
Gateway
Router
IP addressing
Real time
Real time
Real time
WorldFIP
Available protocols
hart, CS103, Modbus

11. Architecture features
Transparent access from top to bottom
IP address for each device allow a direct access to target equipment without proxies
Web technology for browsing device capabilities and health
Scheduled traffic MPS, multi-period sampling
Control exchanges are done according to process requirements
No over-sampling
Redundancy, availability
Support of device and network redundancy
confidence assessment can be done without additional feature for high integrity functions (IEC 61508)
Testability and validation
Ability to demonstrate conformance to spec.

12. Train Control Architecture

13. Train control architecture
Features
mfg cost savings
flexibility for commissioning and development
reliability and maintainability improvement
weight saving
integration of safety related functions (SIL 3)
Functions
breaking, traction control
information display and monitoring
passenger comfort and information (incl. Audio)

14. Power plant control architecture
Intranet
Controcad
Centralog Simulation
Centralog
Optiplant +
Controtest
Controbloc
Acquisition
1ms cycle
Fieldbus
subscribers
Cycle
base
50ms
P320
Ethernet
WorldFIP

15. Power plant control architecture
Distributed intelligence for easier engineering
Flexible redundancy
management of evolution (non regression)
High integrity level
environment
cyclic processing of control with no interrupt
known load
no influence of messaging over cyclic processing
integration of safety functions
certified by Bureau Veritas for flame burner management (as regards IEC 61508…)

16. conclusions
No single solution for conflicting requirements, but Ethernet has wider acceptance for LAN
Importance of IP rather than Ethernet for transparent access and integration in IT system,
What application layer over TCP/IP?
Unrivalled added value of WorldFIP for data sampling, control function and time sync.,
Growing importance of system integrity and need for trusted communication, justifying WorldFIP choice.
To benefit of both thanks to com architecture