Application-Based Controller Redundancy (ACR) from WAGO

Crew-free ships – not the romantic notion of a sailor? Initiatives for autonomous ships are driving this development. However, there’s a long way to go in getting engine rooms, which can currently operate for up to 24 hours straight without direct intervention, to a completely autonomous ship that should be able to run for up to six weeks at sea without human intervention. WAGO’s redundancy concept for controllers is shortening this path and offers a solution for compensating for faults occurring in the automation systems while ensuring the continued operation of technical systems.

The greatest challenge on the way to increasing ship automation is still establishing onboard systems that are so reliable that outside intervention is unnecessary. This can be achieved by using a larger proportion of standardized components on board, while maintaining high availability of security relevant systems through redundancy. In order to guarantee the automation systems' reliability, the voltage supply and the communication medium (e.g., ETHERNET), in addition to the PLC, must satisfy the technical system’s uptime requirements. WAGO provides a simple and economic solution for its maritime customers that uses an application-based redundancy concept for controllers.

WAGO’s e!COCKPIT engineering software tool is used as the programming environment for the controllers. The multi-node programming environment can easily transmit the PLC program to both PLCs. For the application-based controller redundancy to be used, a software library with the necessary synchronization functions must be linked to the master PLC. The library offers the possibility of redundantly linking subnodes using a dual LAN. The subnodes, also known as smart couplers, do not have to be programmed; they can be simply booted from an SD card and then configured using an integrated webserver. Both analog and digital input/output modules are detected automatically by the smart coupler; process mapping is likewise automatically made available to the higher-level master PLCs. The master PLCs can communicate with higher-level SCADA systems via the Modbus-TCP protocol. The redundant connection is performed over two separate networks.

The solution's design corresponds to an SPOF-tolerant system (single point of failure), which means that any occurring fault – like a voltage supply failure, a poor LAN connection, switches, or controller – can always be compensated for. Doubling the ETHERNET topology and the redundant message transmissions enable instantaneous switching during a network fault. Typical switching times after a PLC failure are within DNV GL requirements when used in typical alarm and monitoring systems.

Text: Norman Südekum
Photo: WAGO

Twice the Reliability on the Seven Seas

The WAGO redundancy concept for controllers offers customers, particularly those in the offshore sector, significant advantages due to the use of intrinsically safe modules and the transmission of the most important secondary variables that adheres the HART protocol.

What can WAGO's application-based controller redundancy (ACR) do?

  • Increase availability (lengthen service life, reduce fault effects)
  • Collect and bundle data
  • Generate media redundancy both via ring and doubled network infrastructure
  • Modular and scalable

Additional advantages:

  • Easy commissioning of the entire system with WAGO’s standard hardware
  • Simple/slow control loops can be mapped
  • Lower switchover times (in accordance with classification society requirements)
  • Intrinsically safe modules are available
  • Transmission of the most important secondary variables using the HART protocol

The standard components used by WAGO guarantee high availability, low expenses and substantial cost advantages.

Norman Südekum, Market Management Process & Marine

Openness in the Network Topology

Increase availability in central ship alarm systems with WAGO's ACR.

Application-Based Controller Redundancy

WAGO provides a sample project for 30 days and the necessary library. Register here to download the redundancy framework and test ACR free of charge for 30 days.

Library Controller Redundancy Master; Single license; Online activation (2759-245/211-1000)

This Link will take you to our eShop to purchase the license for the production system.