The Mark VIe control system emerges as a sophisticated solution engineered to meet the rigorous demands of modern automation across a diverse spectrum of applications, from power generation to complex manufacturing processes. This integrated platform distinguishes itself through its advanced architecture, which seamlessly blends high-speed deterministic networking with comprehensive redundancy options and a unified software environment.
At the heart of the Mark VIe system lies a powerful single-board controller. This unit integrates the main processing unit with redundant Ethernet drivers specifically designed for managing network input/output (I/O) communications. Additional dedicated Ethernet interfaces are incorporated to handle control network traffic, ensuring segregated and prioritized data flow. The controller operates on a real-time, multi-tasking operating system, guaranteeing deterministic performance for time-sensitive control loops. Application logic is executed using a configurable block-based programming language, stored in non-volatile memory to prevent loss during power cycles. This language, akin to the IEEE 854 32-bit floating-point format, provides engineers with a powerful and familiar environment for developing complex control strategies. Furthermore, Sequential Function Charts (SFC) are available for orchestrating intricate operational sequences, enhancing the system's capability to manage sophisticated multi-stage processes.
A pivotal element of the architecture is the I/O Network, or IONet. This is a dedicated, full-duplex, point-to-point protocol that establishes a deterministic, high-speed 100 MB communications infrastructure. The IONet is engineered to support both localized and distributed I/O devices, serving as the critical data highway between the main controller(s) and the various networked I/O modules. Its deterministic nature ensures that data packets are delivered within a guaranteed timeframe, which is essential for precise control applications. The network supports single, dual, and triple redundant configurations, and offers both copper and fiber optic interfaces to cater to different installation requirements, such as immunity to electromagnetic interference in harsh plant environments.
The physical I/O subsystem is structured around modular I/O packs. Each module is composed of three primary elements: a terminal board, a terminal block, and the I/O pack itself. Barrier or box-type terminal blocks are mounted onto the terminal board, which is subsequently secured to a DIN rail or a baseplate within the control cabinet. The I/O pack is the intelligent component, housing dual Ethernet ports for connection to the IONet, a power supply, a local dedicated processor, and a data acquisition board specifically tailored for its I/O function. This modular design allows for scalable system expansion; I/O capacity is increased simply by adding more packs to the network. This flexibility enables deployments in simplex, dual, or triple modular redundant (TMR) configurations. For applications demanding exceptional speed, such as servo control, the local processor within each pack can execute specialized algorithms at rates significantly higher than the main control loop, offloading processing burden from the central controller and enhancing overall system performance.
The Mark VIe platform is renowned for its extensive and configurable redundancy capabilities, which are tailored to the criticality of the process being controlled. Redundancy philosophies can be applied to sensors, networks, controllers, and output modules, providing a defense-in-depth approach to maximizing availability and mitigating single points of failure.
Dual redundant systems are a common configuration for high-availability applications. In this setup, input signals from sensors are read by input packs (which can themselves be single or redundant) and transmitted over dual, independent IONets to a pair of Mark VIe controllers. These controllers run identical application software in lockstep. Outputs from the controllers are then sent to output packs. For the most critical final control elements, a triple voting output scheme can be implemented, where three separate output I/O packs receive the command signals. A hardware or software-based voter selects the correct output based on a majority vote (2-out-of-3), ensuring that a failure in one output channel does not cause a spurious action in the field device. This architecture can accommodate single, dual, or triple redundant sensor inputs.
For the utmost criticality, a triple modular redundant (TMR) system is deployed. This configuration is designed to tolerate a failure in any single component without disrupting the process. Three independent controllers run in parallel, receiving input data from triple-redundant sensors via three separate IONets. The system continuously performs a vote (either a 2-out-of-3 selection or a median value selection) on all critical input signals. Each controller executes its logic based on this voted, or "correct," value. Sophisticated diagnostics continuously monitor all three channels, quickly identifying and alarming upon a device failure. This capability dramatically reduces the Mean Time To Repair (MTTR) by instantly pinpointing the faulty component. Furthermore, the system's online repair feature allows technicians to replace the failed module without taking the entire process offline, thereby significantly increasing the Mean Time Between Forced Outages (MTBFO). Field sensors for these systems can be configured as single, dual, or triple, depending on the required level of integrity.
The I/O packs within the Mark VIe system are far more than simple signal converters; they are intelligent devices that contribute significantly to the system's overall capability. Each pack features a local processor board running a real-time operating system and a specialized data acquisition board. This design allows for distributed processing, enabling functions like fast PID loops or servo valve regulation to be executed locally within the module at very high speeds, independent of the main controller's scan time.
A key feature of these modules is an integrated temperature sensor with an accuracy of ±2°C. This sensor continuously monitors the operating temperature of the I/O pack. If an excessive temperature is detected, it generates a diagnostic alarm. The temperature value and alarm status are made available in the control system's database (signal space), allowing control logic to take preemptive actions, such as initiating a controlled shutdown or alerting operators with a custom alarm message, thus preventing hardware damage.
Standard features across I/O modules include dual 100 MB full-duplex Ethernet ports for robust network connectivity, comprehensive support for online repair and replacement, and automatic reconfiguration upon module replacement. Accuracy specifications are guaranteed over the entire operating temperature range. Status is indicated via LEDs for power, network activity, and application-specific conditions. Modules are powered by a 28 V dc supply, which features internal solid-state circuit protection with a nominal 2 A trip point and a soft-start circuit to prevent inrush current issues. The negative DC supply is grounded through the metal enclosure, enhancing noise immunity and safety.
The Mark VIe system offers two primary types of terminal modules(T-Type and S-Type Modules) to accommodate different wiring and redundancy needs.
T-Type modules are designed for applications requiring high levels of signal redundancy and isolation. They typically distribute a single field input signal to three separate I/O packs for TMR systems. These modules contain two removable 24-point, barrier-type terminal blocks. Each point can accept two wires up to 3.0 mm² (#12 AWG) with 300 V insulation rating, and supports spade or ring-type lugs, as well as captive clamps for bare wires. Screw spacing is a minimum of 9.53 mm center-to-center. They are typically surface-mounted and include an integrated shield strip connected to the mounting base for improved electromagnetic compatibility (EMC).
S-Type modules provide a more compact and cost-effective solution for simplex, dual, or dedicated TMR applications where signals are not fanned out. They are half the size of T-type modules and can be DIN-rail or surface mounted. They offer a single termination point per I/O signal. Fixed box-type terminals accept one 3.0 mm² wire or two 2.0 mm² (#14 AWG) wires. A version with removable terminals is also available, allowing for field replacement with alternative connection technologies like spring-clamp or insulation-displacement types. Each block includes a shield strip tied to functional ground.
Mark VIe components are designed for global deployment in a variety of environmental conditions. Core electronics, including controllers, I/O modules, and power supplies, are rated for operation from -30°C to 65°C. To ensure reliability, it is recommended that modules with more restrictive temperature ratings, such as certain fieldbus gateways (e.g., PROFIBUS Master: -20 to 55°C, FOUNDATION Fieldbus: 0 to 55°C), be installed lower in the control cabinet where temperatures are cooler. Control room equipment, like operator workstations, has a more narrow operating range of 20 to 30°C. All equipment is designed to withstand broader temperature ranges (-40 to 85°C for controllers, 0 to 30°C for workstations) during shipping and storage.
The hardware capabilities of the Mark VIe are fully unlocked by the ControlST software suite. This integrated set of tools provides a unified environment for every aspect of the control system lifecycle. At its core is the ToolboxST application, which is used for programming, configuration, real-time trending, and in-depth diagnostic analysis across all Mark VIe and Mark VIeS systems. It ensures that high-quality, time-coherent data is available both within the controllers and at the plant level, forming a solid foundation for effective asset management and operational decision-making.
For safety-critical applications requiring certification under standards like IEC 61508, the Mark VIeS Safety system is employed. This system utilizes the same familiar ControlST software suite and ToolboxST toolset for maintenance and configuration, greatly reducing operator training requirements. However, it maintains a physically and logically separate set of certified hardware and software function blocks. ToolboxST provides security features to lock or unlock the safety system for configuration and Safety Instrumented Function (SIF) programming, ensuring the integrity of the safety logic is never compromised.
The system's I/O portfolio is vast, encompassing both generic modules like discrete inputs (varying by voltage rating and isolation) and highly specialized application-specific modules. For instance, dedicated servo modules provide the ultra-fast processing required for precise closed-loop control of turbine actuators. Similarly, specialized vibration monitoring modules are available to accurately measure radial and axial shaft displacement in rotating machinery, integrating protection directly into the control system. Selection criteria for modules include not just signal type, but also required redundancy, isolation level, terminal block style, safety certification (SIL), and approvals for use in hazardous locations.
References：https://www.gevernova.com/content/dam/gepower-new/global/en_US/downloads/gas-new-site/resources/reference/GEA35311-Mark-VIe-Control-Product-Description-Brochure-DRAFT.pdf
