INTRODUCTION
The Mark* VIe control system is a flexible platform used in multiple applications. It features
high-speed, networked input/output (I/O) for simplex, dual, and triple redundant systems.
Industry-standard Ethernet communications are used for I/O, controllers, and supervisory
interface to operator and maintenance stations, as well as third-party systems. The
ControlST* software suite, which contains the ToolboxST* toolset, is used with Mark VIe
controls and related systems for programming, configuration, trending, and analyzing
diagnostics. It provides quality, time-coherent data in the controllers and at the plant level for
effectively managing control system equipment. The Mark VIeS Safety control is a stand-alone
safety control system for safety-critical applications that conform to IEC®-61508. It also uses
the ControlST software suite to simplify maintenance, but retains a unique set of certified
hardware and software blocks. The ToolboxST application provides a means to lock or unlock
the Mark VIeS for configuration and safety instrumented function (SIF) programming.
SYSTEM OVERVIEW
A single-board controller is the heart of the system. The controller includes
the main processor and redundant Ethernet drivers to communicate with
networked I/O, and additional Ethernet drivers for the control network. A
real-time, multi-tasking operating system is used for the main processor
and I/O modules. Control software is provided in a configurable control
block language and stored in non-volatile memory. It is similar to IEEE® 854
32-bit floating-point format, and Sequential Function Charts (SFC) are also
available for complex sequencing.
The I/O network (IONet) is a dedicated, full-duplex, point-to-point
protocol. It provides a deterministic, high-speed 100 MB communications
network that is suitable for local or distributed I/O devices, and provides
communication between the main controllers(s) and networked I/O
modules. Online controllers continuously read input data directly
from the IONet, which is available in single, dual, and triple redundant
configurations. Both copper and fiber interfaces are supported.
The Mark VIe I/O modules consist of three basic parts: the terminal board,
the terminal block, and an I/O pack. Barrier or box-type terminal blocks are
mounted on a terminal board, which mounts on a DIN rail or base in the
control cabinet. The I/O pack contains two Ethernet ports, a power supply,
a local processor, and a data acquisition board. I/O capability grows as I/O
packs are added to the control system, enabling use in a simplex, dual, or
triple redundant configuration. Some process sub-systems require even
more throughput; therefore, the local processors in each I/O pack run
algorithms at higher rates as required for the application.
REDUNDANCY
Every application has different requirements for redundancy depending on
the criticality of the process. The Mark VIe control system provides a wide
range of redundancy options for local and remote distribution.
Dual redundant systems transmit inputs from single or redundant input
packs on dual IONets to dual Mark VIe controllers. Controllers then run
application software and transmit outputs to output packs. Three output
I/O packs may be provided to vote output signals for mission-critical field
devices. Dual redundant systems may be configured for single, dual, and
triple redundant sensors.
Triple redundant systems protect against soft or partial device failures. A
failed component is outvoted with a 2-out-of-3 logical selection (vote) or
a median value selection. Control software in all three Mark VIe controllers
runs on the voted value of the signal while diagnostics identify the failed
device. These sophisticated diagnostics reduce the mean-time-to-repair
(MTTR) while the online repair capability increases the mean-timebetween-forced-outages (MTBFO). Field sensors for these systems may
be single, dual, or triple.
I/O INTERFACE
One or multiple I/O packs are mounted on each module to digitize the
sensor signal, run algorithms, and communicate with a separate controller
containing the main processor. I/O packs have a local processor board
that runs a real-time operating system and a data acquisition board that
is unique to the specific I/O application. Local processors run algorithms
at faster speeds than the overall control system, such as the regulation of
servo valves performed within a servo module.
Each I/O processor has a local temperature sensor accurate to ±2°C (±3.6
°F). Detection of an excessive temperature generates a diagnostic alarm
and the logic is available in the database (signal space) to facilitate control
action or unique process alarm messages. The temperature is continuously
available in the database. I/O module features include:
• Dual 100 MB Ethernet ports
• 100 MB full-duplex ports
• Online repair per I/O pack