AC 800M High Integrity

The AC 800M HI controllers, PM857, PM863 and PM867 offers a certified TÜV control environment for process safety applications in both integrated and stand-alone environments. The AC 800M HI controller, in combination with a diverse co-processor, SM812, performs diagnostics and monitoring of application execution and I/O scanning. The HI controllers offer flexibility of network design as they can be used for integrated but separate safety operations or for fully integrated applications where safety and business critical process control are combined in one controller without sacrificing safety integrity.

For embedded safety and control applications, all functions/types in standard libraries usable in SIL classified application are marked SIL2, SIL2 Restricted, SIL3 or SIL3 restricted. Embedded safety measures prevent inadvertant degradation of safety applications. SIL selection activates the relevant restrictions and limitations, such as only SIL marked elements to be used in SIL applications.

In SIL rated applications,it is possible to choose between three IEC 61131-3 languages, Function Block Diagram, Structured Text, and Sequential Function Chart (only SIL1-2). For non-SIL applications, all five IEC 61131-3 languages are available for use.

AC 800M Engineering

800xA's object oriented engineering environment with SIL-compliant function libraries efficiently supports the entire safety lifecycle. The 800xA engineering environment includes safeguards against non-SIL compliant configurations. Once identified as a safety application, the engineering system will automatically limit user configuration choices and will prevent download if SIL requirements are not met.

A series of safety measures are implemented both for the downloading process and runtime environment. These measures form an important part of the firewall mechanism for Embedded Control and Safety. CRC protection on different levels, double code generation with comparison and compiler with revalidation are just a few examples of the AC 800M HI embedded firewall mechanisms.

Specifically, System 800xA provides the following additional measures for safety system engineering:

• IEC61131-3 language usage
• Access control and override (force) control
• Application change report
• Application libraries and solutions

Programming Language

Function Block Diagram (allowed for Non-SIL and SIL1-3)

Function Block is a graphical language for depicting signal and adta flows by means of library-stored software elements and interconnecting signals. Function block programs are easy to develop and, thanks to the resulting graphical diagrams, also easy to read.

Structured Text (allowed for Non-SIL and SIL1-3)

Structured text (ST) is a high-level programming language. It has a comprehensive range of constructs for assignments, function calls, expressions, conditional statements, iterations, etc. ST lends itself well to writing advanced, compact - yet easily understandable - programs thanks to its logical and structured layout. For SIL appications there are some restrictions according to IEC61131-3 (Loops, parallell execution and Return is not allowed).

Sequential Function Chart (allowed for Non-SIL and SIL1-2)

Sequential function chart (SFC) is a graphical language for depicting the sequential behavior of a control system. It is used for defining time- and event-driven control sequences. A sequence is shown in flow-chart form, using steps, transitions and selection nodes. The language is amply suited to the handling of control tasks which are sequential in nature, i.e. consisting of a number of distinct steps, each requiring a number of enabling inputs where the comletion of the previous step usually is one of them.

See more details in the User Manual 800xA - Safety, Safety Manual