Judging Criteria

1. Supports performers through best practices.

The system uses dynamic, rule-based feedback presented in place within an easily interpreted visual context to reduce or eliminate many kinds of errors, thus preventing relatively unskilled or inexperienced beginners from using it incorrectly but allowing flexible performance by more experienced and advanced users. Support is provided for widely differing working styles and programming approaches, allowing conformance to various national, company, and individual standards of practice and performance.

2. Establishes or aids in establishing goals.

A variety of techniques—embedded prompts, cascading tool-tips, dynamic feedback on affordances and constraints, representational display, stored rules, visual navigation scheme—clearly communicate to the user what can and cannot be done at any point in the process.

3. Minimizes terminology translation or interpretation.

The user’s cognitive load is minimized by matching the actual working context with appropriate graphical representation of real-world equipment features without falling into the trap of excess literalism or misleading metaphors. Casual errors—such as accidentally selecting the wrong module to examine or improperly inserting a module—are reduced or eliminated through strong visual feedback in context. Users are not forced into unnatural work patterns by rigid step-by-step operation nor are they taken out of their mental working model by intrusive message dialogs. The established jargon and terminology of the PLC programming field and user community is used throughout along with explanatory tips and prompts wherever appropriate.

4. Provides access to supporting and learning resources.

Explanatory and tutorial material is provided in context and in place through a variety of novel visual feedback techniques. Embedded prompts provide hints and tips where needed within visual elements of the user interface. Cascading tool tips give users access to successive levels of detail and explanation along with contextual links into the full help system. Error conditions are communicated through highlighting in place, with further explanation available through tool tips and/or animated roll-down messages that provide information to the user as needed without unduly interrupting either the visual context or the user’s mental processes.

5. Focuses on tasks, processes, and the natural flow of work.

The entire user interface was based directly on a comprehensive model of user tasks. Because of the complexity and great variability in the tasks of PLC programming, the system has been designed for maximum flexibility without sacrificing either clear and simple navigation or reduction in user errors. The layout, operation, and navigation reflect the mental models and work practices of professional PLC programmers. The system allows performers to employ whatever sequence of workflow or style of programming is most natural to them consistent with their training, background, and problem-solving style. For example, hardware configuration can be completed with full support for correct configuration independent of the order of individual subtasks.

Novel techniques are used to provide feedback about permitted or prohibited actions and about error conditions within the working context so as not to unduly interrupt the work flow or the user’s thought processes. Like the hardware configuration view, each interaction context contains all the needed tools and materials for completion of a well-defined part of the PLC programmer’s work. Navigation between interaction contexts is accomplished easily and quickly through the combination of the project explorer and the view tabs within each set. Within hardware configuration, visual feedback in context is used to guide and constrain the user to correct configurations based on the software's built-in knowledge of hardware modules and configuration rules. Users are almost completely prevented from constructing impossible or illogical hardware configurations.

6. Stretches the PCD/EPSS paradigm.

The enormous variability and cognitive and operational complexity of automation programming represents an expanded challenge for performance-support and performance-centered design concepts, requiring techniques that go beyond many of the more traditional and established approaches to user interface design.

The Step 7 Lite user interface design is based on a new paradigm for complex user interfaces that can be described as instructive interaction. With instructive interaction, performers learn how to use a system through the process of using it, rather than through separate instruction, manuals, or tutorials. The goal of instructive interaction is to make complex systems self-teaching.

Instructive interaction integrates a diverse body of established and innovative techniques to render novel user interfaces immediately understandable and usable. With instructive interaction, guidance and feedback are intrinsic to the user interface itself and are provided in context. Thus, for example, PLC programmers using Step 7 Lite are not told in advanced precisely how to set up a configuration of hardware modules, they are not stepped through a fixed or inflexible sequence, and they are not informed after the fact by error messages should they attempt an incorrect or illogical arrangement. Instead, the moment they attempt to add a hardware module to a configuration, the appearance of the system changes to convey where that module may or may not be placed. Likewise, they need not be told that the tabular and graphic views are synchronized and connected in a certain way; any attempt to operate on either immediately reveals the relationship and is reinforced with visual cues that show exactly which element in one view corresponds to which in the other. The success and novelty of this approach rests not so much in any one technique but in the way in which all the details fit together and reflect an underlying insight into the detailed nature of the supported tasks.

By basing the design directly on a comprehensive and detailed task model, the user interface is able to offer users both highly structured guidance and complete performance flexibility along with improved performance efficiency. This approach also allows a single interface to be equally well suited to the needs of the rank novice and to those of the more experienced or expert user. Through guidance that is both intrinsic and in context, subtle help and reinforcement are provided for the beginner without getting in the way of those with more advanced needs and skills. Everything the user of any skill level needs in terms of tools and materials as well as guidance and feedback is provided in one readily comprehended context.