2D or not 2D: that is the question

Simple 2D is perfectly adequate for many kinds of technical drawings such as schematics, layouts and circuits. The current crop of 2D drawing tools are easy-to-use and smart.

A large number of traditional CAD programs are steadily becoming 3D modelling programs. However, there are many areas of design and technical drawing remaining where 2D representation is still appropriate.

Today’s users expect drawing tools to have graphical user interfaces with point, click & drag or graphical and geometric input, pre-drawn drawing components and intelligent drawing behaviour. Also, many of today’s users are focused on end-product drawings and may not even have any CAD experience.

Drawing electrical schematic diagrams is one of the easiest possible tasks for CAD. Such drawings are inherently 2D, and there are no considerations of scale for the objects being drawn. Making drawings involves placing pre-drawn symbols and connecting them with lines. Built-in symbol or block facilities are ideal tools for this job. Unfortunately, traditional CAD products, and particularly AutoCAD, have failed to provide satisfactory tools for storing and accessing symbol libraries.

Below, I explore the options and facilities available in Autodesk Actrix, Microsoft Visio and Intergraph SmartSketch with emphasis on using these programs for electrical drawing work.

There are other, more costly solutions specifically for electrical and electronic design work. But I have not considered software that includes extensive automated facilities and design support tools, automated parts list and wiring documentation.

Microsoft Visio 2000 Technical

(www.microsoft.com/office/visio)

Visio is the 2D drawing market leader and the ‘industry standard’ for office diagramming work throughout the corporate world. Its strength lies in a combination of key features – ‘drag & drop’ pre-drawn symbols, automated symbol interconnection lines, and its ‘smart shapes’ technology, which enables intelligent automatic variation of the symbols to suit the context and the user’s dragging of their size or shape. Microsoft acquired Visio last year. A new release is expected in July this year.

Visio is exceptionally good for the types of drawing that office people want to do, but lacks some of the key facilities that would make it a complete 2D CAD system. It was squarely aimed at diagramming, where scale and dimensioning are not issues.Visio’s major feature is its ‘smart shapes’, so-called because practically any aspect of the behaviour of these pre-drawn symbols – orientation, connectivity, associativity, labelling, colour, inter-relationship with other symbols – can be programmed.

This is especially powerful for designing factory and office layouts but less so for diagramming circuits. Other powerful features include connection points which ensure that interconnection lines automatically snap onto sensible parts of the symbol, and dynamic connectors that stay connected and even re-route themselves if a symbol is relocated on a drawing.

For electrical and electronic diagramming, Visio supplies ready-made Shape Templates (Visio terminology for symbol libraries), and includes both American JIS and IEC standard symbols. You can create additional symbols yourself and Visio is highly programmable, but training is required to master its programming system.

Visio consumes considerable PC resources, and its data file format is not easily transferable to any other system although Visio does provide a DXF export facility.The latest release of Visio has seen the Technical version disappear. All the components that differentiate technical will be included in the Professional version and the price has increased too.

Autodesk Actrix 2000

(www3.autodesk.com)

In Actrix and Visio we see two very similar products produced by companies that dominate two different markets. Microsoft looks at 2D drawing from the viewpoint of the admin office, while Autodesk sees it from the perspective of the engineering office.

Furthermore, as an Autodesk product, Actrix incorporates more thorough facilities for interaction with AutoCAD DWG data.

Actrix scores well for convenience in diagram work because you can drag and drop symbols from a library palette, symbols have built-in connection points for wiring lines, and, once connected, will maintain the connections with automatic orthogonal re-routing if you re-position the symbols. Also like Visio, it provides very well for annotating symbols semi-automatically.

Actrix comes with a large number of ready-made symbol libraries for electrical and electronic work, including both IEC/ISO and American JIS standards. Actrix provides the tools for creating your own symbols and applying smart behaviour to them, but this is not a trivial task. You can also convert symbol blocks intended for AutoCAD into Actrix symbols, which would perhaps be the easiest course of action. Actrix can convert shape data from Visio, retaining all built-in intelligence, but only if the Visio product is also installed on the same PC.

Intergraph SmartSketch

(www.intergraph.com/imagine)

Intergraph’s SmartSketch is a top class general 2D drafting and design tool that could also be used for office diagramming much more easily than conventional CAD programs. It comes from an engineering-based starting point rather than the office-based starting point of Visio and Actrix.

The core of SmartSketch is its ‘smart’ cursor and ‘smart’ object-snap methods. Instead of the diversions to set snap modes and the need to set up temporary guide-lines, the cursor continually shows fleeting geometrical relationships to nearby or distant objects and relevant snap possibilities as you drag a new line-end around seeking the correct end-point for it.

The SmartSketch screen display is not greatly different to the others discussed here but its strength lies in its mode of operation.

You can group lines to make objects and make them retain geometric relationships to others, and to pivot or slide and behave in a proper mechanical manner. This makes it easy to animate mechanisms and check for clearances, although only in 2D.

In its current release SmartSketch includes drag-&-drop symbols with programmed behaviour rather like the core features of Visio and Actrix. It also has the automated interconnection system, where connection lines auto-adjust if you rearrange the associated symbols. SmartSketch really does merge full general CAD functionality with the ‘smart symbol’ drag-&-drop idea.

SmartSketch can also work with AutoCAD DWG data. It works on DWG (AutoCAD native file format) and DGN (Microstation native file format) data files without translation. You can work on a drawing comprising data from AutoCAD and MicroStation as well as data created within itself. It also provides exceptional drawing aids for any type of drafting work. Its system of automatic object snaps and alignment with existing geometry features makes any sort of 2D drawing work very fast and accurate.

However, for electrical diagramming use outside America, SmartSketch is a disappointment. The symbol libraries provided are entirely American standards only. They provide ‘metric’ versions, but they are actually the same JIC symbols in metric dimensions. So far there appears to be no source of alternative IEC/ISO libraries, although Intergraph claims that this problem is being addressed.

So which is it to be?

Visio and Actrix can interchange data with AutoCAD DWG files, Actrix perhaps more completely. Symbol libraries provided with Visio are extensive and international. SmartSketch can also work the two most common CAD file formats and has an intelligent drawing interface, but is lacking in pre-drawn symbol content.

These three products provide truly useful, powerful and easy-to-use new technology for 2D drafting. After using any of these drawing tools, it’s a real ‘drag’ going back to old-fashioned CAD.