Part 2 - A few useful AutoCAD Drawing variables

In my last article, I discussed a number of variables that take effect over the AutoCAD application itself, this time I’m going to cover a few of the common Drawing specific variables – i.e. those settings that apply to the individual dwg files rather than globally. I’ve covered a couple of the important ones previously, so also be sure to check out the previous posts on INSUNITS and VISRETAIN.

There are numerous variables available to control all manner of settings within the AutoCAD drawing environment, those shown below are just a few examples that may be encountered during a typical charting project. Further details can be found in the AutoCAD Help documentation.

FRAME – The Frame variable turns the display of frames on and off for all external references, images, and DWF, DWFx, PDF and DGN underlays. When you insert an Image, an underlay or perform an XCLIP around an external reference, the border around that object can optionally be displayed. The Frame setting overrides the individual IMAGEFRAME, DWFFRAME, PDFFRAME, DGNFRAME and XCLIPFRAME settings and can have the following values:

0 - The frame is not visible and it is not plotted

1 - Displays the frame and allows it to be plotted

2 - Displays the frame but keeps it from being plotted

3 - The individual setting varies for all underlays in the current drawing

(i.e. external references, images, and DWF, DWFx, PDF underlays all have different frame settings).

Note this value is used internally by AutoCAD, so the FRAME variable cannot be set to 3 by the User.

IMAGEFRAME, XCLIPFRAME, DWFFRAME, PDFFRAME and DGNFRAME can be set individually to a value of 0, 1 or 2 following the same conventions as per the FRAME variable above.

LWDISPLAY – Controls whether the lineweights of objects are displayed and can be set to either ON or OFF. Note that the setting is controlled separately for model space and all paper space layouts.

LAYEREVAL – Specifies whether the layer list is evaluated for new layers when added to the drawing or to the attached xrefs. Setting LAYEREVAL to 0 turns it off, 1 detects when new xref layers have been added in the drawing and 2 detects when new layers have been added in the drawing and xrefs.

LAYERNOTIFY – Specifies when an alert displays when unreconciled new layers are found and can be set to a bitcode value consisting of the following:

0   - Off
1   - Plot
2   - Open
4   - Load/Reload/Attach for xrefs
8   - Restore layer state
16 - Save
32 - Insert

Note: LAYEREVALCTL overrides the LAYEREVAL and LAYERNOTIFY setvars. When LAYEREVALCTL = 0 it acts like a global off (but not a global on). There is no effect even if LAYEREVALCTL is turned on if LAYERNOTIFY = 0 or LAYEREVAL = 0. LAYEREVALCTL must be set to 1 for LAYERNOTIFY and LAYEREVAL to function correctly.

As explained in the previous article,you can display a Dialog box showing the numerous AutoCAD variables available and their current settings using the System Variable Editor Express Tool.

A few useful AutoCAD system variables

AutoCAD has a number of system variables controlling all manner of options within the AutoCAD environment. Some variables act on a ‘per drawing’ basis whilst others affect the AutoCAD application itself. Today I’m going to run through a few of the common System-wide variables (i.e. those that affect the options within AutoCAD itself).

You can display a Dialog box showing the numerous system variables available and their current settings using the System Variable Editor Express Tool:

Generally most users will want to keep the system variables set to their default values but occasionally (particularly following a fatal crash) the variable may be left in an altered state and needs to be reset to a different value. The System Variable Editor can prove a useful resource to find out what the initial value of a variable would be and reset if required.

The following are just a few of the Registry variables that may need to be accessed and changed if the current value causes AutoCAD/AutoChart to not behave as expected.

Ever find your blocks or xrefs are inserting in the wrong place or at the wrong scale?

It seems to be a fairly common support query we get from a number of our customers – “I’m using the AutoChart Xref Data command and my Xrefs aren’t showing in my charts”. If this has happened to you, the chances are that you’ve run into the dreaded curse of the INSUNITS variable in AutoCAD – you are not alone!

Prior to AutoCAD 2006 the setting used for this variable had little effect on most users and consequently, most people didn’t pay it any attention or even know of its existence. However, from 2006 onwards Autodesk introduced a feature to automatically scale inserts and blocks according to the value set in the INSUNITS variable. All very nice and I’m sure it’s an extremely useful function for numerous AutoCAD users, unfortunately, if you’re unaware of what it does, mixing INSUNITS between drawings can lead to problems when inserting blocks and Xrefs.

To better understand what effect the variable can have, first we can take a look at its entry in the AutoCAD Help File:

Source: AutoCAD MAP 2010 Help Documentation

So you can see there are numerous settings relating to the distance units used within a drawing. When AutoCAD is installed the default template is normally acad.dwt (or map2d.dwt for AutoCAD MAP). If you inspect the value of INSUNITS for this template (by typing ‘insunits’ at the AutoCAD command line) you’ll see (assuming it hasn’t already been changed since installation) that it is set to 1 (or, according to the table above ‘inches’).

VISRETAIN, controlling the display of Xrefs

One fairly common question we get asked is from people who have inserted Xrefs into their charts and then subsequently changed colours, linetypes, layer settings etc. within the Xref. However, when viewing the Chart drawings, these changes to the Xref don’t appear to have been applied.

The solution lies within the AutoCAD drawing variable VISRETAIN

If VISRETAIN is set to 1, then the layer attributes set in the main Chart drawing rather than the Xref will be used. If you change VISRETAIN to 0 in the Chart Series drawings, then the layer attributes set in the Xref will take precedence.