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.

• SDI – Controls whether multiple drawings can be opened in a single session of AutoCAD. If SDI is set to 0 then opening more than one drawing at a time will take place within a single AutoCAD session (the required drawing can then be selected from the Window menu). However, if SDI is set to 1, then only one drawing can be open at a time within the single AutoCAD session (and double clicking a dwg within Explorer will start a new AutoCAD session). AutoChart users may find that SDI becomes set to 1 if an AutoChart Chart Series command crashes part way through operations. To reset it, simply type ‘SDI’ at the AutoCAD command line and set it to 0.
• FILEDIA –Controls whether a File Dialog box is displayed when opening or saving a drawing. If FILEDIA is set to 0, theXREFn the file path needs to be entered at the AutoCAD command line and no dialog box is displayed. If FILEDIA is set to 1 then a Dialog box is presented allowing the user to browse to the required file location.
• ATTDIA –Controls whether a Dialog box is presented when a Block with attributes is inserted. If ATTDIA is set to 0 then the Attribute information is entered at the AutoCAD command line, if it is set to 1 then a Dialog box is presented allowing the user to enter the attributes into the Dialog box. When using AutoChart with block operations (e.g. Import Block, Create Kps, etc.) then the value of ATTDIA must be set to 0.
• ATTREQ –Controls whether the user is prompted to enter the block attributes when the block is inserted (ATTREQ = 1) or whether the attribute defaults will be used (ATTREQ = 0). For use in AutoChart, ATTREQ should be set to 1.
• PICKFIRST – Controls whether you select objects before or after you issue a command. If PICKFIRST is set to 0, you select objects after you have issued a command (i.e. any oblects that are selected before the command is run are deselected). If PICKFIRST is set to 1 then you can select objects before running a command (i.e. any objects that are already selected are passed to the command).
• XREFNOTIFY – Controls notification for updated or missing Xrefs. If XREFNOTIFY is set to 0 then notification is disabled, if it is set to 1 then notification by icon in the tray area is enabled. If XREFNOTIFY is set to 2 then this enables notification of changed or missing Xrefs by icon and balloon messages in the tray area.
• XDWGFADECTL – AutoCAD 2010 introduced a feature whereby Xrefs could be shown as dimmed so that they display differently from entities within the drawing itself. XDWGFADECTL controls the degree of fading of the Xref in the main drawing and can be set to any value between -90 and 90. If it is set to 0 then the Xrefs are not displayed as faded. If it is set to a positive number then this controls the percentage of fading up to a maximum of 90%. If the value is set to a negative value then the Xref is not faded but the value is stored to allow easy toggling of the fade state simply by changing the sign of the value.

Next time, I’ll cover some of the common Drawing specific variables that can have an effect on a per drawing basis.