The Grid set up (GU=, GR=) and Unit set up (UR=), is established in the seed file (see section on SEED FILE parameters). Grids and Units are used on Schematic drawings only. These include P&ID's, Electrical schematics such as One-Line diagrams and Interconnection diagrams, Charts and Schedules. A grid or unit lock should never be used on a scaled drawing because it may result in inaccurate placement of elements.
The Grid and Units are set in the SEED.DGN file to:
|
GU=:.125 |
Grid Unit (space between grid points) |
|
GR=8 |
Grid Resolution (number of grid unit points per cross hair) |
|
UR=:.0625 |
Unit Resolution (smallest unit available for placing elements) |
The GRID DISPLAY will show the grid tick marks on the screen. The dots fall on every 1/8" point. The cross hairs fall on the 1" points. The UNIT points are not displayed on the screen. They fall at each 1/16" point, or on every grid mark and half way between every grid mark.
NOTE: The GRID and UNIT LOCKS force all elements to be placed on the grid or unit points. Always keep the GRID LOCK turned OFF, because the GRID LOCK will override the UNIT LOCK, and all elements will be forced to the 1/8" GRID rather than the 1/16" UNIT.
When working on a schematic drawing, proceed with these steps:
Turn GRID DISPLAY on
Turn UNIT LOCK on
Leave GRID LOCK off
All schematic type drawings should be created using the Unit Lock and Grid display. All cells for P&ID's and electrical schematics have been designed to fall on even grid points of 1/16".
Care should be taken to keep all line work on the grid. Schematic drawings that are not drawn on the grid and unit points will not be accepted.