Opening Physical Constraints Files

Physical Constraints Files (PCF) contain physical constraint information. They apply only to FPGAs, because CPLD timing information is contained in the (VM6) design file itself. The order of the timing constraints in the PCF file is reflected by the Timing Analyzer. This section describes methods for loading and opening Physical Constraints Files.

Automatically Opening a Physical Constraints File

When you open a design using File Open Design, the Timing Analyzer automatically loads the default Physical Constraints File if it exists. The default Physical Constraints File is a physical constraints file with the same name as the design in the same directory as the design file.

A message similar to the following appears on the right side of the status bar at the bottom of the Timing Analyzer window.

/home/user/ta/designs/design10.pcf

If there is no default physical constraints file, a message box appears with a message similar to the following.

No default Physical Constraints File found for design "/home/user/ta/designs/design10.ncd"

Manually Opening a Physical Constraints File

If you already have a design open and wish to load a different Physical Constraints File for use with the current design, follow these steps.

1. Select File Open Physical Constraints.
   
   The Open Physical Constraints dialog box appears.
   
   
2. In the Look in/Directories list box, click on the directory containing the PCF file to load.
   
   
3. Under Files of Type/List Files of Type, Physical Constraints (*.pcf) is the default and the only file type you can select.
   
   All the available PCF files are displayed in the list box.
   
   
4. Select a PCF file from the list box, or type the name in the field below File name. (*.pcf appears by default; backspace over the asterisk before typing in the physical constraints file name.)
   
   
5. Click OK.
   
   The Timing Analyzer reads the PCF file and the path name appears on the right side of the status bar at the bottom of the Timing Analyzer window.
   
   

Viewing a Physical Constraints File

In some cases you may want to open a PCF file for viewing from within the Timing Analyzer. When you open a PCF file by this method, the Timing Analyzer does not load the PCF file for use with the current design. It just opens the file for viewing but does not replace the PCF file that is loaded for use with the current design. To open a PCF file in this way, follow these steps.

1. Select File Open.
   
   The Open dialog box appears.
   
   
2. Under Files of Type/List Files of Type, select All Files (*.*).
   
   
3. Select a PCF file from the list box, or type it in the field below File Name.
   
   
4. Click OK.
   
   

The PCF file is displayed in a window but the path name on the right side of the status bar at the bottom of the Timing Analyzer window does not change since opening a PCF file by this method does not load the PCF file for processing with the current design.