gf.c

机械工业出版社 Lab Windows/CVI逐步深入与开发实例源代码

/***************************************************************************** 
 *  Copyright 1998 National Instruments Corporation.  All Rights Reserved.   * 
 *****************************************************************************/

    /*=Sung:===============================================================*
                INSTRUCTIONS TO THE INSTRUMENT DRIVER DEVELOPER
                         READ THESE INSTRUCTIONS FIRST!
     *=======================================================================*
                                                                             
        Congratulations!  You have successfully created all the files needed
        for your instrument driver - *.c,  *.h, *.fp, and *.sub.  These     
        files give you a framework to build your complete instrument driver 
        with the following features:                                    
            - IVI compliance                                             
            - VXIplug&play compliance                                    
            - Attribute model                                           
            - State caching                                             
            - Simulation                                                
            - Multithread safety                                         
                                                                        
        Before you can begin using this driver, you must perform the following 
        manual changes.                                 
                                                                        
        - If you are developing a driver for a register-based device, 
          remove the function panels for the GF_WriteInstrData 
          and GF_ReadInstrData functions.  These functions
          are for use with message-based instruments.                                       
                                                                            
        - Device-specific changes are marked with the comment "Sung".      
          Search for all occurrences of the word "Sung" and make the changes 
          for your specific instrument.  Delete the comments after you complete 
          the changes.
          
        - The IVI wizard might not properly align the code it generates.
          Review the resulting *.h and *.c files and reformat them as necessary.
          
        - Read the help text for the functions and attributes to understand
          the functionality you must implement in this driver.  The easiest
          way to view the help text is by using the GF.fp 
          function panels in "operate" mode.  You can view the help text for
          the attributes in any of the GF_GetAttribute 
          function panels.

        - Many of the functions contain extensive code examples within 
          comment blocks.  These code examples contain embedded comments.
          The only way to embed comments is by using double slashes (//).  
          Some C compilers do not accept double slashes.  If you are developing 
          this driver for general use, convert the double slashes to 
          traditional C comment markers.
        
        - Edit the Function Panel help.  Pay close attention to the default
          values and valid ranges for each parameter.  If you change the 
          default value for a control, you also need to change the default
          value in the help for the control.  Also, search for the comment 
          "Sung" in the help text, and make the appropriate changes.
          
        - Edit the help for all attributes with the attribute editor.  Pay close
          attention to the valid range information.  The Set/Get/Check attribute
          function panels automatically display valid range information for 
          attributes that have range tables of type IVI_VAL_DISCRETE or 
          IVI_VAL_COERCED.  You must edit/create the valid range information 
          in the description of an attribute if any of the following conditions 
          is true:
            * The attribute does not have a range table.
            * The attribute has a range table of type IVI_VAL_RANGED.
            * The attribute uses multiple static range tables or a dynamic
              range table.
            
          Also, look for "Sung" comments in the help text, and make the 
          appropriate changes.
           
        - Verify that all values that the header file defines are valid for 
          your instrument.  Delete the values that your instrument does not 
          use.
            
        - Delete these instructions and save the modified program.         

	 *=======================================================================*
	                                                                             
	    This driver has functions and attributes that are common to most 
	    function generators.  The functions and attributes have example code 
	    with instructions on how you can modify the code for your specific 
	    function generator.  This section provides additional modification 
	    instructions regarding special situations you might encounter or the 
	    relationships between elements of this driver.  The instructions in
	    the example code sections reference these comments when applicable.
	    
	    - NOTE REGARDING CONFIGURATION STATE
	      The example code in this driver makes the following assumptions:
	      
	      - The function generator can be configured only when in a Configuration
	        state.
	      
	      - The driver must check to be sure it is in the Configuration state
	        before attempting to make changes to the instrument's settings.
	    
	      - The instrument is not configurable while it is generating a signal.
	        The GF_InitiateGeneration function moves the instrument
	        into a non-configurable state, and the GF_AbortGeneration
	        function moves it to the Configuration state.
	        
	      - The GF_VerifyConfigurable utility function 
	        encapsulates the code that checks if the instrument is currently
	        configurable.
	      
	      If you cannot query your instrument directly to determine configurability,
	      do the following:
	    
	      - Remove the GFAttrConfigurable_ReadCallback and
	        GFAttrConfigurable_WriteCallback functions.
	      
	      - At every point in the driver that changes the configurability of the
	        instrument, call the Ivi_SetAttributeViBoolean function to change the
	        value of the hidden attribute GF_ATTR_CONFIGURABLE
	        to reflect the current state of the instrument.
	     
	      If some attributes can be set regardless of your instrument's Configuration
	      state, do the following:
	   
	      - Remove the call to the GF_VerifyConfigurable utility function
	        from the attribute's callback functions.
	     
	      If you can configure your instrument while it is not in the Configuration
	      state, do the following:
	      
	      - Delete the GF_ATTR_CONFIGURABLE attribute and the
	        GFAttrConfigurable_ReadCallback and GFAttrConfigurable_WriteCallback
	        functions.  Remove the Ivi_AddAttribute function that adds the attribute to the
	        driver.  Delete the GF_VerifyConfigurable utility function's
	        prototype and definition, and remove any reference to it in the source code.  
	   
	    - NOTE REGARDING GF_ATTR_OUTPUT_MODE
	      The example code in this driver makes the following assumptions:
	      
	      - Some of the function generator's attributes can be configured only
	        when the instrument is set to produce a certain kind of output.
	        
	      - The output modes available are Standard Function and Arbitrary Waveform.
	      
	      - The driver must check that it is in the correct output mode before it
	        attempts to read or write some attributes.
	        
	      - The GF_VerifyOutputMode utility function verifies that
	        the instrument is set to the correct output mode.
	        
	      You should make the following changes throughout your driver:
	      
	      - Remove any calls to GF_VerifyOutputMode that you
	        do not need
	        
	      - Add any calls to GF_VerifyOutputMode that your driver
	        requires and that are not already present in the example code.
	        
	      - Change any calls to GF_VerifyOutputMode that check for an output
	        mode other than the one your instrument requires.
	        
	      If your instrument supports only one output mode, do the following:
	      
	      - Delete the GFAttrOutputMode_WriteCallback and 
	        GFAttrOutputMode_ReadCallback functions, and modify the
	        attrOutputModeRangeTable range table so that the only valid value is
	        the output mode your instrument supports.
	      
	      - Pass the value of the output mode your instrument supports as
	        the default value parameter of the Ivi_AddAttribute function that
	        adds the GF_ATTR_OUTPUT_MODE attribute to the
	        driver.
	        
	      - Remove all calls to the GF_VerifyOutputMode utility
	        function and remove any other references in the driver that check the 
	        GF_ATTR_OUTPUT_MODE attribute.
	      
	      If an attribute can be read or written regardless of the output mode,
	      do the following:
	      
	      - Remove calls to the GF_VerifyOutputMode utility function
	      from the attribute's Callback functions.
	      
	      If an attribute can be set under more than one output mode, but not all
	      of them, do the following:
	      
	      - Remove calls to the GF_VerifyOutputMode utility function
	      from the attribute's Callback functions.
	      
	      - Use the Ivi_GetAttributeViInt32 function to read the current output mode
	      from the GF_ATTR_OUTPUT_MODE attribute, and an if-else
	      structure to determine if the instrument is in one of the correct output
	      modes.  If the output mode is not correct, return the
	      GF_ERROR_INVALID_MODE error.
	      
	      If your instrument supports different output modes than those used
	      in the examples, do the following:
	      
	      - Modify the attrOutputModeRangeTable range table so that it contains
	        valid values for all output modes your instrument supports.
	        
	 *=======================================================================*
	    
	    The following sections list groups of attributes and functions that are 
	    optional.  This driver has these functions and attributes, but you do not 
	    have to implement them in the driver for your specific instrument.
	    If you choose to implement one of the attributes or functions listed below, 
	    you must implement all of the attributes and functions that belong to 
	    the same group, unless otherwise noted.
	    
	    NOTE: You must implement either the Standard Waveform Group or the
	          Arbitrary Waveform Generation Group.  You may implement both
	          of them.