Updating Velocity Based on ADC Channel C/C++ Code

The following example code is not necessarily complete, and may not compile if copied exactly. Refer to the examples folder on the NI-Motion CD for files that are complete and compile as is.

// Main function
void main(void)
{

   u8  boardID;             // Board identification number
   u8  axis;                // Axis number
   u16 csr   = 0;           // Communication status register
   i32 constant;            // Constant multiplier

   // Variables for modal error handling
   u16 commandID;           // The commandID of the function
   u16 resourceID;          // The resource ID
   i32 errorCode;           // Error code

   ///////////////////////////////
   // Set the board ID
   boardID= 1;
   // Set the axis number
   axis = 1;
   //  constant to multiply the ADC value read to calculate the required velocity
   constant = 10;
   ////////////////////////////////

   // Initialize onboard variable 4 to 0
   err = flex_load_var(boardID, 0, 4);
   CheckError;

   // Initialize onboard variable 1 to the constant multiplier
   err = flex_load_var(boardID, constant, 1);
   CheckError;

   // Begin onboard program storage - program number 1
   err = flex_begin_store(boardID, 1);

   // Set the operation mode to velocity
   err = flex_set_op_mode(boardID, axis, NIMC_VELOCITY);
   CheckError;

   // Insert Label number 1
   err = flex_insert_program_label(boardID, 1);
   CheckError;

   // Read ADC channel and store ADC value in variable 2
   err = flex_read_adc(boardID, NIMC_ADC1, 2);
   CheckError;

   // Multiply Variables 2 i.e. the ADC value with 1 i.e. the constant
   // Save the result in variable 3
   err = flex_mult_vars(boardID, 1, 2, 3);
   CheckError;

   // Subtract value in variable 3 from variable 4
   // We are not interested in the result - just want to
   // set the condition on board.
   err = flex_sub_vars(boardID, 3, 4, 0);
   CheckError;

   // Jump to label 1 as the subtraction above set the condition
   // to "equal to zero" which implies that the values in variable
   // 3 and 4 are the same
   err =  flex_jump_label_on_condition (boardID, 0, NIMC_CONDITION_EQUAL, 0,  0, NIMC_MATCH_ALL, 1/*label number*/);


   // Set the velocity for the move (in counts/sec) by loading the
   // value from variable 3 which is (adc value * constant)
   err = flex_load_velocity(boardID, axis, 0, 3);
   CheckError;


   // Start the move to update the velocity
   err =  flex_start(boardID, axis, 0);
   CheckError;

   // Save the value in variable 3 to variable 4 for use
   // in next cycle
   err = flex_read_var(boardID, 3, 4);
   CheckError;


   // Jump back to label 1 unconditionally
   err =  flex_jump_label_on_condition (boardID, 0, NIMC_CONDITION_TRUE, 0,  0, NIMC_MATCH_ALL, 1/*label number*/);
   CheckError;

   // End Program Storage
   err = flex_end_store(boardID, 1);


   // To execute this program use the Run Program function

   return;      // Exit the Application


   /////////////////////////////////////////////////////////////////////////
   // Error Handling
   //
   nimcHandleError; //NIMCCATCHTHIS:
   
   // Check to see if there were any Modal Errors
   if (csr & NIMC_MODAL_ERROR_MSG){
      do{
         // Get the command ID, resource and the error code of the modal
         // error from the error stack on the board
         flex_read_error_msg_rtn(boardID,&commandID,&resourceID,&errorCode);
         nimcDisplayError(errorCode,commandID,resourceID);

         // Read the Communication Status Register
         flex_read_csr_rtn(boardID,&csr);

      }while(csr & NIMC_MODAL_ERROR_MSG);
   }
   else       // Display regular error
      nimcDisplayError(err,0,0);
   return;    // Exit the Application
}