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CN0209: Universal AFE questions



		

			

									
						jartigas
					
							

			
				
									
											
							 		
		        	            							
			
			    	
			                    
                
				                on Oct 26, 2011 
				
			
			
		


				
		

		    		    
		    
		    	
			
1- How would I do the same circuit for 8 channels (CN0209 is for 2 channels), and with minimal components? (RTD 2-3 wires (no 4 wires), TC, 4-20mA)

 
2- What is the configuration of the ADG1414 for each measurement mode?

 
3- What is the correct connection for TC (figure 2)? The connection is JX-3, JX-3 ???????

 
Thanks a lot.

								


				
				
		

			
						
									
									
						
						
			
			
			
			
		


					

			





	

		
	















	

	

					



			








	
	
	
	



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													0
							
			
				
									
							        
            
                                    			
			                            
                        
                on Nov 10, 2011 3:05 PM
            
            
					
    
	
    

		
		
    
					
    Hi Ching.
    
 
    First of all, the initial requeriments of my project:
    
 
         - 8 universal analog inputs (RTD, TC, 4-20, Voltage). 3 header pins.
    
 
         - Each channel can be configurated independently for RTD, TC ... measurement mode. Another choice if this option complicates the design (cost &      component number (PCB size)), 2 blocks (4+4 inputs) and can configurated each block for each measurement mode.
    
 
         - The sample rate is not a critical factor.
    
 
         - This is controlled for a 32 bits ARM Cortex kinetis, communications Ethernet, CAN and RS-485. It´ll be a web based application.
    
 
         I´ll configure each analog input (with switches and analog multiplexers, jumpers no allowed), with a software through communications, and monitoring         too.
    
 
     
 
    
 
     
 
    
 
    
  (1) The inputs must be differential.  I've thought about putting 2 ADCS (1 for each block).
 
    
 
     
 
    
 
    
  (2) Sorry, i want give you the phone number, but i don´t speak English.
 
    
 
    
  
    
  
    
   
    
         I attempt to explain how the circuit works (CN-0209),  and if I'm wrong tell me.
   
    
   
     
   
    
   
    
         mA input: single ended, through AIN4, AIN8.
   
    
   
    
         Voltage input: Single ended, closed the switches of ADG1414, tied to AD8676-AD8275-AIN3
   
    
   
    
         TC input: Differential, through ADG442-(AIN1-AIN2)&(AIN5-AIN6). AD8617 is used in the path of thermocouple circuit?? is my doubt.
   
    
   
    
         RTD input: Differential, through ADG442-(AIN1-AIN2)&(AIN5-AIN6). AD8617 is used for current source.
   
    
   
    
    (3) Solved.
   
    
   
     
   
    
   
    
    I don´t have the EVAL-CN0209-SDPZ, i am doing my own prototipe board.
   
    
   
     
   
    
   
    
    Regards.
   
    
  
    
 
    
 
    
  
     
  
    
 
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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													0
							
			
				
									
							        
            
                                    			
			                            
                        
                on Nov 10, 2011 3:05 PM
            
            
					
    
	
    

		
		
    
					
    Hi Ching.
    
 
    First of all, the initial requeriments of my project:
    
 
         - 8 universal analog inputs (RTD, TC, 4-20, Voltage). 3 header pins.
    
 
         - Each channel can be configurated independently for RTD, TC ... measurement mode. Another choice if this option complicates the design (cost &      component number (PCB size)), 2 blocks (4+4 inputs) and can configurated each block for each measurement mode.
    
 
         - The sample rate is not a critical factor.
    
 
         - This is controlled for a 32 bits ARM Cortex kinetis, communications Ethernet, CAN and RS-485. It´ll be a web based application.
    
 
         I´ll configure each analog input (with switches and analog multiplexers, jumpers no allowed), with a software through communications, and monitoring         too.
    
 
     
 
    
 
     
 
    
 
    
  (1) The inputs must be differential.  I've thought about putting 2 ADCS (1 for each block).
 
    
 
     
 
    
 
    
  (2) Sorry, i want give you the phone number, but i don´t speak English.
 
    
 
    
  
    
  
    
   
    
         I attempt to explain how the circuit works (CN-0209),  and if I'm wrong tell me.
   
    
   
     
   
    
   
    
         mA input: single ended, through AIN4, AIN8.
   
    
   
    
         Voltage input: Single ended, closed the switches of ADG1414, tied to AD8676-AD8275-AIN3
   
    
   
    
         TC input: Differential, through ADG442-(AIN1-AIN2)&(AIN5-AIN6). AD8617 is used in the path of thermocouple circuit?? is my doubt.
   
    
   
    
         RTD input: Differential, through ADG442-(AIN1-AIN2)&(AIN5-AIN6). AD8617 is used for current source.
   
    
   
    
    (3) Solved.
   
    
   
     
   
    
   
    
    I don´t have the EVAL-CN0209-SDPZ, i am doing my own prototipe board.
   
    
   
     
   
    
   
    
    Regards.
   
    
  
    
 
    
 
    
  
     
  
    
 
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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