Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Next revision		Previous revision
daq-and-datalogging:documents:analog-input-signal-connections-1 [2023/06/14 06:03] – created Scandiwebdaq-and-datalogging:documents:analog-input-signal-connections-1 [2023/07/27 21:29] (current) – Arthur Brown
Line 1: Line 1:
-====== TechTip: ====== +====== TechTip: Basic Analog Input Signal Connections (Part 1) ======
- +
-===== Basic Analog Input Signal Connections (Part 1) =====+
  
 **Objective**\\  **Objective**\\ 
Line 22: Line 20:
 Single-ended inputs measure the voltage between the input signal and analog ground (AGND) (see Figure 1). Because they require only one physical connection per input, a single-ended configuration can monitor twice as many channels than the two-connection differential configuration using the same connector and onboard multiplexer.\\  Single-ended inputs measure the voltage between the input signal and analog ground (AGND) (see Figure 1). Because they require only one physical connection per input, a single-ended configuration can monitor twice as many channels than the two-connection differential configuration using the same connector and onboard multiplexer.\\ 
  
-{{https://files.digilent.com/resources/measurement-computing/Reference Images/SE-config.png?321x196}}\\ +{{https://files.digilent.com/reference-images/SE-config.png?321x196}}\\ 
  
 **Differential Inputs**\\  **Differential Inputs**\\ 
Line 28: Line 26:
  
  
-{{https://files.digilent.com/resources/measurement-computing/Reference Images/picture 12.png?382x442}}\\ +{{https://files.digilent.com/reference-images/picture 12.png?382x442}}\\ 
  
 Common Mode Voltage and Common Mode Range\\  Common Mode Voltage and Common Mode Range\\ 
Line 37: Line 35:
 Figure 3 shows a single-ended configuration with a common mode voltage (Vcm). Any voltage difference between grounds g1 and g2 shows up as an error signal at the input amplifier. If an ideal common point is not available for single-ended inputs, a differential input configuration is needed.\\  Figure 3 shows a single-ended configuration with a common mode voltage (Vcm). Any voltage difference between grounds g1 and g2 shows up as an error signal at the input amplifier. If an ideal common point is not available for single-ended inputs, a differential input configuration is needed.\\ 
  
-{{https://files.digilent.com/resources/measurement-computing/Reference Images/SE-comm-mode.png?503x175}}\\ +{{https://files.digilent.com/reference-images/SE-comm-mode.png?503x175}}\\ 
  
 A differential input configuration is more immune to EMI than a single-ended configuration because differential connections cancel or ignore common-mode voltages and can measure the difference between the two connected points. The rejected common mode voltages can be steady dc levels or noise spikes.\\  A differential input configuration is more immune to EMI than a single-ended configuration because differential connections cancel or ignore common-mode voltages and can measure the difference between the two connected points. The rejected common mode voltages can be steady dc levels or noise spikes.\\ 
  
-{{https://files.digilent.com/resources/measurement-computing/Reference Images/DIFF-comm-mode.png?500x174}}\\ +{{https://files.digilent.com/reference-images/DIFF-comm-mode.png?500x174}}\\ 
  
 Vcm is ignored in a differential input configuration, but only within a range called the common mode range. Typically, a device amplifier in differential mode has a common mode range of ±10 V. The common mode voltage combined with the signal voltage – Vcm + Vs – must remain within this range.\\  Vcm is ignored in a differential input configuration, but only within a range called the common mode range. Typically, a device amplifier in differential mode has a common mode range of ±10 V. The common mode voltage combined with the signal voltage – Vcm + Vs – must remain within this range.\\ 
Line 47: Line 45:
 The common mode voltage range of ±10 V is shown graphically in Figure 5.\\  The common mode voltage range of ±10 V is shown graphically in Figure 5.\\ 
  
-{{https://files.digilent.com/resources/measurement-computing/Reference Images/comm-mode-range.png?439x374}}\\ +{{https://files.digilent.com/reference-images/comm-mode-range.png?439x374}}\\ 
  
 An input signal cannot be measured if it is more than 10 V from the device AGND, even in differential mode. For example, the device cannot measure the difference between 13 V and 14 V as 1 V due to the ±10 V common mode range limitation. An input signal cannot be measured if it is more than 10 V from the device AGND, even in differential mode. For example, the device cannot measure the difference between 13 V and 14 V as 1 V due to the ±10 V common mode range limitation.
Line 78: Line 76:
 Some signal sources are already electrically-isolated from the device. Figure 6 shows a typical isolated ground system. These signal sources are often battery-powered, or are complex equipment. Isolated ground systems provide excellent performance, but require care to ensure optimum performance. Refer to TechTip: Basic Analog Signal Connections (Part 2) for more details.\\  Some signal sources are already electrically-isolated from the device. Figure 6 shows a typical isolated ground system. These signal sources are often battery-powered, or are complex equipment. Isolated ground systems provide excellent performance, but require care to ensure optimum performance. Refer to TechTip: Basic Analog Signal Connections (Part 2) for more details.\\ 
  
-{{https://files.digilent.com/resources/measurement-computing/Reference Images/SE-Iso.png?691x241}}\\ +{{https://files.digilent.com/reference-images/SE-Iso.png?691x241}}\\ 
 **Figure 6.** Signal source and AI DAQ device sharing common ground connected to single-ended input\\  **Figure 6.** Signal source and AI DAQ device sharing common ground connected to single-ended input\\ 
  
- +**More Information**\\  
-More Information\\  +Please reach out to our support team on the Digilent Forum if you have any questions: [[https://forum.digilent.com/]]
-Please contact Measurement Computing Corporation if you have any questions or if you would like any further information.\\  +
- +
-  *Knowledgebase: [[https://kb.mccdaq.com/Default.aspx | kb.mccdaq.com]] +
-  *Phone: 508-946-5100 +
-  *Fax: 508-946-9500+
      
-Additional TechTips are available on our [[https://www.mccdaq.com/Technical-Articles | Data Acquisition Technical Articles web page.]]+Additional TechTips are available here in Digilent Reference: [[start]]