Ghosting on Motion Controller Analog Inputs Primary Software: Driver Software>>NI-Motion/FlexMotionPrimary Software Version: 7.5 Primary Software Fixed Version: N/A Secondary Software: N/A Hardware: Motion Control>>Controllers
Problem: I have an NI-73xx Motion controller and I am using the analog input to read an analog signal. I have hooked up my signal to analog input channel 3, but in my program I am reading from analog input 1. Even though I am reading from a different channel than what I have connected, I still see the correct value of the signal on channel 1. Why do I see my signal that is connected to channel 3 when I read from channel 1 in software? Solution: Similar to data acquisition devices, the analog input channels on the NI-Motion controllers are multiplexed and can exhibit ghosting if the proper precautions are not taken. If you do not ground the other analog input lines, then the value on the input that you are connecting your signal to can be seen on the other lines. To help prevent ghosting on the analog inputs of a motion controller, keep in mind that grounding unused analog input lines will help reduce ghosting and incorrect readings on other lines. For more details and suggestions, follow the instructions in the following KnowledgeBase document: How Do I Eliminate Ghosting From My Measurements? Related Links: KnowledgeBase 28MF7JQO: Troubleshooting Unexpected Voltages, Floating, or Crosstalk on Analog Input Channels Attachments:
Report Date: 08/18/2007 Last Updated: 04/25/2008 Document ID: 4CHLBSHB |
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