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Analog Output: Voltage and Position don't match

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I am using Kollmorgen servo motor with AKD drive. The feedback type is Endat 2.1. 
Now in the Analog Output, according to the position scaling

Position(Degrees) = 36 * Analog Output(Volts)

But I observed that this is not the case. I have attached a screenshot. Here the output is 3.455 V. 
So Pos(Degree) = 36 * 3.455 = 124.380 degree which is not equal to the position displayed in the workbench 125.129 degree.
Whats the reason behind this?

image

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2 Answers

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Here is the following result from my test The math seems to be correct. I am sure there is rounding. Since you have a "CC" drive are you not using CanOpen or EtherCAT? Those fieldbuses would provide a better way to read the actual position. That drive also supports Modbus TCP via the Service/HMI Ethernet Port ( X11 ) and the position feedback can be read using that protocol as well.

image

 

 

 

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I am not using Ethercat. For communication I am using Analog with position indexer. Thanks for the suggestion and the answer.

Santosh - Wed, 02/19/2020 - 12:56
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I replicated your problem in firmware 1-18-04 but when I updated the firmware to the latest 1-19-00-002 and the expected voltage based on the math was correct.

This appears to have been a bug in the older firmware.

 

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I updated the firmware to the latest version which is AKD-P-NBCC-V01-19-00-002.i00. The problem still exists. Though now the position displayed is more close to the position calculated from the output voltage (only the last two decimal digits don't match). Is this due to rounding off?

Santosh - Wed, 02/19/2020 - 12:16
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