Emerson Exchange 365

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Value in AI Block 1/1000 of value on display, diagnostics display correct value

The connection is via Modbus to a Watlow controller.  The value displayed on the Watlow matches the value shown in diagnostics.  I can write to the unit fine and with the correct values.  Any idea where the scaling issue could be?  

Elizabeth Sanford

• 18 Jun 2018 1:17 PM
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4 Replies

• Alfred Pol

  

  • 18 Jun 2018 1:39 PM

  What are the settings for the parameters OUT_SCALE, XD_SCALE and L_TYPE in the AI functionblock?

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• Elizabeth Sanford

  

  • 18 Jun 2018 3:24 PM

  In reply to Alfred Pol:

  Thank you. XD_SCALE was 1000x the other scales.

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• PRASHANT-MUTTEPAWAR

  

  • 18 Jun 2018 4:52 PM

  In reply to Alfred Pol:

  Direct L_TYPE means XD_SCALE is not used (OUT_SCALE will be copied to XD_SCALE) and FIELD_VAL would be typically used for when getting a decimal Hart value.
  
  Indirect L_TYPE is scaled in linear fashion, this is typically the 4-20mA use case with DST using FIELD_VAL_PCT, XD_SCALE is 0-100% and OUT_SCALE is the range of the instrument.
  
  Direct Indep L_TYPE means the value isn't scaled at all and XD_SCALE is still used with value plugged into OUT_SCALE. With RTD of range -200 to 1000 °C the XD_SCALE would be set to this range but you probably don't want to display this entire range to operations so the OUT_SCALE is set to the range you wish to see, 0-150 °C for example.
  
  Indirect Sqr Root L_TYPE would have XD_SCALE as the full scale differential pressure of a flow orifice and the OUT_SCALE would be the associated flow rate for that scale.

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• Nathan Hunt

  

  • 3 Sep 2020 11:00 PM

  Could you share your configuration? I'm struggling to get mine set up to my watlow ez zone.

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