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Hello, I have a problem with messuring temperatures.
The setup goes as follows - V700 - EX-A2X - IO-PT4K-PT1000 sensor.
IO-PT4K type is PT100/1000(alpha=0.392) mode is Celsius . I get values like 220, 200 that seems to be like temperature 22 multiplied by 10. Why are these values so high or it is just coinsidense. Also the keep changing like from 170 to 220 in seconds so I can't build control based on temperature messuring. Any thoughts?
 

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Thermocouple inputs normally have an implied decimal point to give you a reading in tenths of a degree. Either display the value using the implied decimal, or divide by 10 to get an integer value.

There are filters available to help stabilize the temperature reading, if needed.

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There is a filter built-in to the Hardware Configuration for the sensor input. In addition, there are filter Function Block options available under the Function Block (FB) drop down menu when in ladder view.

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But if you are having such large variations on a PT100/1000 I suspect there is something wrong in the wiring.  Long run? Screened?  Correctly terminated including the screen?  A myriad of other things to look at.  The reading should innately be very stable.

cheers,

Aus

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On August 16, 2017 at 5:41 PM, Ausman said:

But if you are having such large variations on a PT100/1000 I suspect there is something wrong in the wiring.  Long run? Screened?  Correctly terminated including the screen?  A myriad of other things to look at.  The reading should innately be very stable.

cheers,

Aus

Screened must be the Austrialian term for shielded. Screen makes me think of the second grid in a pentode electron tube. The British call electron (vacuum) tubes "vavles". Which makes sense, they are valves for electrons. 

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