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Common Command 37 / CAL037

Message posted by Jens ( : on 19 September 2012 at 10:51:30.

I have a Problem with Command 37 / CAL037.

My sensor has a LTL of 0 bar and a UTL of 400 bar. URV is 400 bar and LRV is 0 bar. The minimum range is 1% of UTL-LTL. URV has to be > LRV.
When I run CAL037 I get failure 6498 after the check of mid range.
First CAL037 asks me to set URV to UTL, so I enter 400.00.
Then I have to set the PV to mid range, so I set it to 200 bar.
Afterwards CAL sets the LRV to 200 bar. So my new range would be 200 - 400 bar.
Since it is not possible for the URV to be greater than UTL the sensor sends the response code - New Lower Range Value Pushed - and the URV remains on 400.
The new span is now 200 because the URV could not be pushed over the UTL.
Now CAL037 sends command 1 to the device to get the new value for the PV. The sensor answers 300 bar since it is still at 50 % of the measurement range and the new range is from 200 - 400 bar.
There I get the 6498 Failure since the values for PV are different.
What would be the correct behavior in this case?
If it is not allowed to change the span, then that would mean, that the only value that does not change the span would be 0 bar and I have to respond with - Aplied Process Too High - for every other value.

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