Commissioning Cerabar PMP21 IO-Link
32 Endress+Hauser
Prerequisite The pressure value present is automatically adopted as the zero point.
An offset is possible (parallel shifting of the sensor characteristic) to correct the
orientation and any zero point drift. The accepted value of the parameter is subtracted
from the "raw measured value". The requirement to be able to perform a zero point shift
without changing the span is met with the offset function.
Maximum offset value = ± 20 % of the sensor nominal range.
If an offset value is entered that shifts the span beyond the physical limits of the sensor,
the value is admitted but a warning message is generated and displayed via IO-Link. The
warning message only disappears when the span is within the sensor limits, taking the
offset value currently configured into consideration.
The sensor can
• be operated in a physically unfavorable range, i.e. outside its specifications, or
• be operated by making appropriate corrections to the offset or span.
Raw measured value – (manual offset) = display value (measured value)
Example 1 • Measured value = 0.002 bar (0.029 psi)
• Use the Zero point adoption (GTZ) parameter to correct the measured value with the
value, e.g. 0.002 bar (0.029 psi). This means that you are assigning the value
0 bar (0 psi) to the pressure present.
• Display value (measured value) after position adjustment = 0 bar (0 psi)
• The current value is also corrected.
• Where applicable, check and correct switch points and span settings.
Example 2 Sensor measuring range: –0.4 to +0.4 bar (–6 to +6 psi) (SP1 = 0.4 bar (6 psi); STU =
0.4 bar (6 psi))
• Measured value = 0.08 bar (1.2 psi)
• Use the Zero point adoption (GTZ) parameter to correct the measured value with the
value, e.g. 0.08 bar (1.2 psi). This means that you are assigning the value 0 mbar (0 psi)
to the pressure present.
• Display value (measured value) after position adjustment = 0 bar (0 psi)
• The current value is also corrected.
• Warnings C431 or C432 appear because the value 0 bar (0 psi) was assigned to the real
value of 0.08 bar (1.2 psi) present and the sensor measuring range was thus exceeded
by ± 20%.
SP1 and STU values must be readjusted downwards by 0.08 bar (1.2 psi).
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