Description of Sensor Parameters
2
0
1
7
-0
6
57
8.4.8
Temperature Compensation
The speed of sound and subsequently an ultrasonic sensor
’
s accuracy is affected by changes
in ambient temperature. By using the "Temperature compensation" parameter, you can switch
the sensor
’
s integral automatic temperature compensation off and on.
When this parameter is enabled, the distance value is calculated taking into account the
ambient temperature continuously measured by the sensor. This method automatically
corrects measuring errors resulting from a changing ambient temperature and thus greatly
improves the measuring accuracy of the sensor.
If disabled, the distance value is calculated on the basis of the temperature value provided by
the "operating temperature" parameter.
Temperature Compensation in Practice
With active temperature compensation, ambient temperature is measured within the sensor
housing. The accuracy of this temperature measurement can be falsely influenced by external
influences which heat or cool the sensor housing. Such influences can be, for example:
■
Solar radiation
■
High load on the sensor output resulting in a great deal of heat within the sensor housing
■
Cleaning the sensor with cold water
In applications with significant fluctuations in ambient temperature, e.g., as a result of heat
produced by machines and/or processing, or outside, we generally recommend enabling
temperature compensation
In applications with an almost constant temperature, e.g., in large tanks, it may be useful to
disable automatic temperature compensation. This is useful because then other influences
(see note) will not impact measurement accuracy.
Note!
This parameter is visible in the DTM advanced view.
Parameter name
Access
Value range
Temperature compensation
Read/write
■
Disabled
■
Enabled
Table 8.27
Note!
Internal temperature compensation can be disabled if the ambient temperature of the ultrasonic
sensor is measured on the process side. The measured value of the ultrasonic sensor can then
be corrected in the downstream logic unit taking into account the measured ambient
temperature.
