Integrated temperature evaluation
This rotary encoder features a temperature sensor integrated in the encoder electronics and
an evaluation circuit for an external temperature sensor. In both cases, the respective digitized
temperature value is transmitted purely serially over the EnDat protocol. It must be noted in
both cases that temperature measurement and transmission is not “safe” in the sense of
functional safety.
With regard to the internal temperature sensor, the rotary encoder supports a dual-level
cascaded signaling of exceeded temperature. It consists of an EnDat warning and an EnDat
error message.
In accordance with the EnDat specification, when the warning threshold of the internal
temperature sensor is reached, an EnDat warning is transmitted (EnDat memory area
“operating status,” word 1 – “warnings,” bit 2
1
– “temperature exceeded”). This warning
threshold for the internal temperature sensor is saved in the EnDat memory area “Operating
parameters,” word 6 – “trigger threshold” of the warning bit for “excessive temperature,”
and can be individually adjusted. A device-specific default value is saved here when the
encoder is shipped. The temperature measured by the internal temperature sensor is higher
by a device-specific and application-specific amount than the temperature at the measuring
point M1 according to the dimension drawing.
The rotary encoder features a further, but nonadjustable, trigger threshold for the EnDat
error message “temperature exceeded” of the internal temperature sensor which, when
triggered, transmits an EnDat error message (EnDat memory area “operating status,” word
0 – “error messages,” bit 2
2
– “position,” and in the additional datum 2 “operating status
error sources”, bit 2
6
– “temperature exceeded”). This trigger threshold depends on the
encoder model and is shown in the specifications.
Depending on the application, HEIDENHAIN recommends adjusting the threshold sensitivity
so that it lies below the trigger threshold for the EnDat error message “temperature
exceeded” by a sufficient value. Compliance with the permissible operating temperature with
respect to the measuring point M1 is definitive for the intended use of the encoder.