Resolution, Accuracy And Tolerances; Resistance Signals - ABB i-bus KNX Product Manual

®
ABB i-bus KNX
Device technology
2.1.5

Resolution, accuracy and tolerances

Please note that the tolerances of the sensors which are used will need to be added to the listed values.
With sensors based on resistance measurement, it is also necessary to consider the cable error.
In the supplied state of the device, the stated accuracies will not be initially achieved. After initial
commissioning, the device performs an autonomous calibration of the analogue measurement circuit. This
calibration takes about an hour and is performed in the background. It is undertaken regardless of whether
or not the device is parameterized and is independent of the connected sensors. The normal function of
the device is not affected. After calibration has been completed, the calibration values which have been
determined will be stored in the non-volatile memory. Thereafter, the device will achieve this level of
accuracy every time it is switched on. If the calibration is interrupted by programming or bus voltage failure,
it will recommence every time it is restarted. The ongoing calibration is displayed in the status byte by a 1
in bit 4.
2.1.6

Resistance signals

Sensor signal
PT100*
PT1000*
KT/KTY 1,000*
KT/KTY 2,000*
3
* in addition to current measured value at ambient temperature (T
4
* incl. cable and sensor errors
14 2CDC508134D0202 | FCA/S 1.x.x.1
Resolution Accuracy
at 25 °C T
4
0.01 ohm ±0.15 ohms
4
0.1 ohm ±1.5 ohms
4
1 ohm ±2.5 ohms
4
1 ohm ±5 ohms
Accuracy Accuracy
at 0...50 °C T at -20...70 °C T
3 3
* *
u u
±0.2 ohms ±0.25 ohms
±2.0 ohms ±2.5 ohms
±3.0 ohms ±3.5 ohms
±6.0 ohms ±7.0 ohms
)
u
Remark
3
*
u
0.1 ohm = 0.25 °C
1 ohm = 0.25 °C
1 ohm = 0.125 °C/at 25 °C
1 ohm = 0.064 °C/at 25 °C