10 Configuring the control’s inputs and outputs
PHLOX - Ignition Control System 61
10.2.2 Filtering of analogue inputs
The measured value of the analogue input can be filtered through a digital filter. The re-
spective parameter is stored at number 1514 AnalogIn1_Filter.
In this parameter the time constant is entered in seconds. A value of 0.00 s corresponds
to no filtering. For normally fast sensor changes, a filter value 0.10 s will be appropri-
ate. For measuring quantities that change more slowly, such as temperatures, a filter
value of about 1.00 s may be used. The filtering time constant should correspond ap-
proximately to the sensor's time constant.
Parameterising Example:
Number Parameter Value Unit
1514 AnalogIn1_Filter 0,10 s
10.2.3 Error detection in analogue inputs
If a sensor fails (e.g., due to a short circuit or cable break), the control will read all volt-
ages or currents lying outside the normal measuring range. These irregular measuring
values can be used to define inadmissible operating ranges via which the control can
recognize that the sensor is faulty.
For the analogue input, the error limits are entered in the relevant electric unit
The parameter 1512 AnalogIn1_ErrorLow defines the lower error limit.
The parameter 1513 AnalogIn1_ErrorHigh defines the upper error limit.
Parameterising Example:
The manifold pressure sensor connected to the analogue input and operating within a
normal voltage range of 0.5 V to 4.5 V is assumed to supply a voltage of 5 V in case of
cable break and a voltage of 0 V in case of a short circuit. The ranges below 0.3 V and
above 4.7 V are defined as inadmissible by the following parameters:
Number Parameter Value Unit
912 AssignIn_MnfldPress 1
1510 AnalogIn1_RefLow 0.50 V
1511 AnalogIn1_RefHigh 4.50 V
1512 AnalogIn1_ErrorLow 0.30 V
1513 AnalogIn1_ErrorHigh 4.70 V
These error limits chosen should not be too close to the minimum and maximum values,
in order to prevent natural fluctuations of the values measured by the sensors from be-
ing mistaken as errors. On the other hand, it must be ensured that short circuits or cable
breaks are unambiguously recognized as such.
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