Hi,
While going through a controller manual i encountered this in the failure detection of analog inputs portion of the manual:
The fundamental principle of error detection with analog or digital inputs is
redundancy, i.e. two voltages with opposite characteristic curves with a defined
reference to each other are used for an input function and mutual plausibility is
checked.
In the event of a short circuit between the two mutually referenced signals,
the resulting voltage must either be outside the expected mutual reference
or it must be defined as a safe state (neutral).
Beyond this principle of redundancy the ranges of the signal can be monitored by the
control unit software. That is possible if the voltages in error-free operation do not
exceed the overall range of the input channel voltage so that failures such as cable
breaks or short circuits to a sensor supply would result in an impermissible voltage,
which can then be discovered.
I am familiar with CRC used in communication protocols but i could not understand what this meant. Can someone explain this , especially the part "two voltages with opposite characterstic curves with a defined reference". How this would translate to a real scenario, for ex. say if i am reading a potentiometer value on an analog pin.
While going through a controller manual i encountered this in the failure detection of analog inputs portion of the manual:
The fundamental principle of error detection with analog or digital inputs is
redundancy, i.e. two voltages with opposite characteristic curves with a defined
reference to each other are used for an input function and mutual plausibility is
checked.
In the event of a short circuit between the two mutually referenced signals,
the resulting voltage must either be outside the expected mutual reference
or it must be defined as a safe state (neutral).
Beyond this principle of redundancy the ranges of the signal can be monitored by the
control unit software. That is possible if the voltages in error-free operation do not
exceed the overall range of the input channel voltage so that failures such as cable
breaks or short circuits to a sensor supply would result in an impermissible voltage,
which can then be discovered.
I am familiar with CRC used in communication protocols but i could not understand what this meant. Can someone explain this , especially the part "two voltages with opposite characterstic curves with a defined reference". How this would translate to a real scenario, for ex. say if i am reading a potentiometer value on an analog pin.