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Invalid Dominant Level
Invalid Recessive Level
Invalid Termination
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Invalid dominant levels can be caused by
• too high cable resistances
• too many or faulty terminating resistors
• output resistors in the driver stages
• fault currents
Invalid recessive levels can be caused by
• missing terminating resistors
• fault currents
Under certain conditions a faulty bus termination can be detected by a
measurement of the DC resistance. A distinction must be made between
the following cases:
• There are no terminating resistors at all
• Only one terminating bus resistor is connected
• More than two terminating bus resistors are connected
A reliable statement on the correct termination cannot be made by means
of a DC measurement. It is for example not possible to detect whether
both resistors are connected at one cable end.
Further termination errors can be caused by the topology of the network.
A more reliable statement on the correct termination must take the high-
frequency behaviour into account. This is possible with the evaluation of
the signal shape by means of the indications Slow Slopes and Over-
/Undershoots.
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