PROFIBUS Manual
We can measure the voltage sequence at conductor A:
Idle state: approx. +2 V
Transmitting state:
Minimum voltage approx. +1
Maximum voltage approx. +4 V
Signal on conductor A
The voltage sequence at conductor B is comparable:
Idle state: approx. +3 V
Transmitting state:
Minimum voltage approx. +1V
Maximum voltage approx. +4V
Signal on conductor B
The voltage difference between high and low levels, measured between B and A, should lie between 4 V and 7 V. The values for positive and negative voltage should be roughly equal. The difference between the two values lies in practice around 0.5 V. The idle level should be approx. 1 V.
Differential Signal B-A
The idle state is defined by the active bus termination.
