Propagation delay and reaction time of the Interbus

The transmission of the signals from the input into the controller and from the controller to the outputs is subject to a propagation delay. It is composed of a number of elements: Transmission from the controller into the master; transmission via the Interbus and transmission from the Bus Coupler to the outputs, this applies in the reverse order to the return path. Please refer to the master manufacturer's data for the reaction time from the controller to the master. The newly transmitted data only become valid after the complete transmission of a cycle. The reaction time TIBS on the INTERBUS is composed as follows. The constants SW, M, N and TBIT form the sum for the cycle time in milliseconds. The reaction in the worst case is 2 x cycle time, as the data only become valid after the end of the cycle.

TIBS = ( SW + (13 x ( 6 + N ) + 1.5 x M ) x TBIT ) x 2
SW = 0.2 ms
M = number of Bus Couplers
N = number of the effective byte lengths
TBIT = 0.002 ms
Observe the number of bytes and not the word length when calculating the times.

Delays in the case of transmission errors Observe special delays in the case of transmission errors. The Interbus requires 5 cycle times before the next valid data can be exchanged.