Attention !
Switch 4 must not be activated if a Profibus system consisting of 2 or more nodes
is installed on the other side of the data transmission units. Bus communication
between the nodes would otherwise suffer interference.
Functionality of switch 4
0
The data lines are switched to high impedance (Tristate) when visual contact
is lost. Tristate is the standard application case.
The system behaves as it would in the event of a line interruption.
1
If the transmission path is interrupted, bus occupation is simulated until visual
contact is re-established. Normal exchange of data then resumes. In this way,
token regeneration on one of the interrupted nodes is prevented.
Advantages
·
Shorter bus access times for Profibus systems in Multi-Master configuration
once visual contact has been re-established.
For example, when moving high-bay storage and retrieval units from one aisle to
another, the interruption routine is carried out faster, thereby reducing the time
required to make the entire system available after activating the switch.
Fig. 15: Selector switch during loss of visual contact
Leuze electronic
DDLS 170
19
