Operating Instructions
IS1 PROFIBUS 3.00 E
- Technical alterations reserved -
28
PROFIBUS DP interface for IS1+
CPU redundancy according Stahl specification
2.10.2.1
Functions
An IS1+ field station can be equipped with two central units (CPU), whereby each CPU has its own independent
PROFIBUS DP interface.
From the point of view of the automation system, each field station has 2 separate DP slaves, and both are
involved in the cyclical data exchange with the DP master. Thus, there are two independent transmission paths
between the DP master and the field station.
These two transmission paths are monitored for proper and error-free operation by
user software in the
automation system
. In addition, one of the transmission paths is selected to transmit the useful data. The
CPU linked to the transmission path selected by the AS is switched to primary mode (active) by transmitting a
control register from the AS to the CPU.
Of course, data can also be transmitted through the other (inactive) transmission path. However, it only helps
to monitor the connection. Data transmitted here is not used.
Only the active CPU handles the data traffic to the field station I/O modules. The active CPU monitors the
inactive CPU and likewise provides it with the current input data.
2.10.2.2
Redundancy structures
The following redundant PROFIBUS network structures are supported:
Cable redundancy in the Ex Area
Redundant transmission units (CPU) in the IS1+ field station,
Non-redundant DP master.
IS1+ Fieldstation
CPU
left
CPU
right
I/O
Module
Non Ex Area
Ex Area
AS
DP
Master
Module
9185
PROFIBUS DP
