System modifications during redundant operation   
10.1 System modifications during operation 
  CPU 410-5H Process Automation/CPU 410 SMART 
136  System Manual, 10/2013, A5E32631667-AA 
What should I consider during system planning? 
For switched I/O to be expanded during operation, the following points must be taken into 
account already at the system planning stage: 
●  In both cables of a redundant DP master system, sufficient numbers of branching points 
are to be provided for spur lines or isolating points (spur lines are not permitted for 
transmission rates of 12 Mbit/s). These branching points can be spaced or implemented 
at any points that can be accessed easily. 
●  Both cables must be uniquely identified so that the line which is currently active is not 
accidentally cut off. This identification should be visible not only at the end points of a 
line, but also at each possible new connection point. Different colored cables are 
especially suitable for this. 
●  Modular DP slave stations (ET 200M), DP/PA links and Y links must always be installed 
with an active backplane bus and fitted with all the bus modules required wherever 
possible, because the bus modules cannot be installed and removed during operation. 
●  The removal of the terminal modules with the ET200iSP should have sufficient reserves 
and be fitted with unconfigured reserve modules. 
●  Always terminate both ends of PROFIBUS DP and PROFIBUS PA bus cables using 
active bus terminating elements in order to ensure proper termination of the cables while 
you are reconfiguring the system. 
●  PROFIBUS PA bus systems should be built up using components from the SpliTConnect 
product range (see interactive catalog CA01) so that separation of the lines is not 
required. 
Modification of the hardware configuration 
With a few exceptions, all elements of the configuration can be modified during operation. 
Usually configuration changes will also affect the user program. 
The following must not be changed by means of system modifications during operation: 
●  Certain CPU parameters (for details refer to the relevant sections) 
●  PN configurations 
●  The transmission rate (baud rate) of redundant DP master systems 
●  S7 and S7 H connections 
Modifications to the user program and the connection configuration 
The modifications to the user program and connection configuration are loaded into the 
target system in redundant system state. More detailed information can be found in Manuals 
PCS 7, Configuration Manual
.