Run Operating State; Table 8-2 Causes Of Error Leading To Redundancy Loss - Siemens SIMATIC S7-400H System Manual

System and operating states of the S7-400H
8.4 The operating states of the CPUs
8.4.4

RUN operating state

Except for the additions described below, the behavior of S7-400H CPUs in RUN corresponds
to that of standard S7-400 CPUs.
The user program is executed by at least one of the two CPUs in the following system states:
● Single mode
● Link-up, Update
● Redundant
Single mode, Link-up, Update
In the system states mentioned above, the master CPU is in RUN and executes the user
program in single mode.
Redundant mode
The master and standby CPUs are always in RUN when operating in redundant state,
execute the user program in synchronism, and perform mutual checks.
In the redundant state it is not possible to test the user program with breakpoints.
The redundant state is only supported with CPUs of the same version and firmware version.
Redundancy will be lost if one of the errors listed in the following table occurs.
Table 8-2
Cause of error
Failure of one CPU
Failure of the redundant link (synchronization
module or fiber-optic cable)
RAM comparison error
Redundant use of modules
The following rule applies to the redundant state:
Modules interconnected in redundant mode, such as DP slave interface module IM 153-2,
must be in identical pairs, i.e. the two redundant linked modules have the same order
number, release and firmware version.
86
Causes of error leading to redundancy loss
Reaction
Failure and replacement of a CPU (Page 186)
Failure and replacement of a synchronization
module or fiber-optic cable (Page 192)
TROUBLESHOOTING operating state (Page 87)
System Manual, 09/2007, A5E00267695-03
S7-400H