Siemens SINUMERIK 840D sl Function Manual page 37

Figure 3-3
Features of the two-channel, diverse structure
A two-channel, diverse structure is characterized by the following features:
● Two-channel structure with at least 2 independent computers (i.e. computers with different
hardware and software).
● Crosswise result and data comparison with forced checking procedure for the purpose of
detecting internal errors even in functions that are not often used (dormant errors).
Detecting
In order to connect sensors and actuators in a safety-related fashion, their process signals
must be connected for further processing.
Evaluating
The two drive CPUs independently execute the safety-related functions. The CPUs cyclically
and mutually compare their safety-related data and results (crosswise data comparison). A
test can be carried out - initiated by the CPUs - to check the switch-off signal paths and
actuators (forced checking procedure).
Safety Integrated
Function Manual, 12/2017, 6FC5397-4BP40-6BA1
Safety functions integrated in the drive in conjunction with SINUMERIK
3.3 Safety technology integrated in the drive
Brief description
37