ABB FSO-21 - PROFIsafe

Technical data 521
• Speed measurement subsystem is a mix of two different safety data as the
speed estimation is calculated independently by the FSO and the drive. In the
safety data tables, these two safety data are already combined in the safety data
of this subsystem. This subsystem can be used together with the following safety
functions: STO (with or without SBC), SS1, SSE, SLS, varSLS, SMS, and SSM.
Note: POUS does not use any speed measurement subsystem.
• PROFIsafe is a subsystem for the reliability of PROFIsafe connection. This
subsystem is used in case the PROFIsafe connection is in use in the application
through FENA-21 or FPNO-21 module. FSO module takes care of the reliability
and safety of this connection.
• Logic subsystem is included in each safety function implemented with the FSO.
Logic subsystem is divided into Logic 1 and Logic 2. If the safety function contains
any single channel digital input or output without diagnostic pulses, the subsystem
"Logic 1" must be used. Otherwise the subsystem "Logic 2" is used.
• STO output from the FSO to the Drive STO. STO is a critical subsystem for all
safety functions other than SSM. Therefore it shall be included in safety
calculations of those functions.
• Drive STO is the actuator for the STO of the drive. For the safety data, see the
drive hardware manual.
Note: All safety functions (except SSM) have the capability to activate STO. This
means that STO subsystems (STO output and Drive STO) are always part of the
safety function's calculations even though it might not be activated in normal use.
• Speed measurement with FSE-31 is a subsystem for safety encoder interface,
FSE-31. This subsystem can be used with following safety functions: STO (with or
without SBC), SS1, SSE, SLS, varSLS, SMS, SSM, and SDI. SDI and STO with
speed limit activated SBC always use speed measurement with encoder.
• Sensors, input devices, encoders, PLCs, and possible additional actuators.
See section FSO safety calculations guide (without PROFIsafe) on page 524. For
the safety data, see the manufacturer's documentation.
Safety data for some typical configurations of these subsystems is precalculated and
shown in section Safety data for some typical configurations on page 529.
After calculating the total PFDavg/PFH for the safety function, it must be verified that
the PFDavg/PFH of the safety function fulfills the requirement for the targeted SIL/PL.
For additional information on safety calculations, see standards EN ISO 13849-1,
EN/IEC 62061, IEC 61508, IEC 61511, or ABB Drives Technical guide No. 10,
Functional safety (3AUA0000048753 [English]).