ABB FSO-21, User Manual

Page: 62 / 540

62 Safety functions
At power-up, the FSO goes into the Start-up mode. During the power-up process,
FSO is in Safe state (STO active). It performs start-up checks and, according to the
configuration, enters the Operational state either automatically or after an
acknowledgement request from the FSO I/O or from a safety PLC.
The Drive composer pro PC tool can request the Configuration mode, when the FSO
is in the Start-up, Operational, Safe or Fail-safe mode and the drive is in the Torque
off mode (not modulating). The FSO exits the Configuration mode into the Start-up
mode when the user either:
• downloads the new configuration to the FSO, or
• reboots the module
(for rebooting instructions, see chapter FSO recovery on page
504 ).
If there is an internal fault, the FSO enters the Fail-safe mode. To identify and recover
from the cause of the fault, see section
FSO recovery on page 504 .
The FSO exits the Fail-safe mode into the Start-up mode when the user reboots the
module (for rebooting instructions, see chapter
FSO recovery on page 504 ).
When the FSO is in the Power down, Start-up, Configuration, Safe or Fail-safe mode,
the drive STO function is always active. When the FSO is in the Operational state, the
drive STO function is inactive (except when the POUS function is active, the drive
STO function is also active).
Note : When the drive is connected to a safety PLC via the PROFIsafe over
PROFINET communication bus, see the states diagrams in section FSO module
modes and states on page 212 in chapter PROFIsafe .

Cascade
It is possible to cascade up to six FSO modules into a daisy-chain type network
(resembles somewhat an I/O master/follower system): If an FSO triggers a cascaded
safety function, it passes the triggering information to the next FSO, which triggers
the next one, and so on, until the last FSO again triggers the first one.
Without a PROFIsafe communication bus, you can cascade only safety functions
which have a primary and a secondary digital input: STO, SS1, SSE,SLS1, SDI
positive and SDI negative.
If you want to a cascade safety function which has only one digital input (SLS2,
SLS3, SLS4, SSM1, SSM2, SSM3, SSM4), you must have a PROFIsafe
communication bus and configure the safety function request from a safety PLC.
For detailed configuration instructions, see section How to configure a cascaded
system on page 322 .
This figure shows an example cascade configuration. Two different safety functions
are cascaded in the same cascaded system. Safety function 1 is cascaded in one
cascade loop (Cascade A) and safety function 2 in another (Cascade B).