Figure 44: Profisafe Layer Model - WAGO 750 Manual

114 Appendix

Figure 44: PROFIsafe Layer Model

The PROFIsafe telegrams are transferred between the safe PLC and the F I/O
module via the so-called "black channel." The "black channel" extends from the
PROFINET connection of the PLC, to the fieldbus coupler/controller, the local
bus in the node, to the F I/O module. The PROFIsafe telegrams are only
evaluated in the safe PLC and in the F I/O module.
If communication errors are detected, the F I/O modules are passivated by all
safe outputs being switched off and the safe substitute values being transferred
to the safe PLC as an input process image.
The evaluation of the input process image and the output of the output process
image via the F I/O module with digital outputs are performed by the safe PLC.
Note the following guidelines and information when setting up PROFIsafe
applications:
• PROFIsafe Guidelines – Requirements for Installation, Immunity and
Electrical Safety (PROFsafe Environmental Requirements, current version)
• Installation recommendations (PROFIBUS Installation Guidelines, current
version)
These documents are available on the Internet at http://www.profibus.com/.
Manual
Version 1.0.0, valid from HW/SW Version 01/01
WAGO I/O System 750
753-661/000-004 4FDI 24V PROFIsafe