Relationship between Master and Slaves during Safety Process Da-
ta Communications
The following figure shows the safety master/slave relationship during safety process data communi-
cations.
NX-series CPU
Unit
Coupler
Unit
Coupler
Unit
1S-series Servo
Driver
Safety Input
Safety Input
Safety Output
Safety Output
Safety Input
Safety Output
Safety
CPU Unit
Safety process data communications
Safety master
Safety slave
EtherCAT
NJ/NX-series
CPU Unit
Coupler
Unit
Coupler
Unit
1S-series Servo
Driver
Safety Input
Safety Output
Safety Input
Safety Output
Safety
CPU Unit
Safety process data communications
Safety master
Safety slave
EtherCAT
S SS
S S S S
S
M
M
S SS
S
S S
M
M
The Safety CPU Unit performs safety process data communications with the following devices using
the FSoE protocol.
• Safety I/O Unit on the same CPU rack or the same Slave T
erminal
• Safety I/O Unit on the Slave Terminal on the EtherCAT network
• EtherCAT slave with the FSoE slave function on the EtherCAT network (OMRON 1S-series Servo
Driver)
In the example above, the Safety CPU Unit operates as a master of safety process data communica-
tions. The 1S-series Servo Driver or the Safety I/O Unit operates as a slave of safety process data
communications.
The NJ/NX-series CPU Unit and the Communications Coupler Unit relay safety process data commu-
nications between a safety master unit and a safety slave unit.
Relationship between Master and Slaves during Standard Process
Data Communications
The Safety Control Unit operates as a standard slave of a standard CPU Unit through the connected
NX bus master. Safety process data communications with the standard CPU Unit are not available.
4 Safety Control Unit Operation
4 - 3
NX-series Safety Control Unit User's Manual (Z930)
4-1 Relationship between Units and Types of Communications
4
4-1-1 Safety Control System on CPU Rack or EtherCAT Network