Mitsubishi Electric MELSEC iQ-R Series Safety Manual page 31

■Using a Safety CPU and two safety remote I/O modules (connecting the extension module to
only one module)
Connect the emergency stop switch to the main module of the safety remote I/O module. Connect the safety relay to another
extension module of the safety remote I/O module. Safety CPU controls on/off of the safety relay according to the input from
the emergency stop switch.
• PFDavg/PFH of A: PFDavg/PFH value of a Safety CPU (paired with the safety function module) on the safety path
• PFDavg/PFH of B: PFDavg/PFH value of main module B, since only used for main module
• PFDavg/PFH of C: PFDavg/PFH value when connecting extension module (C2) to the main module (C1)
• PFDavg/PFH of D: PFDavg/PFH value of the emergency stop switch
• PFDavg/PFH of E: PFDavg/PFH value of the safety relay
PFDavg = (PFDavg of A) + (PFDavg of B) + (PFDavg of C1 and C2) + (PFDavg of D) + (PFDavg of E)
-5 -5
= (1.02  10 ) + (3.54  10
-5
= (9.22  10
) + (PFDavg of D) + (PFDavg of E)
PFH = (PFH of A) + (PFH of B) + (PFH of C1 and C2) + (PFH of D) + (PFH of E)
-9 -9
= (5.50  10 ) + (3.55  10
-8
= (1.38  10
) + (PFH of D) + (PFH of E)
A
B
Input
D
Emergency
stop switch
-5
) + (4.66  10
) + (PFDavg of D) + (PFDavg of E)
-9
) + (4.78  10
) + (PFH of D) + (PFH of E)
C1
Output
Safety
relay
4 PRECAUTIONS FOR USE OF SAFETY PROGRAMMABLE CONTROLLER
C2
E
4.1 Precautions for Designing Safety Application
4
29