13. USING STO FUNCTION
13 - 3
13.1.5 Specifications
(1) Specifications
Item Specifications
Functional safety STO (IEC/EN 61800-5-2)
Safety performance
ISO/EN ISO 13849-1 category 3 PL d, IEC 61508 SIL 2,
EN 62061 SIL CL2, EN 61800-5-2 SIL 2
Mean time to dangerous failure
(MTTFd)
100 years or more (Note)
Diagnostic converge (DC) Medium (90% to 99%) (Note)
Average probability of dangerous
failures per hour (PFH) [1/h]
1.68 × 10
-10
Number of on/off times of STO 1,000,000 times
CE marking
LVD: EN 61800-5-1
EMC: EN 61800-3
MD: EN ISO 13849-1, EN 61800-5-2, EN 62061
Note. This is the value required by safety standards.
(2) Function block diagram (STO function)
Base power
supply for
upper arm
Base power
supply for
lower arm
Shut-off signal (STO1)
CN8
Monitor signal (TOFB1)
Shut-off signal (STO2)
Monitor signal (TOFB2)
Shut-
off
Shut-
off
Servo motor
M
Power
module
(3) Operation sequence (STO function)
STO2STO1
ON
OFF
ON
OFF
ON
OFF
ON
OFF
0 r/min
(8 ms)
Servo motor speed
EM2 (Forced stop 2)
Magnetic contactor
Base circuit
(Supplying energy to
the servo motor)
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