R.T.A. s.r.l. – XPETME05 – 11/20
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12.8-
ENABLE / DISABLE STO: TIMING INDICATIONS
The correct and stable enabling of STO function is effective after a maximum time of 20 ms after
STO1 and STO2 switching off.
Monitor Output indicates that STO function is active with a maximum delay of 20 ms from STO1 and
STO2 input signals switch off (Figure 18).
ON 24 V
max 20ms
OFF 0 V
DRIVE
STATE
MONITOR
STATE
STO1, STO2
ON
SAFE TORQUE OFF
Fig. 18 – STO Timing.
12.9-
TIMING OF INPUT-OFF SHOT PULSE FOR SAFETY DEVICE SELF-DIAGNOSIS
In case of the safety device perform self-diagnosis through input-off shot pulses, the input-off shot
pulse must have a maximum duration of 1 ms.
STO function is not activated when the period of STO inputs signal STO1 / STO2 - OFF is 1 ms or
less.
In order to surely grant the activation of the Safe Torque Off function, it is necessary that STO1 and
STO2 input signals are turned off for 20 ms or more (Figure 19).
Note:
When STO1 and STO2 input signals switch ON and OFF in a range of 1-20 ms, motor loss of
synchronism and/or wrong signaling can occour.
ON
max 1ms
OFF
DRIVE
STATE
MONITOR
STATE
STO1, STO2
ON
SAFE TORQUE
OFF
max 20ms
Fig. 19 –STO Self-Diagnosis Timing.
