Operating Instructions

Safe Torque Off Function
Test and Fault Confirmation
387 | 443
3. Press RUN on the keypad and use the emergency button or other method to make the S1–DCM voltage fall
between 0 and 5 Vdc, and the S2–DCM voltage remain between 11 and 30 Vdc after the output frequency is
reached. At this time, the drive should enter Torque Stop mode STL1 and stop outputting voltage. The keypad
displays the STL1 error, and the response time of S1 signals to cause the drive to stop outputting voltage
should be ≤ 20 ms. Then, restore the S1–DCM voltage to 11 to 30 Vdc. However, pressing the RESET button
on the keypad cannot clear the STL1 error. You must cycle the power to the drive. Ensure that the S1–DCM
and S2–DCM voltage falls between 11 and 30 Vdc and cycle the power to the drive, then the STL1 error is
cleared. The drive should enter Standby mode and wait for RUN command.
4. Press RUN on the keypad and use the emergency button or other method to make the S2–DCM voltage fall
between 0 and 5 Vdc, and the S1–DCM voltage remain between 11 and 30 Vdc after the output frequency is
reached. At this time, the drive should enter Torque Stop mode STL2 and stop outputting voltage. The keypad
displays the STL2 error, and the response time of the S2 signals to cause the drive to stop outputting voltage
should be ≤ 20 ms. Then, restore the S2–DCM voltage to 11 to 30 Vdc. However, pressing the RESET button
on the keypad cannot clear the STL2 error. You must cycle the power to the drive. Ensure that the S1–DCM
and S2–DCM voltage falls between 11 and 30 Vdc and cycle the power to the drive, then the STL2 error is
cleared. The drive should enter Standby mode and wait for RUN command.
If you can conduct these four steps normally in sequence with no other error, then the Safe Torque Off function
loop is normal, as shown in the table below. However, if a situation that differs from these four steps, or if STL3
occurs, then the Safe Torque Off function loop does not work normally. See Error Code and Troubleshooting
Instructions for details.
Signal
Status
S1–DCM
ON
ON
OFF
OFF
S2–DCM
ON
OFF
ON
OFF
Drive output
Ready to output
STL2 mode
(Torque output off)
STL1 mode
(Torque output off)
STO mode
(Torque output off)
Error displayed on the
keypad
No error displayed
STL2
STL1
STO
Response time
N/A
≤ 20 ms
RESET mechanism
N/A
Cycle power to the drive
Cycle power to the drive
Press RESET directly
Table 13: Action logic and keypad display description
STO means channel 1 and 2 operate simultaneously and enter Safe Torque Off.
● STL1 means channel 1 operates.
● STL2 means channel 2 operates.
● STL3 means there is an error detected in the internal loop of the channel 1 or channel 2.
● S1–DCM / S2–DCM ON: means S1–DCM / S2–DCM inputs a power supply > 11 Vdc.
● S1–DCM / S2–DCM OFF: means S1–DCM / S2–DCM inputs a power supply < 5 Vdc.