Operating Instructions

Safe Torque Off Function
Test and Fault Confirmation
386 | 443
Troubleshooting Instructions
Use the following instructions for troubleshooting when STO/STL1/STL2/STL3 appear on the keypad (see Fault
Codes for details).
ID No.
KPMS-LE01
Keypad Display
Descriptions
72
STO1–SCM1 internal loop detection error
Cause and Corrective Actions
STO1 and SCM1 short circuit lines are not connected
1. Re-connect the short circuit line.
Hardware failure
1. After you make sure all the wiring is correct, if STL1 fault still exists after cycling the power, return to
the factory for repair.
76
Safe Torque Off function active
Cause and Corrective Actions
The switch action of STO1/SCM1 and STO2/SCM2 (OPEN)
1. Reset the switch (ON) and cycle the power.
77
STO2–SCM2 internal loop detection error.
Cause and Corrective Actions
STO2 and SCM2 short circuit lines are not connected
1. Re-connect the short circuit line.
Hardware failure
1. After you make sure all the wiring is correct, if STL2 fault still exists after cycling the power, return to
the factory for repair.
78
STO1–SCM1 and STO2–SCM2 internal loop detection error.
Cause and Corrective Actions
STO1 and SCM1, or STO2 and SCM2 short circuit lines are not connected
1. Re-connect the short circuit line.
Hardware failure
1. After you make sure all the wiring is correct, if STL3 fault still exists after cycling the power, return to
the factory for repair.
Table 17-5 Instructions for Troubleshooting
Test and Fault Confirmation
After wiring the STO circuit in accordance with Wiring Diagram, follow the steps below to verify that the STO and
related detection functions work normally:
1. When the drive is powered on, ensure that the S1–DCM and S2–DCM voltage falls between 11 and 30 Vdc. At
this time, the drive should enter Standby mode and wait for the RUN command. There is no error displayed on
the keypad.
2. Press RUN on the keypad and use the emergency button or other method to make the S1–DCM and S2–DCM
voltage fall between 0 and 5 Vdc. At the same time, after the output frequency is reached, the drive should
enter Torque Stop mode STO and stop outputting voltage. The keypad displays the STO error, and the
response time of the S1 and S2 signals to cause the drive to stop outputting voltage should be ≤ 20 ms. Then,
restore the S1–DCM and S2–DCM voltage to 11 to 30 Vdc, and press the RESET button on the keypad to clear
the STO error. The drive should enter Standby mode and wait for RUN command.