Safe Torque Off Function - Omron R88D-KN01L-ECT-L User Manual

8 Safety Function
8-1

Safe Torque OFF Function

The safe torque OFF function (hereinafter referred to as STO according to IEC 61800-5-2) is used to
cut off the motor current and stop the motor with the input signals from a safety device, such as a safety
controller or safety sensor.
When the STO function is operating, the Servo Drive turns OFF the servo ready completed output
(READY) to go into the safety status.
To connect a Servo Drive to safety device such as a safety controller or a safety sensor, use the safety
connector (CN8).
The PFH value is 2.30 × 10
Precautions for Safe Use
• When using the STO function, be sure to execute a risk assessment of the equipment to
confirm that the system safety requirements are met.
• There are the following risks even when the STO function is operating. Be sure to take safety
into account as part of the risk assessment.
• The motor runs if an external force is present. If holding is required, implement appropriate
measures, such as providing external brakes.
• Even if there is no external force, when the Fault reaction option code (605E hex) is set to
free-run with the dynamic brake disabled, the motor uses free-run stopping and the stop
distance is long.
• In case of internal failure of components, the motor may operate in the range of up to 180
degrees of electrical angle.
• The power supply to the motor is cut off by the STO function, but the power supply to the
Servo Drive will not be cut off nor electrically isolated. For Servo Drive maintenance, cut off
the power supply to the Servo Drive through another means.
• The EDM output signal is not a safety output. Do not use the EDM output for any purpose
other than the failure monitoring function.
• Be sure to perform wiring checks during installation. In particular, check for the following
points.
• There are no shorted or disconnected wires.
• The polarity of the EDM circuit is not reversed.
• The SF1, SF2, and EDM signals turn ON/OFF correctly.
• The Servo Drive's safety function could be impaired if it is wired incorrectly.
• The dynamic brake and external brake release signal outputs are not safety-related parts.
Make sure to design the equipment not to be dangerous even if the external brake release fails
during the STO status.
• When using the STO function, connect equipment that meets the safety standards.
Precautions for Correct Use Precautions for Correct Use
According to EN61800-5-2, the safety function is referred to as the "Safe torque off" function
using the word "torque" instead of force. Read it as "force" when using this function.
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G5-series Linear Motors/Servo Drives With Built-in EtherCAT Communications