B - 7
Appendices B STO Function
High-function General-purpose Inverter RX2 Series User’s Manual
B-2 Procedure for Use of STO Function
B
B-2-2 Retaining Requirements of STO Status
The retention function that retains the blocked status of internal safety path even if STO input is
canceled is not implemented as a safety circuit.
Therefore, if an operation command is input after cancellation of STO input or STO input is canceled
while it is input, the inverter starts output to the motor.
Hence, to satisfy the requirement about cancellation of emergency stop specified in EN/IEC60204-1,
you need to take either of the following measures.
(a) When STO is enabled, this function is used to stop an operation command given to an inverter. It
gives the operation command to the inverter when a user intentionally requires inverter restart.
(b) Design a system in which STO input is reset when a user intentionally requires inverter restart.
Precautions for Correct Use
By setting parameters of the main unit, you can select the following operations.
• Trip the inverter by STO input. In this case, the inverter is tripped and output is stopped until
power is shut off or the error reset signal for the inverter is input.
• If two STO input systems to the inverter are not input at the same time, the inverter is shut off
and enters standby mode until STO input for the two systems is input.
The STO confirmation signal output (EDM output) is the output signal for monitoring the input status of
STO signal and failure detection status on the internal safety path.
Refer to Signal Matrix in the next section when you see output for STO confirmation signal to opera-
tions of ST1/ST2 or error detection status. Turn EDM ON only when both ST1 and ST2 are input cor-
rectly and internal errors are not detected.
B-2-2 Retaining Requirements of STO Status
B-2-3 STO Confirmation Signal Output (EDM Signal)
EDM Output (ED+ / ED-) and Wiring Example
EDM output
Wiring example
Control circuit terminal area
Duty
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