Chapter 14 Safety Function STO
14-1-3
14.1.2 STO State Monitor Output (EDM Signal)
ï‚Ÿ How to check the operation of STO function by enabling STO state monitor output (EDM
signal)?
ï‚Ÿ When using STO state monitor output (EDM signal), turn ON EDM switch on the control circuit
terminal. "Output terminal [11] function [C021]" is automatically changed to "STO state monitor
output [EDM] (62)". At the same time, "Output terminal [11] active state [C031]" becomes "NO:
Normally Open (00)".
ï‚Ÿ STO state monitor output (EDM signal) is a reference signal for monitoring the input status of
STO signal and failure detection status of the internal safety path. It is not permitted to activate
the safety function using this signal.
ï‚Ÿ Refer to the signal matrix in the table below for the
ï‚Ÿ operation of EDM signal for [ST1]/[ST2] and failure detection status. EDM signal turns ON only
when both STO inputs are correctly input and internal failure is not detected.
*1. Correspondence between the input status of [ST1]/[ST2] and
the contact status: Operation permitted = contact ON, STO = contact OFF
ï‚Ÿ When the EDM switch is ON, input terminals 3 and 4 of "Input terminal monitor [d005]" indicate
the status of [ST1]/[ST2], respectively. For details, see section "10.2.1 Monitor the Status of
Input and Output Terminals".
ï‚Ÿ When EDM switch is turned OFF from ON, "Output terminal [11] function [C021]" is
automatically changed to "No assignment (no)".
â– STO timing chart
ï‚Ÿ The timing chart of the output to the motor and EDM signal for STO input [ST1]/[ST2] is shown
below. The output to the motor is shut off within 20 ms after [ST1] and [ST2] are turned off.
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