Sto Status Retention Function; Sto Confirmation Signal Output (Edm Signal) - Hitachi SJ Series User Manual

Chapter 21
21.4.4

STO Status Retention Function

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.
(1) At the same time as STO input, set the operation
command to the inverter to stopped status
(2) Configure the system so that STO input to SJ-P1 is
canceled when system reboot is required by the user.
By setting parameters of the main unit, you can select the
following operations. (see 4.7)
(1) 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.
(2) 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.
21.4.5 STO Confirmation Signal Output (EDM
Signal)
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.
EDM terminal (ED+ / ED-) and wiring example
Control circuit terminal area
STO
confirmation
terminal
For operation of ST1/St2 and output of STO confirmation
signal against failure detection status, see the matrix
below. EDM turns ON only when both STO inputs are
correctly input and internal failure is not detected.
Signal matrix
Signal Status 1
ST1 *1) STO
ST2 *1) STO
Failure None
detection
EDM ON
Output to Off
the motor
*1) The following table shows the correspondence
between the input status of ST1/ST2 described
in the table above and status of contact points.
Input status
STO
Operation permitted
21-38
Technical Notes
ED+ ED-
Duty
Wiring example
Status 2 Status 3 Status 4
Operation STO Operation
permitted permitted
STO Operation Operation
permitted permitted
None None None
OFF OFF OFF
Off Off Output
permitted
Contact point
OFF
ON
Status 5
*
*
Detected
OFF
Off