Mitsubishi Electric MELSEC iQ-R User Manual page 253

Who-Is send request (Y6)
Turn Y6 OFF and ON, and OFF again when broadcasting Who-Is services.
'Who-Is send complete' (X6) is the interlock condition of Y6. Y6 turns OFF by turning X6 OFF and ON, and OFF again.
The timing to change the device status is as follows.
ON
Y6
ON
(1)
X6
(1) Sending status of a Who-Is service
OFF
OFF
ON
OFF
APPX
251
Appendix 1 I/O Signals
A