Tag
Tag initiate sending data
BU
500
Data
Ack
Tag
BU initiate sending messages
BU
500
Ack
Message
1
Data
Ack
20 minutes
Message
1
retry
*
Message
2
Ack
Tag
IDU
Data
ID Req
Optic
RF
Legend:
Only IDU can initiate ID request
*When no ACK from tag
No retries when tag sends data
