Symbol SE955 Integration Manual page 225

TXD
(Host RXD)
RXD
(Host TXD)
RTS
(Host CTS)
2
CTS
(Host RTS)
1
1. Host requests permission to send
2. Decoder grants permission
3. Host sends 3 nulls, then BEEP command
4. Host removes request when finished sending
5. Decoder removes permission
6. Decoder ACKs
Figure A-5. Host Initiated Transmission with Leading Nulls
(Decoder in Continuous Power Mode)
6
3
4
Serial Interface Specification A-9
5