Unitech ES910, Руководство пользователя

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4-16 The control of timing conflict
If the scanner has started the data transmission, while the host sends commands to the scanner, once
the scanner receives complete command, it stops its data transmission to respond the host command,
and then restart the terminated data transmission, due to the data transmitted in packet format, the host
can accurately separate from the received data: 1) response information. 2) information about
transmitted data originally.
RXD
(Host TXD)
TXD
(Host RXD)
1
3
5 2
4
1. T he scanner starts to send data
2. T he host interrupts the scanner sending data and sends P A R A M _R E Q U E S T com m and
3. T he scanner sends P A R A M _S E N D data packet to reply host’
s P A R A M _R E Q U E S T com m and
4. T he scanner resends the interrupting data （ all data is resent ）
6. T he host sends A C K
Figure 4-3 Timing control