94
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. The scanner starts to send data
2. The host interrupts the scanner sending data and sends PARAM_REQUEST command
3. The scanner sends PARAM_SEND data packet to reply host’s PARAM_REQUEST command
4. The scanner resends the interrupting data（all data is resent）
6. The host sends ACK
Figure 4-3 Timing control
